Table of Contents
Page
Section 1
Introduction and General Planning Requirements
Purpose of This Volume Who Should Use This Volume Related Reference Material General Planning and Design Approval Requirements Guidelines for Design Calculations Guidelines for Drawings
3 3 3 4 5 7
Table 1.1
Recommended Population Equivalent
6
Figure 1.2 Typical Process and Installation Diagram
10
Figure 1.4 Typical Mass Balance Diagram
12
1.1 1.2 1.3 1.4 1.5 1.6
Figure 1.1 Typical Hydraulic Profile
Figure 1.3 Typical Process Flow Diagram
Figure 1.5 Typical Electrical Single Line Diagram Section 2
2.1
Design Overview
2.2
2.3
11
12
Treatment Plant Classification
15
2.1.2 Classification by Treatment Plant Capacity
16
2.2.1 General Selection Considerations
16
2.1.1 Classification by Biological Treatment Processes
9
Treatment System Selection / Design 2.2.2 Design Stages
2.2.3 Detailed Design Criteria Safety and Health Principles 2.3.1 General Safety
2.3.2 Structural Safety
2.3.3 Equipment and Electrical Safety
15
16 20 20
23
23 24
25
Table 2.1
Classification by Treatment Plant Capacity
Section 3
Sewage Characteristics and Effluent Discharge Requirements
3.1
3.2
16
Introduction
29
3.2.1 Purpose of Effluent Standards
29
EQA Effluent Standards
3.2.2 Interpretation of EQA Effluent Standards
29 29
i
3.3
3.4
Design Requirements to Achieve EQA Effluent Standards
30
3.3.2 Design Values
30
3.3.1 Purpose of Design Requirements Sewage Pollutants Removal
31
3.4.3 Chemical Oxygen Demand (COD)
32
3.4.2 Total Suspended Solid (TSS)
3.4.4 Oil and Grease (O&G)
3.5
3.4.5 Nitrogenous Compound 3.4.6 Phosphorus Compound
Sludge Characteristics and Treatment Requirements
Table 3.1
Design Influent Values
Section 4
Requirements for Physical Design
Table 3.2
4.1
4.2
4.3
4.4
ii
31
3.4.1 Biochemical Oxygen Demand (BOD5)
30
Design Effluent Values
32
32
33
33
34 30
31
Introduction
37
4.2.1 Buffer Zones
37
Treatment Plant Siting 4.2.2 Siting Criteria
4.2.3 Environmental Impact Assessment 4.2.4 Hazard and Operability Studies Treatment Plant Sizing 4.3.1 Modular Units 4.3.2 Standby Units
4.3.3 Back-up Capacity 4.3.4 Design Flow
Land Area Requirements
4.4.1 Class 1 and 2 Plants
4.4.2 Mechanised Class 3 to 4 Plants
4.4.3 Aerated Lagoons and Stabilisation Ponds 4.4.4 Imperfect Sites
4.4.5 Reduced Land Areas for STPs
37
39
39
40
40
40
40
41
42
42
42
42
43
43
43
4.5
Mechanical and Electrical Requirements
53
4.5.2 Vibration
54
4.5.1 Mechanical Installation
4.5.3 Noise
4.5.4 Safety Around Equipment
4.5.5 Motors, Controllers and Motor Starters 4.5.6 Power Supply Systems 4.5.7 Back-up Generator
4.5.8 Switchgear and Control Gear Assemblies 4.5.9 Control Cabinets
4.5.10 Control Requirements
4.5.11 Supervisory Control and Data Acquisition
Systems (SCADA)
53 54 55
55
57 58
59 60 62
64
4.5.12 Early Warning System (EWS)
65
4.5.14 Cables and Cabling Installation
67
4.6
Table 4.1
Table 4.3
Table 4.2
Table 4.4
Table 4.5
Table 4.6
4.5.13 Instrumentation
4.5.15 Earthing and Lightning Protection 4.5.16 General Purpose Power
4.5.17 Manuals, Drawings and Labelling 4.5.18 Hazardous Areas
Material Requirements for STP Structures and Installations 4.6.1 Concrete and Reinforcement 4.6.2 Steel
4.6.3 Fibre Reinforced Plastic (FRP) 4.6.4 Aluminium
4.6.5 HDPE (High Density Polyethylene) Modulation Requirements
Land Area Requirements for Class 1 Land Area Requirement for Class 2 Land Area Requirements for
Land Area Requirements for
Required Land Area for Stabilisation Pond and Aerated Lagoons
65
68
69 69 70
70 70
72
74 76
77 40 44
45 45
46
47
iii
Figure 4.1
STP Land Area Requirements for Planning Layout Approval 49 for New Development
Guidelines For Buffer Zone
Figure 4.2
Figure 4.4
Figure 4.3
Figure 4.5 Section 5
5.1
5.2
5.3
5.4
5.5
5.6 5.7 5.8
iv
STP Land Area Requirements for Structure Plans
50
Plan View of Buffer Zone Requirements
52
Clear Working Space
Requirements for Individual Treatment Processes
51
57
Introduction
81
5.2.1 Purpose of Primary Screens
84
Design of Primary Screens 5.2.2 Inlet Chamber
5.2.3 Design Requirements for Primary Screens 5.2.4 General Requirements Design of Pump Stations
5.3.1 Purpose of Pump Stations 5.3.2 Design Requirements
5.3.3 General Requirements
84
84
85
86
91
91
91
95
Design of Secondary Screens
100
5.4.2 Design Requirements
100
5.4.1 Purpose of Secondary Screens Design of Grit and Grease Chambers
5.5.1 Purposes of Grit and Grease Chambers 5.5.2 General Requirements 5.5.3 Design Criteria Design of Balancing Tanks 5.6.1 Purposes of Balancing Tanks 5.6.2 Design Requirements Design of Primary Sedimentation Stage 5.7.1 Purposes 5.7.2 Design Requirements Design of Biological Treatment Stage 5.8.1 Introduction 5.8.2 Conventional Activated Sludge System (CAS) 5.8.3 Extended Aeration System (EA) 5.8.4 Rotating Biological Contactors (RBC) 5.8.5 Trickling Filter
100
101
101 102 103 105 105 105 106 106 106 108 108 109 111 114 116
5.8.6 Sequencing Batch Reactors (SBR) System 117 5.8.7 Design Requirements for Hybrid Systems 120 5.8.8 Design for Nutrient Removal for Sensitive 120 Receiving Water 5.9 Design of Secondary Clarifiers 122 5.9.1 Purpose 122 5.9.2 Design Requirements 122 5.9.3 Multiple Hoppers 123 5.10 Disinfection 125 5.10.1 Design Requirements 126 5.11 Design of Flow Measurement Devices 130 5.11.1 Purpose of Flow Measuring Devices 135 5.11.2 Design Requirements for Flow Devices 135 5.12 Sludge Holding, Treatment and Disposal 136 5.12.1 Introduction 136 5.12.2 Sludge Strategy in General 137 5.12.3 Provision of Sludge Holding, Treatment and Disposal 138 5.12.4 Design Criteria 139 5.13 Tertiary Treatment 144 5.13.1 Introduction 144 5.13.2 Design Requirement 144 Table 5.1 Table 5.2 Table 5.3 Table 5.4 Table 5.5 Table 5.6 Table 5.7 Table 5.8 Table 5.9 Table 5.10 Table 5.11 Table 5.12 Table 5.13 Table 5.14
Requirement for Inlet Chamber Provision of Primary Screens Design Parameters for Primary Screens Recommended Design Parameters for Inlet Pump Stations Provision Requirement of Secondary Screens Design Parameters for Secondary Screens Provision Requirement of Grit and Grease Removal System Design Parameters for Grit Chambers Design Parameters for Grease Chambers Design Parameters for Balancing Tanks Design Parameters for Primary Sedimentation Design Parameters for Conventional Activated Sludge System Design Parameters for Extended Aeration Design Parameters for RBC Plants
84 85 86 99 100 101 103 103 104 106 108 110 111 112 v
Table 5.15
Table 5.16
Table 5.17
Table 5.18
Table 5.20
Table 5.19
Table 5.21
Table 5.22
Table 5.23
Table 5.24
Table 5.25
Table 5.26
Table 5.27 Figure 5.1
Figure 5.2 Figure 5.3
Figure 5.4 Figure 5.5
Figure 5.6
Figure 5.7
Figure 5.9
Figure 5.8
Design Parameters for Trickling Filter
117
Design Requirement for Biological Nutrient Removal System
120
Requirements for Disinfection Facility
126
Design Requirements for SBR System
Design Parameters for Secondary Clarifiers
124
Design Guides for Disinfection with Ultra-Violet (UV)
130
Design Guide for Disinfection with Hypochlorite Design Guide for Intermittent Disinfection Design Parameters for Flow Devices Sludge Generation Rates
Design Parameters for Sludge Thickening
Design Parameters for Aerobic and Anaerobic Digestion Recommended Design Parameters for Sludge Treatment Typical Treatment Process Flow Chart
Typical Elements and Process Flow Diagram of a Sewage Treatment Plant Typical Drawing of Double Penstock
Quantities of Screenings Collected From Primary Screens Typical drawing of screen chamber based on depth. (<5m for different PE)
133
134
135
136
139
140
141
82 83
85
88 89
Typical drawing of screen chamber based on depth. (<5m for different PE)
90
Typical Dimensions of Dry-well Submersible Pump Station
94
Typical Dimensions of Wet-well Submersible Pump Station
93
Typical details of wet-well pump station
97
Figure 5.10 Typical details of dry-well pump station
98
Figure 5.11 Fine Bubble Diffuser Air – Extended Aeration System
113
Figure 5.13 Deep Shaft Activated Sludge System
116
Figure 5.12 Oxidation Ditch Activated Sludge System
Figure 5.14 Rotating Biological Contactor (RBC) Systems
Figure 5.15 Typical Process Flow Diagram for Biological Nutrient Removal System
Figure 5.16 Schematic illustration of ultraviolet disinfection system with stilling plate for flow conditioning and elongated weir for level control
vi
119
114 119
121 126
Figure 5.17 Profile schematic of lamp modules relative to inlet and outlet structure Figure 5.19 Chemical-feed system schematic
127
146
Figure 5.20 Sludge Treatment and Disposal Strategy
Section 6
Figure 5.21 Typical Roof Details for Covered Sludge Drying Bed
6.1
6.3
6.2
6.4
6.5
6.6
6.7
6.8
6.10
6.12
6.14
6.9
6.11
6.13
6.15
6.16
6.17
6.18 6.19
6.20
6.21
6.22
6.23
6.24
Table 6.1 Table 6.2
Table 6.3
Requirements for Ancillary Facilities
127 143
Introduction
149
Mess Facilities and Ablutions
150
Water Supply and Wash Water Roads and Access Drainage
Fencing and Security
Beautification Zone and Landscape
Stores and Workshops Spares
Yard Lighting
Sampling Facilities
Auto Restart Facilities Safety Facilities Doors
Fire Hydrant
Power Supply
Internal Sanitation (Toilet) Lifting Requirement Ventilation
Process Water Aesthetic
Close Turfing
Standard Roofing and related requirement
Painting
149
152 153
154 159 159
159
161 162
162 163 163
163 164
164
164 165
168 168 168 168
169
Minimum Number of Recommended Water Stand 150 Pipe and Location Spare Part 161 Numbers of Unit and Location of Compound Lighting
161
vii
Table 6.4
Common ventilation rates
167
Figure 6.1
Standard Details for Stand Pipe
151
Table 6.5
Figure 6.2
Figure 6.3
Figure 6.4
Figure 6.5
Figure 6.6
Figure 6.7
Figure 6.8
Figure 6.9
Painting System Index – Colour Standards Typical for Administration and Mess Facilities Building Typical Details of Road Pavement
Typical Road Section of Site Road
Typical Drawing of Brickwall Fencing and Gate Brickwall Fencing Precast Fencing
Masonry Fencing
Typical Details of Compound Lighting
Figure 6.10 Typical Detail of Guard Rail
Figure 6.11 Typical Detail of Lifting Davit
Figure 6.12 Typical Detail of A-Frame Lifting Facilities Section 7
7.1
170
152
152
152
155
156
157
158
162
171
172
172
Special Requirements Temporary Treatment Plants
175
7.1.2 Category 1: Temporary Treatment Plant for Upgrading of Facilities
175
7.2
7.3
7.4
7.1.1 Definition
7.1.3 Category 2: Temporary Plants for New Housing Development
176
7.2.1 Introduction
172
Treatment Plants Located Within Buildings
179
7.2.2 Specific Guidelines and Requirements
180
Fully Enclosed Treatment Plant 7.3.1 Definition
7.3.2 General Requirements
7.3.3 Specific Requirements
Covered and Buried Treatment Plants 7.4.1 Definition 7.4.2 General
7.4.3 Specific Requirements for Covered or Buried Plants under 5,000 PE or Less
viii
175
181
185
185 186
194
194
194
194
7.5
Guidelines for Homestead Developments
7.5.1 Single Developments up to 30 Units or 150 PE in Total
197 197
7.5.2 Single Developments Over 30 Units in Total with Average Housing Density Greater Than Five Units per Hectare
197
7.5.3 Single Developments Over 30 Units in Total with Average Housing Density Less Than Five Units per Hectare
197
Non-Compliance with Standards
198
7.6.2 Types of Incident’s that Can Cause Treatment Plant Failure
198
198
7.6
7.7
7.8
Section 8
8.1
8.3
8.2
8.4
7.6.1 Introduction
Energy Saving
Recycle and Reuse Package Sewage Treatment Plant
201 201
Definition
205
Design Requirement
206
Land Area Requirement Components of Package Sewage Treatment Plant
8.4.1 Layout, Piping and Arrangement of Prefabricated Biological Treatment System
205
206 206
8.4.2 Prefabricated Tanks
206
Appurtenances
208
8.5
8.6
8.4.3 Process Treatment Units/Components 8.5.1 Piping system
8.5.2 Pumping System 8.5.3 Diffuser
8.5.4 Flow Distribution Chamber
8.5.5 Manhole Cover/Inspection Chamber Cover 8.5.6 Anchor System Loading 8.5.7 Landscaping
8.5.8 Odour Treatment
8.5.9 Ancillary Facilities Marking and Labelling
207 208 209
210
210 210 211 211 211
212 212
ix
Table 8.1
Minimum Design Life Span of Package Sewage Treatment Plant Components
206
Technical Requirements of Pumping System
209
Table 8.2
x
Table 8.3
Table 8.4
Recommended Number of Tanks and Effective Volume Consideration for Various Unit Processes
207
Technical Requirements of Manhole Cover
210
Appendices Appendix A Table
Table A1
Table A2
Table A3
Table A4
Table A6
Table A5
Table A7
Table A8
Contaminants of Concern in Sewage Treatment
216
Major Biological Treatment Processes Used for Sewage Treatment
218
Typical Composition of Untreated Domestic Sewage
217
Interim National River Water Quality Standards for Malaysia 220 River Clarification
221
Permissible limits for potentially toxic elements in soil
223
The Occupational Safety and Health Act 514, 1994 - Brief Summary of Contents Options for disposal of Sludge and reuse of bio-solids
Appendix B References
222
224
Malaysian Standards
227
European Standard
229
British Standard
ASTM Standard
AS Standard
Other Reference Materials
Other Guidelines in This Set
Appendix C Supervisory Control and Data Acquisition System (SCADA)
228
231 232
232 232
C-1
Introduction: Overview
237
C-3
General Requirements
238
C-2
C-4
C-5
C-6
C-7
C-8
C-9
C-10 C-11
C-12
C-13
Purpose
Architecture
SCADA Requirement Operator Interface Database
Alarm/Event Management Historian
Graphical Trending Report Format Security
Scripting
238 238
239 240
241 241 243
243 244
244
245
xi
C-14
Interfaces
245
C-16
Web Server
245
C-15
Distributed Server Architecture
245
C-17
Digital Video Monitoring
246
C-19
Application Report
247
C-18
C-20
C-21 C-22
Integrated Maintenance Management Application Programming Interface User Documentation
Specifications and Sizing
246
247
248 248
Appendix D Duty and Standby Requirements Table D.1
Duty and Standby Requirements for Activated Sludge Systems (Utilising Diffused Aeration)
268
Table D.3
Duty and Standby Requirements for Rotating Biological Contactor Systems
270
Table D.2
Table D.4
Duty and Standby Requirements for Activated Sludge Systems (Utilising Mechanical Surface Aerator)
269
Duty and Standby Requirements for Trickling Filter Systems 271
Appendix E Glossary of Abbreviations
xii
Glossary of Abbreviations
275
Section 1 Introduction and General Planning Requirements
Introduction and General Planning Requirements
2
Volume 4
Malaysian Sewerage Industry Guidelines
Introduction and General Planning Requirements
1.1
Purpose of This Volume This volume sets out the requirements of the National Water Services Commission (SPAN) (referred to as the Commission in this document) for the planning, design and construction of sewage treatment plants. This volume contains the following: a) b) c) d) e) f) g)
An overview of considerations and criteria for sewage treatment plant design. Effluent discharge standards requirements and the capacity of different sewage treatment processes to meet these standards. Requirements for the siting and sizing of sewage treatment plants. Requirements for each stage of sewage treatment.
Minimum requirements for facilities ancillary to a sewage treatment plant. Other special requirements for temporary treatment plants, treatment plants within buildings, homestead developments and exemptions for non-compliance with standards. Requirements of sludge treatment process and disposal.
The owner must comply with the requirements set out in this volume when submitting an application for approval to the Commissioner. This volume does not cover any aspect other than Sewage Treatment Plant requirements. All internal plumbing approvals need to be approved by Local Authorities.
1.2
Who Should Use This Volume This Volume is primarily for owners, developers, consulting engineers and Public Authorities whose developments include sewage treatment plants.
1.3
Related Reference Material This Volume does not cover all aspects of design and construction of sewage treatment plants. Where information is not covered in this volume, the designer shall follow the requirements given in MS 1228. However, the information in this Volume shall take precedence over MS 1228 where similar aspects are covered in these documents or where there is conflicting information between the two documents.
Sewage Treatment Plants
Volume 4
3
Introduction and General Planning Requirements
The procedures for certification of sewerage services are given in the Malaysia, Volume 2 Sewerage Works Procedures. All Standards references adopted during this revision exercise are compiled and given in Appendix B.
1.4
General Planning and Design Approval Requirements The application procedures for sewage treatment plants approval shall follow the requirements given in MSIG Volume 2. In general, the application for approval of a treatment plant shall include: a) b) c)
d)
e) f) g)
h) i) j) k) l)
4
Sufficient land area for the sewage treatment plants plus additional area to allow for extensions to the plant, where necessary. Land of suitable configuration shall be provided. Sufficient buffer zones.
The location of a sewage treatment plant in relation to a particular catchment area. The plant unit processes shall be located at an elevation which is not subject to flooding/wave action, or shall otherwise be adequately protected against all flooding/wave action. Sufficient topographic features shall be included to indicate its location in relation to streams and the point of discharge of the treated effluent. Schematic flow diagrams showing utility systems serving the plant processes and the flow through various plant units.
Pipeworks, including any arrangements for bypass from individual units. The direction of flow and the content in the pipes shall also be clearly and permanently painted onto all exposed piping works. Hydraulic profiles showing the flow of sewage, supernatant liquor, and sludge.
Location, dimensions and elevations of all existing and proposed plant facilities.
Capacity of the effluent receiving drain/water course shall be able to cater for additional discharge flow from the treatment plant.
Consideration for odour and noise mitigation and control through good facility design, effective operation, containment, collection and treatment.
Point of discharge of treated effluent (effluent outfall) and elevations
Volume 4
Malaysian Sewerage Industry Guidelines
Introduction and General Planning Requirements
m) n) o) p) q) r)
s) t)
u) v)
w)
Type, size, features, and operating capacity of all pumps, blowers, motors and other mechanical devices together with manufacturer catalogues. Minimum, average and maximum hydraulic flows, velocities and top water level in profiles. Accessibility, landscaping and fencing. Flow measurement facilities.
Materials, dimensions and specifications.
Ground conditions including levels, type, groundwater level and safe bearing pressure of foundation.
Details of foundation and other structural design. Slope protection works are required, where applicable. All other components of the sewage treatment plant.
A technical report, which covers the ‘whole life cost’ evaluation of the plant. Process and instrumentation diagram. Mass balance calculation
x)
Clean and legible detailed drawings in standard format
z)
Where required, an EA or EIA report is needed to identify, predict, evaluate and communicate information concerning the adverse and beneficial impacts of the proposed treatment plant.
y)
aa)
1.5
of high and low water levels of the receiving watercourse to which the plant effluent is to be discharged.
Operation and Maintenance needs of the plant to be addressed at the early planning stage.
HAZOP requirement is necessary to identify the safety and operability deficiencies in the design and operation of the treatment plant.
Guidelines for Design Calculations Design calculation for all unit processes shall be in sequence starting from inlet works to biological treatments and sludge treatments as shown in Figure 5.1. The calculation shall include: a) b) c)
Sizing of each unit processes and all mechanical equipment involved. Mass balance for overall system and each unit process. Influent values.
Sewage Treatment Plants
Volume 4
5
Introduction and General Planning Requirements
d) e) f) g) h)
Design influent and effluent values in compliance with Section 3.3.2. Treatment plant shall be designed based on design flow. Hydraulic profile across the treatment units to be indicated onto to the drawings. Each unit process must comply with the design parameters set in Section 5. Calculation of PE to be based on Table 1.1.
Table 1.1 Recommended Population Equivalent Type of Premises/ Establishment
Population Equivalent (Recommended))
Residential
5 per house
Commercial:
3 per 100 m2 gross area
Includes offices, shopping complex, entertainment/ recreational centres, restaurants, cafeteria, theatres Schools/ Educational Institutions: - Day schools/ Institutions
0.2 per student
- Partial residential
0.2 per non-residential student
- Fully residential
1 per student
1 per residential student
Hospitals
4 per bed
Hotels with dining and laundry facilities
4 per room
Factories, excluding process water
0.3 per staff
Market (wet type)
3 per stall
Market (dry type)
1 per stall
Petrol kiosks/Service stations
15 per toilet
Bus terminal
4 per bus bay
Taxi terminal
4 per taxi bay
(Ref: Malaysian Standard 1228)
6
Volume 4
Malaysian Sewerage Industry Guidelines
Introduction and General Planning Requirements
Table 1.1 - Recommended Population Equivalent (Cont) Type of Premises/ Establishment
Population Equivalent (Recommended)
Mosque/ Church/ Temple
0.2 per person
Swimming pool/ Sports complex
0.5 per person
Stadium
0.2 per person
Public toilet
15 per toilet
Airport
0.2 per passenger 0.3 per employee
Laundry
10 per machine
Prison
Golf course (Ref: Malaysian Standard 1228)
1.6
1 per person 20 per hole
Guidelines for Drawings All drawings shall be of standard format and orientation. The drawings required include: a) b) c)
d)
e)
Overall development plan showing the whole sewerage system and plant location. Site layout plan showing the arrangement of the plant, buffer zone, internal set backs and all neighbouring developments.
Site layout plans showing all the process units, main pipe runs, electrical conduit corridors, site services (water, drains, lighting, other services), roads and paving, landscaping, buildings, fencing and finished level contours (or spot levels). The set out and overall dimensions of the plant shall also be shown.
Site elevations of the plant with at least one section through the plant in each direction. These sections shall extend at least 30 m from the plant boundary and include an indication of the surrounding development (in block form only). Process and instrumentation diagram (P&ID) showing all tanks, pipes, channels, valves, mechanical equipment, instrumentation and control loops. The P&ID can also act as a summary of the design. It provides key details of each piece of equipment, tank, piping, valves and instruments.
Sewage Treatment Plants
Volume 4
7
Introduction and General Planning Requirements
f)
g) h)
i) j)
8
Hydraulic profile showing all hydraulic pathways through the plant including bypasses. Information to be shown includes pipe sizes, invert levels, flow velocities, tank coping level, top water level and freeboard. Top water level and velocities at minimum flow, average flow and peak flow under design load must be clearly indicated. Schematic flow diagrams and mass balances showing flow through all process units in the plant.
General arrangement drawings of each unit process. These drawings shall be in sufficient details to clearly describe the shape, size and function of each unit. The drawings shall show the structure of the unit, piping, valves and fittings, instrumentation, mechanical and electrical equipment, buildings, handrails, stairs, ladders, step irons, site services such as water and lighting, adjoining paving, roadworks, fencing, drainage, etc. Drawings of all items should show the elevations, plan view and sectional view (horizontally and vertically), where applicable. Details are required of any object that would affect the operation or maintenance of the plant that is not covered by a standard drawing. Required to use standard symbols and legend formats for all drawings.
Volume 4
Malaysian Sewerage Industry Guidelines
Sewage Treatment Plants
Volume 4
Sewage Treatment Plants
Volume 4
0.2m
0.4m
0.6m
0.8m
1.0m
1.2m
1.4m
1.6m
1.8m
2.0m
F.G.L.
-0.6M PRIMARY PUMPING VALVE SCREEN STATION CHAMBER
-0.4m
-0.2m
FGL
F.F.L.
PRIMARY PUMPING VALVE SCREEN STATION CHAMBER
I.L.
F.G.L.
SECONDARY SCREEN
SECONDARY SCREEN
F.G.L.
CL
I.L.
AERATION TANK
AERATION TANK
TWL
CL
I.L.
TWL TWL F.G.L.
CLARIFIER DISTRIBUTION CHAMBER
CLARIFIER DISTRIBUTION CHAMBER
F.G.L.
HYDRAULIC PROFILE
I.L.
CLARIFIERS
CLARIFIERS
TWL TWL TWL TWL
F.G.L.
NOTES :
OUTFALL MEASUREMENT FLUME
HIGHEST FLOOD WATER LEVEL NORMAL WATER LEVEL
NORMAL WATER LEVEL
FLOOD LEVEL IN RECEIVING WATERCOURSE
OF ACTUAL PLANT DESIGN AND ACTUAL SITE SURVEY.
2. ACTUAL LEVELS SHALL BE DETERMINE FROM HYDRAULIC CALCULATIONS
1. THE LEVELS SHOWN ARE FOR INDICATIVE PURPOSES ONLY.
CHLORINE CONTACT TANK
OUTFALL MEASUREMENT FLUME CHLORINE CONTACT TANK
F.G.L.
Introduction and General Planning Requirements Introduction and General Planning Requirements
Figure 1.1 Typical Hydraulic Profile Figure 1.1 – Typical Hydraulic Profile
9
Page 7
Introduction and General Planning Requirements
Figure 1.2 Typical Process and Instrumentation Diagram
10
Volume 4
Malaysian Sewerage Industry Guidelines
Sewage Treatment Plants
Sewage Treatment Plants
Volume 4
Volume 4
Pump
Pump
Raw Sewage
Raw Sewage
Screen
PUMPING STATION (EXISTING)
RAW SEWAGE
SS =
BOD =
Q=
RAW SEWAGE M
SS =
BOD =
Q=
RAW SEWAGE
SS =
BOD =
Q=
=
Screen
Filtrate =
Q
SCREEN CHAMBER
=
M
M
=
Filtrate =
= =
Q BOD
Skimmer
Water =
Q
Oil Discharge Tank
= = =
Q BOD SS
Floor Drain Pit
Transfer Pump
GREASE CHAMBER
Oil & Grease Pump
Grit Pump
Grit Classifier
Vortex
=
Oil Holding Tank
SS
BOD =
Q
GRIT CHAMBER
Mixer Pump
Balancing
BALANCING TANK
= = =
Q BOD SS
= =
=
Q BOD SS
=
MLSS =
Q
Aerator
Supernatant Decanter
REACTOR
SEQUENCING BATCH
=
=
=
= = =
Q BOD SS
HOLDING TANK
SLUDGE
Pump
Waste Sludge
TANK
MEASURING
SS
BOD
Q
BLOWER
Introduction and General Planning Requirements Introduction and General Planning Requirements
Figure 1.3 Typical Process Flow Diagram Figure 1.3 Typical Process Flow Diagram
11
9
Introduction and General Planning Requirements Introduction Introductionand andGeneral GeneralPlanning Planning Requirements Requirements
Figure 1.4 Typical Mass Balance Diagram Figure Balance Diagram Diagram Figure 1.4 1.4 –– Typical Typical Mass Balance INFLOW INFLOWPARTICULARS PARTICULARS QQ = = BOD BOD= = 10% 10%SS SStotobe beremoved removed SS= = SS PHYSICALTREATMENT TREATMENT PHYSICAL PRIMARYSCREEN SCREEN 1)1)PRIMARY SECONDARYSCREEN SCREEN 2)2)SECONDARY
QiQi= = BOD= = BOD SS= = SS
Qi ++ Qr Qr ++ Qw Qw QQ == Qi BOD == BOD SS == SS
Qe Qe == BOD BOD == SS SS ==
SECONDARY SECONDARY CLARIFIER CLARIFIER
AERATIONTANK TANK AERATION MLSS= = MLSS
OUTLET OUTLET
OVERFLOW OVERFLOW SS SS CONC CONC== BOD BOD ==
Qr Qr++Qw Qw== BOD = BOD = SS = SS =
Qr, Xr Qr, Xr Qr = X Qi = Qr = X BOD = Qi = BOD = SS = SS =
AEROBIC DIGESTED AEROBIC DIGESTED SLUDGE HOLDING TANK SLUDGE HOLDING TANK
Qw = Qw == BOD BOD SS == SS == 1%DS 1%DS = SLUDGE THICKENER SLUDGE THICKENER
Qw = BOD Qw == SS == BOD 4%DS SS = 4%DS =
Qw OVERFLOW = Qw OVERFLOW =
Sludge to be pumped to Sand Drying Bed For Dewatering to 25% to Dry SolidDrying Bed Sludge to be pumped Sand For Dewatering to 25% Dry Solid
Figure 1.5 Typical Electrical Single Line Diagram Figure 1.5 - Typical Electrical Single Line Diagram Figure 1.5 - Typical Electrical Single Line Diagram
SPARE
SPARE
TO COMPOUND LIGHTING (2 nos) TO COMPOUND LIGHTING (2 nos)
TO 13A SOCKET OUTLET TO 13A SOCKET OUTLET
24T
24T
20A
20A
0 -3 0 A 0 -5 0 0 V
0 -3 0 A 3 0 A T P + N 1 0SK/s AwM C C B 4 0 /0 .3 A 4 p R C C B
10A
0 -5 0 0 V
10A
S /s w S /s w 4 0 /0 .3 A 4 p R C C B
20A
3x5A
TO 36W FLOUERECENT LIGHT TO 36W FLOUERECENT LIGHT
B 6A
Y
R SY/s wB
20A
RAW SEWAGE SUBMERSIBLE RAW SEWAGE SUBMERSIBLE PUMP PUMP NO.2 (2.4kW) Using 4c x 2.5mm ARM Cable NO.2 (2.4kW) Using 4c x 2.5mm ARM Cable
TO CONTROL CIRCUIT TO CONTROL CIRCUIT 2 x sq. 1.5mm Using 2 Using x 1.5mm PVCsq. PVC R
3x5A
0 -4 0 A S /s w 0 -5 0 0 V S /s w PSR P HA SE S EQ UENC E R E L A Y0 -4 0 A S /s w 4 0 /0 .3 A 4 p R C C B PSR P HA SE S EQ UENC E R E LA Y 40A TP N 10KA M C C B 4 0 /0 .3 A 4 p R C C B
3x5A
D IS T R IB U T IO N B O X F O R L IG H T IN G A N D P O W E R D IS T R IB U T IO N B O X F O R L IG H T IN G A N D P O W E R
6A
0 -5 0 0 V
TOR
TOR
B
w YS /sB
TPN20A TPN20A TOR MCB MCB DOL DOL A A
20A SPN20A SPN MCB MCB
Y
TPN20A TPN20A TOR MCB MCB DOL DOL A A
R
S
S
SPN6A SPN6A MCB MCB
13A Socket Outlet Outlet 13A Socket Using 2Using x 2.5mm sq. PVCsq. PVC 2 x 2.5mm
To Control Circuit To Control Circuit E. STOP x 1.5mm sq. PVC E. STOP Using 2Using 2 x 1.5mm sq. PVC
EQ Pump no. 2 (0.6kW) EQ Pump no. 2 (0.6kW) Using 4c x 2.5mm ARM Cable Using 4c x 2.5mm ARM Cable R
3x5A
D
D
PSR
S
6A SPN SPN MCB 6APSR MCB
EQ Pump no. 1 (0.6kW) EQ Pump no. 1 (0.6kW) Using 4c x 2.5mm ARM Cable Using 4c x 2.5mm ARM Cable
S
TOR
D
D
16A TPN TOR TPN MCB 16A DOL MCB DOL
Air blower motor no.2 (3.7kW) Air blower motor no.2 (3.7kW) Using 4c x 2.5mm ARM Cable Using 4c x 2.5mm ARM Cable
TOR
TOR
S
20A TPN TOR MCB 20A TPN DOL MCB DOL
20A TPN TOR MCB 20A DOL TPN MCB DOL
S
TOR
D
D
16A TPN TOR TPN MCB 16A DOL MCB DOL
Air blower motor no.1 (3.7kW) Airx blower no.1 (3.7kW) Using 4c 2.5mmmotor ARM Cable Using 4c x 2.5mm ARM Cable
M O T O R S E .Q P U M P S A N D S S T P U M P
RAW SEWAGE SUBMERSIBRE PUMP PUMP RAW SEWAGE SUBMERSIBRE NO.1 (2.4kW) Using 4c x 2.5mm ARM Cable NO.1 (2.4kW) Using 4c x 2.5mm ARM Cable
S IN G L E L IN E L A Y O U T D IA G R A M F O R R A W S E W A G E S U B M E R S IB L E P U M P S IN G L E L IN E L A Y O U T D IA G R A M F O R R A W S E W A G E S U B M E R S IB L E P U M P
S IN G L E L IN E L A Y O U T D IA G R A M F O R A IR B L O W E R M O T O R S E .Q P U M P S A N D S S T P U M P S IN G L E L IN E L A Y O U T D IA G R A M F O R A IR B L O W E R
4 0 /0 .1 A 2P R CCB
E
S P +N 30K A 1 04 0K/0 A .1 MAC C B 2P R CCB U S IN G 4 C x 1 6 m m P V C /S W A P V C A R M . C A B L E U S IN G 4 C x 1 0 m m P V C /S W A /P V C A R M . C A B L E U S IN G 2 C x 6 m E m P V C /S W A /P V C A R M . C A B L E S P +N 30K A 40A TP N 10KA M C C B 30A TP +N 10KA M C C B 10 KA M CCB 40A TP+N 30A TP +N 30A SP+N U S IN G 4 C x 1 6 m m P V C /S W A P V C A R M . C AMBCL C EB U S IN G 4 C x 1 0 m m P V C /S W A /P V C A R M . CMACBCLB E U S IN G 2 C x 6 m m P V C /S W A /P V C A R M .MCCAC BB LE R
40A TP+N MCCB
Y
B
6A 3 x 6 0 /5 A
3 x 6 0 /5 A
0 -50 0V
R 6A PSR
V .s .s w Y B
30A TP +N MCCB
E
E
30A SP+N MCCB
0 -6 0 A
V .s .s w 0 -50 0V V .s wS E S E Q U E N C E P .s HA R E L A Y 0 -6 0 A
.sC wB 6 3 /0 .3 A 4 pV .s RC PSR PHASE SEQUENCE 6 0 A T P + N 2R5EKLAA Y (4 P O L E ) M C C B
E
6 3 /0 .3 A 4 p R C C B 6 0 A T P + N 2 5 K A (4 P O L E ) M C C B 415 V S U P P LY 3 PHASE T N B M E T E R IN G PANEL M U L T IC O R E A R M O U R E D C ABLE TO T N B R E Q U IM E N T
415 V S U P P LY 3 PHASE
E
S IN G L E L IN E L A Y O U T D IA G R A M F O R M A IN S W IT C H B O A R D
S IN G L E L IN E L A Y O U T D IA G R A M F O R M A IN S W IT C H B O A R D
T N B M E T E R IN G PANEL M U L T IC O R E A R M O U R E D
OR O M IN C O M IN G S C U APBPLLEYT F T N B R E Q U IM E N T M A IN D B 4 1 5 V
IN C O M IN G S U P P L Y F R O M M A IN D B 4 1 5 V
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10
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Section 2 Design Overview
Design Overview
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2.1 2.1.1
Treatment Plant Classification Classification by Biological Treatment Processes The microorganisms in sewage treatment can be grown in a form of fixed film, suspension or a combination of both. Hence, biological treatment processes for sewage treatment works can be classified under one of the following headings: a)
Attached Growth Processes
c)
Combined Processes (Hybrid)
b)
2.1.1.1
Suspended Growth Processes
Attached Growth Processes In an attached growth process, the active microorganisms grow and attach on the mobile or immobile medium (rock or plastic) that is in contact with sewage. The surface area of the biomass is used as the practical measure of the total organism activity. Types of attached growth processes include: a)
Trickling Filter (TF)
c)
Submerged Biological Contactor (SBC)
b) d) e) 2.1.1.2
Rotating Biological Contactor (RBC) Fluidised Bed
Packed Bed Reactor
Suspended Growth Processes In a suspended growth process, active microorganisms remain in suspension in the sewage and their concentration is usually related to mixed liquor suspended solid (MLSS) or mixed liquor volatile suspended solid (MLVSS). This system was developed as a result of studies that showed that if sewage is aerated over a long period of time, the organics in the sewage are removed by the active microorganisms grow during the process. Types of suspended growth processes include: a)
Waste Stabilisation Pond System
c)
Conventional Activated Sludge (CAS)
b)
Aerated Lagoon
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Design Overview
d) e) f) g) h) 2.1.1.3
Extended Aeration (EA) Oxidation Ditch (OD) Deep Shaft (DS) Sequencing Batch Reactor (SBR) Any other treatment processes which comply with the design principles of one of the above processes.
Hybrid Processes - Attached Growth with Suspended Growth Recent developments in sewage treatment technology include the combination of various attached growth and suspended growth processes to obtain the best performance and most economical treatment of sewage. One of the advantages of Hybrid Process is the process combines the stability and resistance to shock loads of an attached growth process and the capability to produce high-quality effluent of an suspended growth system. Hybrid processes can be used to upgrade existing attached growth and suspended growth process, in particularly plants with high suspended solids in the final effluent due to poor solids settlement in the final clarifier.
2.1.2
Classification by Treatment Plant Capacity Sewage treatment plants are also classified in accordance to the design capacity in terms of population equivalent (PE). Table 2.2 tabulates 4 clarifications to be adopted. Table 2.1 - Classification by Treatment Plant Capacity Classification
PE
Class 1 Class 2 Class 3 Class 4
≤1000 1001 – 5000 5001 – 20000 > 20000
2.2
Treatment System Selection / Design
2.2.1
General Selection Considerations The following factors must be considered when selecting a sewage treatment process:
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Process
The applicability of a process is evaluated on the basis of past experience, data from full-scale plants and pilot data from treatment plant studies. If new or unusual conditions are encountered, pilot-plant studies are necessary.
Flow Range
The selected process should be matched to the expected flow range.
Flow Variation
Most unit operation and processes work best with a constant flow rate, although some variation can be tolerated. If the flow variation is too great, flow equalisation may be necessary.
Influent Sewage
The characteristics of the influent will affect the types of processes to be used and the requirements for their proper operation.
Inhibiting Constituents
Identify the constituents present that may be inhibitory, and the conditions they are in.
Climatic Constraints
Temperature affects the rate of reaction of most treatment processes.
Reaction Kinetics and Reactor Selection
Reactor sizing is based on the governing reaction kinetics. Data for kinetic expressions are usually derived from experience, literature and results of pilot-plant studies.
Performance
Performance is usually measured in terms of effluent quality, which must be consistent with the given effluent discharge requirements.
Treatment Residuals The types and amounts of solid, liquid and gaseous residuals produced must be known or estimated. Sludge Handling Constraints
In many cases, a treatment method should be selected only after the sludge processing and handling options have been explored.
Environmental Constraints
Nutrient requirements must be considered for biological treatment processes. Environmental factors, such as the prevailing winds and wind directions, may restrict the use of certain processes, especially where odours may be produced.
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Design Overview
Chemical Requirements
Classify chemicals and amounts that must be committed for a long period of time for the successful operation of the unit operation or process.
Energy Requirements
The energy requirements, as well as probable future energy costs, must be known if cost-effective treatment systems are to be designed.
Other Resource Requirements
Identify additional resources that must be committed to the successful implementation of the proposed treatment system using the unit operation or process in question.
Reliability
Consider the long-term record of the reliability of the unit operation or process under consideration.
Complexity
Evaluate the complexity of the process to operate under routine conditions and under emergency conditions such as shock loadings, as well as the level of training the operator must have to operate the process.
Ancillary Processes
Identify the required support process and the effect on the effluent quality, especially when they become inoperative.
Compatibility
The unit operation or process shall be used successfully with existing facilities, plant expansion and modifications.
Odour and Noise
Odour and noise pollution should be minimised to the lowest possible level.
Aesthetics
The selected treatment process should aesthetically suit the development site.
Safety and Operability
The chosen treatment process shall be designed with utmost care to facilitate safe operations at all times as well as to incorporate safety features for the protection of operators. See Section 2.3.
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Land Requirements
A more compact plant component may perform equally well to a component taking up more land and thus would be preferential, provided there was no significant component cost differences.
Ease of Operation and Maintenance
This will dictate whether plant has to be continuously or intermittently operated and whether skilled or relatively unskilled personnel would be required to carry out the operations and maintenance works.
Modulation
Modulation refers to the ability of process units to be expanded in tandem with flow increases. Modulation minimises the time that the plant sits idle before utilisation and lowers initial capital outlay.
Standardisation
This brings about economics on design effort, material procurement, quality checks, spares and maintenance costs.
Adaptability
Adaptability refers to the ability to readily upgrade or uprate the performance of a treatment plant with relatively minor extra works.
Sludge Management This is an important aspect that needs careful evaluation. Treatment systems that minimise waste sludge production, and which produce a relatively stable sludge should be given preference. See Section 5.12 Overall Cost
Sewage Treatment Plants
This will include considerations of capital, operation and maintenance costs. Spare parts costs related to maintenance can be hidden costs that also need consideration, particularly where there may be long time delays obtaining parts or specialist inputs are required.
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Design Overview
2.2.2
Design Stages
The design of a sewage treatment plant comprises the following stages: Process Design
In this stage, a suitable sequence of processes are selected to meet stipulated final effluent requirements for the plant concerned.
Functional Design
In this stage, calculation of capacities required are conducted for all major units, channels, pumps and pipework and also definition of control requirements. These include designs for hydraulic, organic and solid loadings.
Detailed Design
In this stage, structural design of units and channels, detailing of pipelines, fittings and control valves, and selection of mechanical, electrical and control equipment are conducted.
2.2.3
Detailed Design Criteria For the following characteristics and requirements of a treatment plant, the designer needs to consider a number of detailed design criteria: a)
Biochemical characteristics
c)
Hydraulic characteristics
b) d) e) f) 2.2.3.1
Physical characteristics
Mechanical & engineering requirements Structural requirements
Constructional characteristics
Biochemical Characteristics These involve the consideration of the following parameters: a)
Chemical characteristics of sewage
c)
Optimal substrate concentration
b) d) e) f)
g)
20
Good activity between microorganisms and waste materials Operational stability (half-life and activity decay profile) Availability of suitable nutrients
Maintenance of favourable environment
Effect of filamentous growth & sludge bulking
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h)
Effect of dissolved oxygen
j)
Minimum and maximum residence times
i)
k) l)
m) n) o) p) q) 2.2.3.2
Productivity in lifetime usage By-product formation
pH and temperature sensitivity Storage stability
Reactor effluent quality-composition, colour, odour, etc. Sludge production and frequency of desludging Effective material balance analysis
Development of biochemical kinetic coefficient through pilot plants
Physical Characteristics These involve the examination of: a)
Particle shape and size distribution
c)
Swelling behaviour
b) d) e) f)
g) h) 2.2.3.3
Dry and wet bulk density Compressibility
Cohesion and particle attrition Settlement
Floc formation
Settling velocity and sedimentation
Hydraulic Characteristics These involve the examination of: a)
Hydraulic velocities in all unit processes
c)
Axial dispersion and channelling
b) d) e) f)
g) h)
Mode of flow, upflow versus downflow
Pressure drop and head loss through plant
Residence time distribution and retention time Stratification
Length to width ratio
Minimum velocity for onset of fluidisation
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Design Overview
i) j) 2.2.3.4
Weir loadings
Overflow rate
Construction Characteristics These involve the examination of: a)
Ground conditions and soil characteristics
c)
Type of plant depending on density and type of community to be served
b)
d) e) f)
g) h) i) 2.2.3.5
b) c)
d) e)
Delivery and construction time
Recommended maintenance requirements Start-up time and procedure Noise levels
Technical capability to construct, operate and maintain the system
Wall, slab, beams, columns and structure for sewage treatment plant shall be in reinforced concrete. Wall shall have minimum thickness of 225 mm.
Special foundation shall be provided where necessary. Proper jointing to prevent breakage and leakage.
Water retaining and slope protection where applicable.
Mechanical & Electrical Requirements a) b) c) d)
22
Distance to nearest habitation
Structural Requirements a)
2.2.3.6
Land availability
The design shall simplify the equipment required, control system, maintenance and operational procedures, while fulfilling the intended performance and standard of service. Equipment selected shall be from manufacturers (and models) approved by the Commission.
Equipment, cable and cabling design and installation shall follow IEE and TNB requirements.
Foundations shall be structurally designed and anchored to withstand all loads imposed by the equipment. Reinforced concrete foundations are preferred. Volume 4
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e) f) g) h) i) j)
k) l)
2.3
Joints shall be provided in all piping to allow removal of equipment, meters, valves and other special items without causing dismantling of the pipeline.
Equipment shall be equipped with safety protection (i.e. emergency stop button, warning signage & etc.). See Section 4.5. Pipeworks shall be neatly arranged and properly supported.
Appropriate type of control system provided for the treatment plant. See Section 4.5.
Construction materials to be protected against corrosion due to high humidity. Earthing and protection against lightning.
System manuals, plant function diagrams, electrical system, electrical circuit and instrument loop diagrams shall be provided before the plant is pre-commissioned. Detailed and shop drawing for equipment, instrumentation and cable & cabling shall be provided.
Safety and Health Principles Throughout the design, construction, commissioning, operation and maintenance stages of a project, the following safety principles shall apply:
2.3.1
General Safety a) b) c) d) e) f) g)
Malaysian Safety and Health legislations, standards and procedures under Occupational Safety and Health Act (OSHA) 1994, Factories and Machinery Act 1967 and etc. shall be followed. Workforce, contractors, visitors and the public shall be safeguarded against hazards, risk of serious injury and disease. Adequate training shall be made available for the use of all related equipment.
Appropriate training for end users to be identified and stipulated in construction and procurement documents. Appropriate responsibilities to be assigned throughout each stage of a project.
Safety consciousness to be promoted by effective internal communication, signs and media. Safety performance shall be easily audited during operation and maintenance.
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h) i) j) k)
l) m) n) o)
2.3.2
Risk assessment to be undertaken at design of projects and selection stage of procurement. Safety information and operating documents to be provided by suppliers.
Emergency contact list, showing telephone numbers of key personnel and emergency services during office hours and out of office hours, to be circulated to all parties involved in a project.
Plant (certain sized) should be provided with Emergency Response Plan (ERP) All treatment plants, installation and construction sites, shall be provided with perimeter fencing adequate to protect the public from entry. All fencing shall be securely fixed and inspected. All treatment plants, installations and construction sites shall have adequate warning signs at or near the perimeter.
Access to construction sites shall be controlled to prevent unauthorised access.
Structural Safety a)
Safe access to all working areas to be provided.
c)
Any confined space requiring routine person entry, which contains sewage, sludge or other foul water, to be ventilated.
b)
d) e) f) g) h) i)
24
All accidents or potential serious incidents to be reported and investigated.
Routine requirement to enter confined spaces to be eliminated, where practicable.
Concrete slabs over wet wells, tanks and chambers shall have double steel reinforcing.
Lifting eyes and bolts for slabs to be stainless steel or any other durable and non-corrosive material. Protection against falling (i.e. handrail, kick plate and toe plate) to be provided.
Within plants and installations, all wells, sumps, channels, chambers, tanks, etc. containing any liquid shall be covered, walled or railed. Major hazards to be identified and posted on site.
Protection and counter measures against spillage of dangerous chemicals to be provided.
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j) k) l)
Permanent staircase shall be provided at inlet sumps, inlet wells, inlet chambers and dry-wells. Steps and riser shall follow UBBL Standard. Adequate lifting facility shall be provided for heavy equipment, which requires maintenance work. Blower room shall not share common wall and foundation with the control and genset room
2.3.3 Equipment and Electrical Safety a) b) c)
d) e) f) g) h) i)
j)
Electrical equipment and controls to be protected from unauthorised access. Individual electrical drives to be capable of being isolated and locked off. Electrical motors should be rated as continuous run.
Junction boxes for submersible pumps and float controls shall be above floor level outside the wet-well. All electrical equipment in sumps, wet-wells, inlet channels, inlet chambers, sited below coping level to be explosion proof. Lighting, appropriate to the needs of the end user, to be provided in working areas.
Registration of electrical / motorised equipment with Department of Safety and Health (DOSH).
Emergency stop button / isolator shall be provided for each equipment. Power driven machinery to be guarded.
All equipment to be regularly checked and prominently marked accordingly
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Section 3 Sewage Characteristics and Effluent Discharge Requirements
Sewage Characteristics and Effluent Discharge Requirements
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3.1
Introduction The Environmental Quality Act (EQA) 1974 specifies two standards for effluent discharge: Standard A for discharge upstream of any raw water intake, and Standard B for discharge downstream of any raw water intake. The current Third Schedule of the Environmental Quality Act 1974, under the Environmental Quality (Sewage and Industrial Effluents) Regulations, 1979, regulations 8 (1), 8 (2) and 8 (3) has been revisited and the Department of Environment has proposed 8th Schedule for the Act which stipulate effluent discharge limits for parameters specific to domestic wastewater. The effluent discharge limits in 8th Schedule are summarised in Table 3.2. All sewage treatment plants design shall take into consideration of the 8th Schedule and shall comply with the proposed limits.
3.2
EQA Effluent Standards
3.2.1
Purpose of Effluent Standards Effluent standards are used to regulate the disposal of effluent from STP to any receiving waters. The regulation of such discharges will protect receiving waters and their associated aquatic ecosystems, and will also protect public health from the harmful effects of untreated sewage. The need for these standards has been influenced by the fact that sewage discharges contribute a significant amount of the biodegradable organic matters, suspended solids and ammoniacal nitrogen to the nation’s waterways.
3.2.2
Interpretation of EQA Effluent Standards The EQA effluent standards have the following characteristics: a)
They represent maximum or absolute values which may not be normally exceeded. For this reason, EQA effluent standards are also referred to as absolute standards
b)
Measurement of effluent quality is to be taken using a single grab sample rather than a time averaged composite sample
c)
Generally, effluent standards do not allow the flexibility for them to be compromised through dilution and the assimilative capacity of receiving water.
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3.3
Design Requirements to Achieve EQA Effluent Standards
3.3.1
Purpose of Design Requirements The purpose of design requirements is to ensure that the effluent standards can be met under the normal operations of a sewage treatment plant. The quality of effluent from a STP is expected to vary due to the natural variability in the flows and loads into the plant. Therefore, the design effluent parameter shall be less than the required effluent standards to ensure that, when the plant is under normal operation, any grab sample of effluent will comply with the consent EQA effluent standards.
3.3.2
Design Values Typical composition of untreated domestic sewage is given in Table A.2, while Table 3.1 tabulates the design influent values to be adopted in the design of a treatment plant. Table 3.1 - Design Influent Values Value (g/ capita.day)
Value (mg/l)
Biochemical Oxygen Demand (BOD5)
56
250
Suspended Solids (SS)
68
300
Chemical Oxygen Demand (COD)
113
500
Total Nitrogen (TN)
11
50
Ammoniacal nitrogen (AMN)
7
30
Total Phosphorus (TP)
2
10
Oil and Grease (O&G)
11
50
Parameter
These design values allow for transient reductions in treatment efficiency, due to periodic plant maintenance and unforeseen high impulse of hydraulic and organic loadings on sewage treatment process units. All STP shall be designed to produce final effluents with BOD5, SS, COD, O&G and AMN values less than or equal to the design effluent values. This is to ensure a high degree of consistent compliance with the required effluent standards. The effluent E.Coli compliance is subject to the sensitivity of the receiving watercourse and of the Commission’s directive.
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Table 3.2 - Design Effluent Values Effluent Discharge to Rivers / Stream Parameter
Standard A Absolute Design
BOD5 SS COD AMN Nitrate Nitrogen Total Phosphorus O&G
Standard B Absolute Design
Effluent Discharge to Stagnant Water Bodies* Standard A Standard B Absolute Design Absolute Design
20 50 120 10
10 20 60 5
50 100 200 20
20 40 100 10
20 50 120 5
10 20 60 2
50 100 200 5
20 40 100 2
20
10
50
20
10
5
10
5
N/A
N/A
N/A
N/A
5
2
10
5
5
2
10
5
5
2
10
5
Notes: NA = Not Applicable All values in mg/l unless otherwise stated. * Stagnant Water Bodies refer to enclosed water bodies such as lakes, ponds and slow moving watercourses where dead zone occur.
In cases where treatment plant discharge capacity is higher than the receiving river flow rates, the final effluent quality has to be designed to ensure minimal environmental impact.
3.4
Sewage Pollutants Removal
3.4.1
Biochemical Oxygen Demand (BOD5)
BOD5 is used to measure the biodegradable organic fraction in raw sewage. Based on standard BOD5 measurement, the oxygen demand measured is usually influenced by the following three (3) phenomena: a) b) c)
Oxygen demand by breakdown of soluble carbonaceous matter
Oxygen demand by breakdown of suspended particulate carbonaceous matter Oxygen demand by oxidation of ammonia to nitrate by nitrifying bacteria present in the effluent sample
After undergoing biological treatment in the secondary reactor, residual soluble carbonaceous BOD 5 matter present in the effluent reduces in concentration to below 15 mg/l. Subsequently, nitrifying bacteria populations tend to grow rapidly feeding on ammonia which is present Sewage Treatment Plants
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in the partially treated sewage. Nitrification may not be complete at levels of 5 mg/l of residual soluble carbonaceous biodegradable matter. It depends on whether sufficient oxygen is available for the oxidation of ammonia to nitrate. Hence, all BOD 5 measurements shall adopt nitrification inhibition step to ensure that the carbonaceous oxygen demand is reflected accurately in the overall BOD5 measurement. 3.4.2
Total Suspended Solid (TSS) Sewage contains solid materials that can settle at the bottom and also give impact on the benthic life. They can also appear in suspension solids form that can increase turbidity and affect the light availability for aquatic life. The amount of solids in sewage is usually measured as “total suspended solids” or TSS. The desired solid removal in sewage treatment plants should not exceed the absolute TSS discharge limit of 50mg/l and 100mg/l for Standard A and Standard B, respectively. To ensure effluent consistently complies with Department of Environment’s Effluent Limits, provisions must be made to allow for future incorporation of a flocculator in the clarifier. This will enhance clarification performance. Chemical (polymer) can also be added in flocculation clarifiers to further enhance solids settlement in the clarifiers. Otherwise, a dual media filtration system following conventional secondary clarifiers can also be used to ensure that TSS concentration of 20 mg/l to 40mg/l is consistently achieved.
3.4.3
Chemical Oxygen Demand (COD) COD content reflects the chemically oxidized organic matter. Hence, it includes refractory fractions of organic matter as well as reduced inorganic constituents present in the wastewater. The COD measurement offers quick estimate of carbonaceous material compared to conventional BOD measurement. Additionally, high COD reflects inert reduced inorganic elements and also unbiodegradable organic that comes from industrial contamination. Based on the bi-substrate hypothesis, COD fractions comprising of readily biodegradable, slowly biodegradable and unbiodegradable estimates are adopted in advanced modeling for STP design. Such advanced modeling takes into consideration the treatment process requirements of different COD fractions as it varies in susceptibility to microbial respiration and degradation.
3.4.4
Oil and Grease (O&G) O&G that is detected in domestic sewage refers to the fraction of organic matter that is soluble in organic solvents such as hexane.
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The composition comprise primarily of wax, edible oils and fatty matter of animal or vegetable origins. O&G (mixture of tri, di and mono-glycerides) in its liquid form results in floatable scum formation in treatment systems whilst its solid form causes the clogging of systems. O&G is separated from raw sewage by provision of grease chambers (be it manual or mechanized scum skimmer removal) at primary treatment stage. Removal at the primary stage is essential to prevent interference of oil particles on biological reactions in the secondary treatment. It also prevents undesirable organic load of extremely slow biodegradable constituents into aerobic systems. Such first line oil and grease removal protects against contamination in the treatment plant as well as in the receiving water. 3.4.5
Nitrogenous Compound Removal of nitrogenous compounds needs to be considered in STP design. These compounds found in various forms (ammonia or ammoniacal nitrogen, nitrate nitrogen and nitrite nitrogen) could be detrimental to natural water bodies and potable consumption. Total organic nitrogenous compounds in raw sewage typically comprise of nitrogen in the form of proteins, amino acids and urea along with ammoniacal nitrogen. Ammoniacal nitrogen results from the decomposition of organic nitrogen particularly from hydrolysis of urea. Total Kjedhal Nitrogen (TKN) analysis determines the organic nitrogen and the ammoniacal nitrogen fractions.
3.4.6
There are two main biological processes for removing nitrogenous compounds, namely the assimilation of ammonia nitrogen into the microbial biomass and the nitrification-denitrification process. The latter involves two conversion steps. Firstly, nitrification followed by denitrification by microbial heterotrophs that convert nitrates into nitrogen gas. Nitrification comprises two-step oxidation of ammonia nitrogen into nitrate by nitrifying bacteria. All treatment systems shall provide full nitrification and denitrification in the secondary biological reactors with sufficient air supply to facilitate nitrification. This will ensure that effluent discharge complies with the required discharge limits. Phosphorus Compound The constituents of total phosphorus compounds in raw sewage are organically bound phosphorus and inorganic phosphorus (orthophosphates and polyphosphates).
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Some fractions of the essential phosphorus nutrients from the influent will be assimilated for microbial growth during secondary biological treatment. However, excessive phosphorus nutrient will occur when above the assimilated with stagnant receiving water bodies (e.g. ponds), which will result in nutrient enrichment and produce harmful algae blooms. Hence, the design for sewage treatment plant effluent that discharges into stagnant water bodies should take into considerations the impact of excess phosphorus contamination.
3.5
Sludge Characteristics and Treatment Requirements Sludge treatment and management are as important as the sewage treatment to minimise impacts to the environment. Sludge produced from treatment process is usually in liquid form, which typically contains 0.25 to 4.0% of solids, depending on the type of treatment process being used. It also contains grease, fats, organic and inorganic chemicals. High concentrations of certain components will determine the type of sludge treatment process to be used. Sludge shall be thickened, stabilized, conditioned and dewatered before it is finally disposed off in accordance to requirement stipulated by Department of Environment. The dried sludge must attain a minimum of 20% dry solid content before off-site disposal. Close attention is required when planning and designing sludge treatment processes to ensure bio-solid to be disposed do not contain any harmful substance that will affect the environment. Additionally, stabilization process should be designed to reduce any potential presence of microbial pathogens. Options of ultimate disposal include landfill and land application.
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4.1
Introduction The induced physical, chemical and biological reactions that occur in a sewage treatment plant (STP) lead to waste emissions in the following forms: a) b) c) d) e) f) g)
gases and vapours, some of which contain obnoxious compounds, including bacteria and viruses. noise. odour. vibration. unwanted solid matter. undesirable by-product liquors containing highly concentrated pollutants. heat.
As such, a sewage treatment plant can degrade the amenity of its surroundings, especially in residential areas. Careful consideration of siting is required to minimise nuisance to the public. Sufficient land needs to be set aside during the planning stage to take into account regional treatment plant development and the proper sewerage planning for housing, commercial and institutional developments. This section sets out the important factors and considerations associated with the identification of proper sites to locate sewage treatment plants. Typical workflows in the site for sewage treatment plants are illustrated in Figures 4.1 and 4.2. It also addresses the selection of appropriate treatment concepts and sufficient land area requirements for treatment plants in relation to the effluent standards.
4.2
Treatment Plant Siting
4.2.1
Buffer Zones Suitable buffer distances should separate a sewage treatment plant from its surrounding areas. Buffer Guidelines for the Siting and Zoning of Industries as recommended by the Department of Environment (DOE) should be referred to during the planning of suitable location for treatment plants. The buffer distances recommended in the guidelines depend on the category of industry being considered.
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The provision of buffer zones is essentially an environmental requirement controlled by the relevant planning authority. The agreement of the Local Planning Department on buffer zone and plant siting should be sought at an early stage in the Town and Country planning procedures. The buffer zone requirements for treatment plants to be observed under this Guideline are as follows. Refer to Figures 4.3 and 4.4 in this section for further clarification. a) b) c)
d)
e)
Minimum distance of 30 m from the fence of the treatment plant to the nearest habitable building property line within residential and commercial development. Minimum distance of 20 m from the fence of the treatment plant to the nearest property line within industrial development.
Minimum distance of 10 m from the fence of the treatment plant to the nearest habitable building property line if the proposed treatment plant is fully enclosed. A fully enclosed plant is defined in section 7.3.1. A minimum distance of 10 m from the fence of the treatment plant to the nearest habitable building property line if the proposed treatment plant is covered or buried. However, this reduction in buffer requirement does not apply if the nearby habitable buildings are of high rise type. A covered or buried plant is defined in section 7.4.1.
Plants with PE less than 150 but are provided with proper odour and noise mitigation measure may have a 10 m reduced buffer at the discretion of the Commission.
The buffer zone can be used for any purpose except permanent habitable buildings. For example, the buffer zone maybe used as a drainage reserve, road or highway reserve, transmission reserve, utility reserve or public park. In the case where buffer area is to be regularly used by the residents such as car park and playgrounds, proper precautions during design stage must be taken to minimise nuisance such as odour, noise and unpleasant sight to the surrounding environmental. Adequate and proper screening, odour containment and treatment facilities must be provided at the sewage treatment plant to address these issues.
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4.2.2
Siting Criteria The following criteria shall be observed when siting treatment plants. a) b) c) d) e) f) g)
h)
Plants shall be located as far as possible from habitable building to minimise nuisance to the surrounding.
Plants shall be located at the lowest point of a sewerage catchment basin so that sewage can gravitate into the plant. Plants shall be located near to a suitable watercourse that is able to receive and assimilate treated effluent from the plant without reducing beneficial uses of the water course downstream. Plants shall be located on an area that is relatively flat or with relatively mild slope across the site that would be useful in promoting efficient hydraulics.
The shape of the land area selected shall be such as to minimise the extent of unusable area within the lot. Plants shall not be located in an area that will result in long term operational problems or rapid deterioration of the assets. Plants shall have proper access road leading to it. Plants shall be sited away from the followings: i)
ii)
iii)
Existing cemeteries and gazetted reserves for cemetery. Religious centres.
Eating places.
i)
Plants shall be located such that sewers are easily connected/ conveyed to the proposed site.
j)
If temporary treatment plants are to be provided, they shall be located as near as possible to public trunk sewers.
k)
For safety reasons, plants shall be located away from children playgrounds.
Emergency bypass shall be provided either at the last manhole or wetwell. The bypass shall discharge to the nearest drain which shall have sufficient capacity to cater for the discharge during rainfall. 4.2.3
Environmental Impact Assessment An environmental appraisal or environmental impact assessment (EIA) study shall follow Environmental Quality (Prescribed Activities) (Environmental Impact Assessment) Order, 1987 under Section 34A of the Environmental Quality Act, 1974 (the EIA Order, 1987 and the
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EQA, 1974 respectively). The type and scope of the study will depend on the classification of the plant and the environmental sensitivity of the locality being considered. EIA shall be conducted in compliance with Volume 2 of the MSIG. 4.2.4
Hazard and Operability Studies Hazards and Operability (HAZOP) study shall be conducted in compliance with Volume 2 of the MSIG. The type and scope of the study will depend on the classification of the plant.
4.3
Treatment Plant Sizing
4.3.1
Modular Units Stage development of a STP is governed to a large extend by the timeframe of the overall development plan of the catchments and the size, shape and soil condition of the land reserved for the STP. Modular units will be constructed to cater for the stage development. In determining the appropriate number of modules and corresponding timing for a staged development, it is crucial for the designer to estimate the flow capacity build-up over the entire development phases. The modules must have sufficient capacity to treat the sewage to meet the efficient discharge standard, without compromising the economical viability of operation and maintenance. Too many modules and unit processes will definitely increase equipment maintenance. On the other hand, inadequate modules will result in an inefficient treatment performance due to insufficient capacity and flexibility during the early stage. Table 4.1 Modularisation Requirements STP Classifications
No. of Modules
No. of Trains
Class 1 (<1,000PE)
1
N/a
Class 3 (5,001PE – 20,000PE)
Min. 2, Max. 3
Class 2 (1,001PE – 5000PE)
Class 4 (>20,000PE)
1
Min. 4, Max. 10
Max 2
Max 2 for each Module Max 2 for each Module
Table 4.1 indicates the modularisation requirements in accordance to sewage treatment plant classes to attain an efficient modularisation of sewage treatment plant development. Each module shall be of equal size
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and of similar treatment process. If the proposed process is different from the original system, special approval is required from the Commission. Certain unit processes are subject to the modularisation requirements in Table 4.1 while other unit processes are designed for the ultimate phase during the first stage of the development. An example of this is the headworks of a STP designed for the ultimate phase while the secondary processes are added progressively as the future phases come on-line. Modular treatment plants that are designed with two (2) or more parallel streams must be provided with pipeworks and valves to isolate each stream of unit process during maintenance and major shut down without interfering normal operation of the remaining stream. 4.3.2
Standby Units To avoid significant down time in sewage treatment and overloading of the process units, standby units shall be provided for the following processes: a)
Inlet Works/Pumps
c)
Grit Chambers
b) d) e) f)
Screen Facilities
Biological Treatment Secondary Clarifiers Sludge Facilities
The common standby mechanical equipments are as follows:a)
Pumps (raw sewage, effluent, sludge, etc)
c)
Blowers
b) d)
Mechanical screens
Any other mechanical equipment
Detailed requirements of standby units shall follow the requirements in Section 5. 4.3.3
Back-up Capacity The back-up capacity provided shall be such that when one unit process is taken out of operation, the remaining units shall not be overloaded beyond 50% of their rated capacities.
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4.3.4
Design Flow
It is recommended that unit processes that are designed on average flow basis are sized to allow for infiltration in accordance with MS 1228. Conveyance networks shall be sized to cater for peak flows, except for those networks located downstream of an equalisation tank. All unit processes shall be designed based on the maximum ultimate design flow.
4.4
Land Area Requirements
The recommended land area requirements for various sewage treatment plants capacities are derived from relevant treatment process concepts and also taken into consideration other design criteria.
The land area requirements and buffer allowance for temporary sewage treatment plants maybe reduced at the discretion of the Commission on a case by case basis.
4.4.1
Class 1 and 2 Plants
The recommended land area requirements for Class 1 and 2 plants (up to 5000 PE) are given in Table 4.2 and Table 4.3 respectively. The net area does not include the 30 m buffer zone surrounding the plant, but does include appropriate set backs and access paths within the plant. The area requirements given are sufficient to achieve an effluent conforming to Standard A discharge requirements. It is important that allowance is made for sufficient buffers in planning approvals, to avoid future complaints in relation to the siting of the plant.
4.4.2
Mechanised Class 3 to 4 Plants
For Class 3 and 4 plants with mechanised systems, the recommended land area requirements are given in Table 4.4 and 4.5. These systems are to be used in normal developed and urbanised areas. The net area does not include the 30 m buffer zone surrounding the plant, but does include appropriate set backs and access paths within the plant. The area requirements given are sufficient to achieve an effluent conforming to Standard A discharge requirements. It is important that allowance is made for sufficient buffers in planning approvals, to avoid future complaints in relation to the siting of the plant.
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4.4.3
Aerated Lagoons and Stabilisation Ponds
For aerated lagoon and stabilisation pond treatment systems, the recommended land area is as shown in Table 4.6. Sufficient buffer areas shall be allowed for surrounding the plant as per paragraph 4.2.1.
4.4.4
Imperfect Sites
The recommended land area requirements represent an ideal case, where it is possible to locate the STP within a rectangular land area that is relatively flat. In practice, the allocated land may be irregular in shape, sited in low lying or undulating to steep valley terrain. For such cases, suitable adjustments to the land area requirement have to be made.
Thus, the shape and elevations of the land allocated for the STP development must be determined during planning stage so that the configuration of the STP can be planned properly in order to allocate adequate land for the purpose. This also enables estimates for additional land required. It may also be required to cut or fill operations to level the land.
4.4.5
Reduced Land Areas for STPs
The area requirements, as stipulated in Table 4.2, 4.3, 4.4, 4.5 and 4.6, must be adhered to as strictly as possible. The required areas in these tables include appropriate setbacks and access paths within the plant. However the areas have not include any buffer zone surrounding each plant as indicated in Section 4.2.1.
In developments where land is really a constraint the Commission may consider for a reduced land area requirement. The project proponent will have to demonstrate clearly the need for a reduced land area before an approval can be granted. For this case, detailed design calculations of all unit processes, together with the proposed layout, shall be submitted at the planning stage for consideration of approval by the Commission. Otherwise, the land area required under these guidelines must be followed.
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Table 4.2 Land Area Requirements for Class 1
Population Equivalent
Land Area Requirement * (acre) (m2)
100
210
0.052
150
285
0.070
200
360
0.089
250
430
0.106
300
485
0.120
350
545
0.135
400
600
0.148
450
655
0.162
500
700
0.173
550
745
0.184
600
790
0.195
650
835
0.206
700
870
0.215
750
905
0.224
800
940
0.232
850
980
0.242
900
1010
0.250
950
040
0.257
1000
1070
0.264
Note: * The required area only includes appropriate setbacks and access paths within the plant but not the buffer zone surrounding each plant as indicated in Section 4.2.1.
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Table 4.3 Land Area Requirement for Class 2 Population Equivalent
1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 3000 4000 5000
Land Area Requirement * (m2)
1115 1160 1200 1240 1275 1310 1340 1370 1395 1420 2226 2671 3076
(acre)
0.276 0.287 0.297 0.306 0.315 0.324 0.331 0.339 0.345 0.351 0.55 0.66 0.76
Table 4.4 Land Area Requirements for Mechanised Class 3 Plants Population Equivalent
Land Area Requirement * (ha)
(acre)
5001
0.31
0.76
6000
0.40
0.99
7000
0.49
1.21
8000
0.59
1.46
9000
0.69
1.71
10 000
0.78
1.93
15 000
1.00
2.47
20 000
1.19
2.95
Note: * The required area only includes appropriate setbacks and access paths within the plant but not the buffer zone surrounding each plant as indicated in Section 4.2.1. Sewage Treatment Plants
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Table 4.5 Land Area Requirements for Mechanised Class 4 Plants Population Equivalent
20 001 25 000 30 000 35 000 40 000 45 000 50 000 55 000 60 000 65 000 70 000 75 000 80 000 85 000 90 000 95 000 100 000 110 000 120 000 130 000 140 000 150 000 160 000 170 000 180 000 190 000 200 000 250 000 300 000 450 000
Land Area Requirement * (ha) (acre)
1.19 1.37 1.53 1.81 1.97 2.12 2.23 2.37 2.52 2.67 2.93 3.27 3.49 3.69 3.89 4.07 4.25 4.57 4.87 5.14 5.39 5.63 5.84 6.05 6.25 6.43 6.60 7.36 7.98 9.36
2.95 3.38 3.79 4.48 4.88 5.25 5.52 5.84 6.22 6.61 7.23 8.07 8.61 9.12 9.61 10.06 10.49 11.29 12.02 12.70 13.32 13.90 14.44 14.95 15.43 15.89 16.32 18.20 19.73 23.14
Note: * The required area only includes appropriate setbacks and access paths within the plant but not the buffer zone surrounding each plant as indicated in Section 4.2.1.
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Table 4.6 Required Land Area for Stabilisation Pond and Aerated Lagoons Population Equivalent
Standard A*
Standard B*
(ha)
(acre)
(ha)
(acre)
2000
0.48
1.18
0.45
1.10
4000
0.89
2.20
0.71
1.75
3000
5000
10 000 15 000 20 000 25 000 30 000 35 000 40 000 45 000 50 000 55 000
0.69
1.09 2.03 2.92 3.78 4.62
2.68 5.01 7.2 9.3
11.4
5.45
13.5
7.05
17.4
6.26 7.85 8.63 9.40
60 000
10.16
70 000
11.68
65 000
1.69
10.92
15.5 19.4 21.3 23.2
0.59
0.82 1.31 1.72 2.09 2.42 2.74 3.04 3.32 3.59 3.86
2.04 3.24 4.25 5.16 5.99 6.77 7.50 8.2 8.9 9.5
4.11
10.2
4.60
11.4
25.1
4.36
28.9
4.83
27.0
1.45
10.8 11.9
75 000
12.42
30.7
5.06
12.5
85 000
13.91
34.4
5.50
13.6
80 000 90 000 95 000
100 000
13.17 14.64 15.37 16.10
110 000
17.54
130 000
20.38
120 000
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32.5 36.2 30.0
39.8
43.3
46.9 50.4
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5.28 5.72 5.93
6.13
6.54
6.93
7.31
13.1 14.1 14.6
15.2
16.2
17.1
18.1
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Table 4.6 Required Land Area for Stabilisation Pond and Aerated Lagoons (Continued) Population Equivalent
140 000
150 000
160 000
170 000
180 000
190 000
200 000
Standard A*
Standard B*
(ha)
(acre)
(ha)
(acre)
21.79
53.8
7.69
19.0
24.57
60.7
8.40
20.8
27.32
67.5
23.18
25.95
28.68
30.04
57.3
8.05
19.9
64.1
8.75
21.6
70.9
9.43
23.3
74.2
9.09
9.76
22.5
24.1
Note: * The required area only includes appropriate setbacks and access paths within the plant but not the buffer zone surrounding each plant as indicated in Section 4.2.1.
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Figure 4.1 STP Land Area Requirements for Planning Layout Approval for New Development
Start
Determine catchment served
Determine ultimate PE
Identified effluent requirement
Apply sitting criteria
Is development > 2000 PE?
Is development in urban area?
Y
N
Use land area from Table 4.2 (Class 1 plants)
N
Use land area from Table 4.3,4 and 5 (Class 2 to 4 plants)
Use land area from Table 4.6 (pond systems)
End
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Figure 4.2 STP Land Area Requirements for Structure Plans Figure 4.2 – STP Land Area Requi
rements for Structure Plans
Start
Local plan Plan formulation Formulation
Perform the next two steps concurrently Determine natural drainage catchments
Determine suitable receiving waters
Calculate ultimate catchment PE
Identify effluent standards Look up land area requirements in Tables 4.2, 4.3, 4.4 or 4.5
Table 4.2: Up to 1000 1,000PE PE
Table 4.3, 4 and 5: Greater than1000 than1,000PE PE for urban areas
Table 4.5: For remote area siting of STP
Apply siting criteria
Select and zone suitable site
Consider multi-use of buffer areas
Reserve land for STP
End
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Requirements for Physical Design Requirements for Physical Design
Figure 4.3 Guidelines For Buffer Zone Figure 4.3 Guidelines For Buffer Zone Plants Situated In Residential / Commercial Areas Treatment Plant Site
Buffer Zone 30m Min.
Residential / Commercial Plot
5m Min. Access And Screening
Property Boundary
STW Fence
Open Treatment Plant
Beautification Zone
Treatment Plant Site
Buffer Zone 10m Min.
Residential / Commercial Plot
5m Min. Access and Screening
Enclosed Plant
Property Boundary
STW Fence
Treatment Plant Site
Buffer Zone 10m Min.
Residential / Commercial Plot
5m Min. Access And Screening Property Boundry
STW Fence
Buried / Covered Plant
Buffer Zone 30m Min.
Treatment Plant Site
Residential / High Rise
5m Min. Access and Screening
Enclosed Plant
Property Boundary
STW Fence
Plants Situated In Industrial Areas Treatment Plant Site
Buffer Zone 20m Min.
Industrial Plot
5m Min. Access And Screening Open Treatment Plant
Factory Fence
STW Fence
Note : The buffer area can be used for roads, drains, utility reserve, agricultural or other similar purposes.
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30m Surround For Residential and Commercial Development 20m Surround For Industrial Development 10m Surround For Fully - Enclosed Plants
10 m
20 m
30 m
STP LAND AREA REQUIREMENT
The land shall be relatively flat and of a regular shape. Any unusable area within the plot shall be minimised.
Note: Buffer areas can be used for roads, drains, utility reserve, public parks, agricultural or similiar purposes other than permanent habitable buildings.
10 m
20 m
30 m
Requirements for Physical Design Requirements for Physical Design
Figure PlanView View of of Buffer Figure 4.44.4- Plan BufferZone ZoneRequirements Requirements
Malaysian Sewerage Industry Guidelines Malaysian Sewerage Industry Guidelines
Requirements for Physical Design
4.5
Mechanical and Electrical Requirements Some general guidelines on the design and installation of mechanical and electrical equipment are outlined below.
4.5.1
Mechanical Installation I)
Design Considerations
The designer shall consider incorporating the following criteria: a) b) c)
The design shall simplify the equipment required, control system, maintenance and operational procedures, while fulfilling the intended performance and standard of service.
The brand and models of major drive equipment (e.g.: pumps, blowers, aerators, clarifier scrappers, etc.) shall be those approved by the Commission.
The types and makes of equipment provided throughout the facility shall be standardised, whenever possible.
d) Only new and genuine equipment shall be provided. e) f)
g) h) i)
II) a) b) c)
Equipment sizing and selection shall minimise energy and other consumables costs. The minimum economic life of equipment.
Material selection shall be in accordance with the Commission specifications or/and other relevant international standards. Components shall be robust and suitable for use. Where thin metal sheeting is used, it shall be stiffened to minimise distortion.
Water storage tanks shall not be placed on the roof top of any control room; all water supply system shall be homed with separate entrance. Installation The base frame of rotational equipment or any equipment that may induce vibration shall be provided with anti-vibration mount. All moving parts shall be designed and installed in a manner that is inherently safe to operate.
Foundations shall be adequately designed to include all dynamic load and anchored to withstand all loads imposed by the equipment. Reinforced concrete foundations are preferred.
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d)
Equipment shall be accurately located, levelled and secured by holding down bolts. Non-shrink grout shall then be used to complete the foundation. In some cases, a resilient connection to the foundation is required, in which case, the manufacturers instructions shall be followed.
e) Holding down bolts shall be of stainless steel and shall be of a minimum grade 316 if in contact with sewage. f)
g) h)
Puddle collar is required for all pipe passing through all walls.
Appropriate joints shall be provided in all pipeworks to facilitate the removal of equipment, meters, valves and other special items without dismantling the entire pipeline. Valves shall be provided for isolation purpose.
i) Outdoor and dry installation pump shall be provided with housing. j)
k)
4.5.2
The designer must ensure that the unit processes are arranged in such a way to prevent/reduce criss-crossing of piping works, unnecessary bends, choking of interconnected pipe and excessive hydraulic losses through the system.
The platform level of mechanical equipment and controllers of any process unit shall be located above design flood level.
Vibration All revolving parts shall be properly balanced both statically and dynamically so that in running up to, at full normal operating speeds, and at any loads up to the maximum there shall be no undue vibration anywhere in the machine or transmitted to the adjacent structure. The criteria adopted for vibration severity shall be the RMS value of the vibration velocity in millimeters per second. The bare frame of rotational equipment or any equipment that may induce vibration shall be provided with anti-vibration mount. Where rotational equipment or equipment which may induce vibration is connected to piping, then vibration isolator shall be provided.
4.5.3
Noise Noise levels from machinery shall comply with the Factories and Machinery (Noise Exposure) Regulations 1989 and Occupational Health and Safety Act. Noise control measures and appropriate safety protection for operators must be provided where necessary.
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Noise control measures shall be implemented to control the generated noise level to below 65 dB at a distance of 2 m from the boundary of the housed noise source at all times. Additionally, the general noise levels generated shall be measured 10 m from any point of the plant site within the nearest public space and/or occupied space to an acceptable level stipulated by the appropriate regulators. Silencers and acoustic enclosures shall be provided as required to achieve the above noise level reduction. Enclosures used to achieve these noise reductions shall permit ready access to the equipment for routine maintenance. Adequate air ventilation shall be provided to allow cooling of the enclosure to prevent overheating of the equipment/motors. Noise level measurement shall be made with a sound level meter which complies with BS EN 60651 and which is fitted with an ‘A’ weighting network. The sound pressure level shall be measured in dB (A). Noise level for all electronically operated electrical device such as soft starters, variable speed drives and others shall be conform to IEC, EN. Thus it shall fulfil all EMC Immunity requirements complying with EN500082-1, EN50082-2, EN50082-3. 4.5.4
Safety Around Equipment All designs and equipment shall be made and installed with safety in mind. Nothing in this Design Guidelines shall remove the designer’s obligation to incorporate equipment or designs that would increase the safety of the plant. The installation layout and equipment design shall not allow any item of equipment to be so positioned that danger could arise to operating personnel and equipment during normal operation and maintenance. Particular attention shall be paid to the positioning of switch board, control panel, cables, switch gears, lighting, small power, rotational equipment, other electrical equipment and accessories. All facilities shall be designed to comply with the Occupational Safety and Health Act 514, 1994; properly designed treatment plants will enable the operator to safely handle the treatment plant throughout its design life. The plant shall also be designed to comply with other related Acts such as IEE, Akta Bekalan Elektrik 1990 (Akta 448) and Peraturan-Peraturan Elektrik 1994. Safety level for all electronically operated electrical device such as soft starters, variable speed drive and others shall conform to IEC, EN, UL, NFC and VDE. Thus it shall fulfill EN 50178, EN 60204-1, EN 60950 (2000, 3rd edition), IEC 61800-5. Where appropriate, IEE and Akta 448 (1990) and Peraturan Elektrik 1994 must be complied within all electrical installation.
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The following shall be provided: a)
b)
c)
d) e)
f)
g) h)
All moving parts shall be protected by suitable guards. Where inspection is required, an open mesh with frame and suitably supported maybe used. The maximum aperture of the mesh shall be 6 mm.
All guards shall be readily removable and replaceable to they correct orientation only. However the guard shall be designed with features to prevent accidental dislocation from its’ original position. The fasteners when dropped during dismantling, must be easily retrievable and should not damage any equipment or endanger personnel, else fixed fasteners shall be used. An emergency stop button, preferably of mushroom head type shall be located adjacent to all equipment. More than one emergency stop button shall be used, if access around the item is restricted.
Long items, such as conveyor belts, shall have an emergency lanyard applied to each accessible length of conveyor. Surfaces which are greater than 50°C shall be guarded.
Permanent warning signs shall be posted at visible location at all dangerous areas and shall clearly indicate the nature of risk at that area. This includes warning signage at digesters area, high tension room, low voltage room, generator room and other hazardous areas. Clear working space as recommended in Figure 4.5 shall be provided. Automatic CO2 discharge triggered by heat and smoke sensors shall be installed in high voltage switch room, transformer room, low voltage switch room and generator room.
i) High tension room shall have signage to clearly indicate the purpose of the room and also safety signage to prevent unauthorised entry.
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Figure 4.5 - Clear Working Space 1 m or 1.5 W or whichever greater
Wall
Equipment
Wall
1 m or 1.5 W or whichever greater
W
Equipment L
4.5.5
1 m or 1.5 W or whichever greater
Motors, Controllers and Motor Starters I) a) b) c)
Motors Provide readily replaceable anti-condensation heaters for motors that do not require frequent operation. At least three thermistors to be provided for motors which are >50 kW. Electrical motors should be rated as continuous run.
d)
Motors > 22kW shall be protected with soft starter or variable speed drive.
e)
Where water hammer prevails, frequency inverter shall be provided.
f)
II) a)
b)
The appropriate cooling system based on the requirements of the equipment shall be provided. Controllers Start push buttons to be green and recessed Stop push buttons to be red and recessed
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c)
Emergency stop push button to be red and mushroom head type
d) ON signal lamps to be green e) OFF signal lamps to be red f)
III)
Trip signal lamps to be amber
Motor Starters
a) Up to 3.7 kW – Direct-On-Line starters b)
Above 3.7 and up to 7.5 kW – Star/Delta starters
d)
More than 22 kW – Soft starter
c) e)
Above 7.5 and up to 22 kW – Auto-transformer starters Above 50 kW – Variable speed drive is preferred
Soft starting of motors above 30kW or greater in size is necessary to minimise power disturbances (e.g. power surge) and process disturbances (e.g. water hammer). Variable speed drive shall be considered at application where variable capacity maybe need to enhance the process flexibility, for example, aeration device and blowers. 4.5.6
Power Supply Systems Power supply to sewage treatment plants shall be as follows:
Category
Supply Requirements
Sewage Treatment Plant
A
Single incomer with properly design control All Class 1, 2 and 3 overflow system during power failure (all STPs electrical control system shall be located above design flood level)
B
B1) Single incomer with diesel generators for back-up supply.
STP Class 4
B2) Single incomer with control overflow system and genset contribution fee. a)
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Where a SCADA system is provided and essential parameters are to be monitored during power supply interruptions, a DC supply or a UPS (uninterrupted power supply) must be provided. Volume 4
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b)
Batteries/UPS shall have the capacity to operate the SCADA system for a minimum 6 hrs during power failure to safe last event, to monitor the essential parameters and to enable early warning system.
c) No direct tapping of power is allowed from distribution board (DB). Proper protection shall be provided for any direct connection from switchboard. Earth leakage current breaker (ELCB) shall be provided for DB. d)
e)
f)
g)
h) i) j)
4.5.7
The power system distribution shall be designed to achieve a minimum power factor of 0.9. For phase development, the plant and power system distribution shall be designed for maximum load and installed in appropriate modular unit to ensure that the minimum power factor is achievable at all phases of operation.
Equipment shall be protected by either moulded case circuit breaker (MCCB) or miniature circuit breaker (MCB) based on its suitability. Electrical design calculations shall be provided to justify each selection. Every control circuit shall be protected with separate MCB.
TNB meter panels shall be installed close to the site entrance or adjacent to but physically separated from the main switchboard. Suitable flexible steel conduit with approved adaptors shall be supplied and fitted between the main switchboard.
All metering panel shall be located flush with the fence and door opening from outside to enable TNB inspector to read the kWh and kVAhr reading. Provide earthing connected with Current Transformer (CT) for Large Power Consumer (LPC) (i.e. consumption with more than 100A or 10kW).
To provide earthing connected to ELCB/RCCB/ELR or Over Current & Earth Fault relay to protect overcurrent and surge current to all wiring connected to TNB metering panel for Large Power Customer (LPC) or Ordinary Power Customer (OPC). Test for earthing system shall be below or equal 1 Ohm.
Back-up Generator a)
b)
If diesel generators are to be provided they shall be used for essential loads only (these include influent pumping in pump station, feeding pumps in balancing tank, decanter for SBR; minimum 30% aeration requirement; emergency services system, essential lighting and ventilation system. Where generators are installed, they must be accompanied with the necessary supporting systems, including automatic cut-in
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c) d)
e) 4.5.8
in the event of mains failure, fuel storage and transfer; and if installed indoors, including ventilation, fire detection/protection and working alarms.
In the event of power interruption/failure; when diesel generators are used, the SCADA shall be powered by UPS or DC battery. For plants ≥ 100 000 PE, the capacity of the back-up generator may vary provided detail calculation must be provided to justify that sewage can be kept in aerobic condition for a maximum duration of 6 hours Gen-set shall be sized to the incoming TNB voltage requirement.
Switchgear and Control Gear Assemblies a) b) c)
For simplicity, separate the Supply Authority Metering from the main switchboard Electro galvanised plates to be used to protect materials against corrosion due to high humidity Panel isolators and door locks to be capable of padlocking open with 6 mmc - hasp padlock
d) Use separate panel boards for general purpose light and power e) f) g) h) i)
4.5.9
Cabinets are to be constructed to prevent the ingress of insects and vermin
For incomer above 400 A, provide over current and earth fault protection on all starter circuits in excess of 200 A Where a circuit has a main and standby supply, provide an isolator in each supply circuit
Junction boxes for submersible pumps and float controls shall be above the floor or any possibility of flood level and must not be located in the wet well.
Control Cabinets (I) a) b)
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Group all motor starting equipment for an area into multi-motor, starter control board
General Provide 900 mm minimum clearance between an open door and any fixed object.
Provide 900 mm clearance between open cabinet doors of facing cabinets.
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c) d) e) f)
g)
Front access cubicles to have the electrical clearance distances between door mounted equipment and gear tray mounted equipment as specified in the regulations. Mount all equipment inside cabinets on gear trays.
All cabinets to have a base frame, at least 50 mm high.
All control panels shall be provided with phase sequence relay.
All control rooms shall be isolated from invasive environment of the sewerage system, where carbonisation, corrosion or condensation may occurs that lead to short-circuiting.
h) Height to be no greater than 1600 mm internally. i) j) k) l)
m)
Mount cabinet on reinforced concrete plinth, 200 mm minimum above ground. Provide a reinforced concrete paved area for the full width of the cabinet and extending 1 m in front of the cabinet doors, when they are opened. Cable entry from the top only.
Provide forced ventilation fan for cubicles housing PLC equipment. Provide ventilation for variable speed drives and soft starters.
n) Natural ventilation is suitable for direct-on-line, star-delta and auto transformer starters. o)
(II) a) b) c)
d) e) f) g)
The minimum acceptable IP rating and tests required shall be clearly specified.
Outdoor Cabinets Self contained, free-standing, weatherproof cabinets to be constructed of marine grade aluminium, stainless steel grade 316 or glass reinforced plastic. Mount control indication and alarm facilities on internal doors enclosing compartments housing electrical plant and equipment. Provide external doors with security locking facilities.
Provide double roofs on cabinets to reduce solar effects.
Wall mounted outdoor weather proof control panel shall come with an awning extended by at least 2 m from the wall. Floor mounted outdoor weather proof control panel shall come with a roof extended 2 m from the panel.
External weather proof control panel of equal and more than 100 A shall be provided with permanent CO2 fire extinguisher.
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4.5.10
Control Requirements This section outlines the general philosophy on control requirements for the whole facilities.
NO.
TYPE OF PLANT
EWS + PC (monitoring) / Data Logger
SCADA
1.
Network Pumping Station (NPS)
< 100 000 PE
≥ 100 000 PE
2a.
Sewage Treatment Plant
Class 3 STPs
Class 4 STPs
2b.
Sewage Treatment Plant requires full automation, e.g. sequencing batch reactor.
Class 1, 2 and 3
Class 4 STPs
2c.
Sewage Treatment Plant (Standard A)
Class 1, 2 and 3
Class 4 STPs
Notes : EWS – Early Warning System
I) a) b) c)
d) e) f)
g) h) i)
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SCADA – Supervisory Control and Data Acquisition
General Considerations PLC shall restart automatically once the power supply reinstate after a power supply interruption. PLC shall be equipped with manual over-ride features.
Continuously running drives shall restart automatically after a power supply interruption. Plant to have time delayed restarting sequences for equipment to avoid overloading power supply.
Transducers shall be used to sense the signal for related warning alarms. Trip and shutdown to be measured by separate relays.
The operating status and condition of the process shall be verified by measuring appropriate performance indicator and not by inference. SCADA room shall be air-conditioned.
Telephone line must be laid during construction for all sewerage works to be equipped with SCADA.
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II) a)
b) III) a)
Manual Control Interlocks shall be provided to prevent damage to the equipment during equipment start up, for example, bearing overload, overheated, temperature, loss of cooling water, no flow when operating. Selector switches to be provided at one location so that an equipment can be manually operated from that location. Drive Systems Each drive must be independently provided with the following features :
i. ON ii. OFF iii. AUTO
- - -
starts and runs the drive stops the drive operates the drive in accordance with automatic control system
b)
Indicate operation by an ammeter
d)
Local annunciation on motor starter of each fault condition.
c)
e)
IV) a) b) c) d) e)
Record running hours with a local indicator and by computation in a central SCADA system where applicable. Record kilo-Watt.hour (kWh) of major drive equipment. Automatic System Control Facilities Displays operator adjustable parameters, examples set point of top water level in a tank and the target dissolved oxygen level for a process. Ability for the authorised operator to adjust the set point of operator adjustable parameters. A “default” value should always be provided.
Displays to advise operator of the set points of non-operator adjustable parameters. Examples would include the overflow level on a tank and the trip temperature for a bearing. Displays measured values by all instruments, used to measure flow, level, DO, pH, temperature or applicable parameters.
The process control sequences must ensure system problems such as water hammer overtorque or overpressure the equipment of air compressors. Time delayed in starting and stopping of equipment where multiple duty units are installed, use a value with slower rate the final stage of closing, vary the speed of equipment during starting and stopping are some of the option for consideration in careful process automation.
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4.5.11
Supervisory Control and Data Acquisition Systems (SCADA) SCADA is the acronym for Supervisory Control and Data Acquisition. The term refers to a large-scale, distributed measurement (and control) system. SCADA systems are used to monitor or/and to control chemical, physical or transport processes. The following briefly describe the requirements of SCADA while the detail requirements of SCADA are listed in Appendix C. The term SCADA usually refers to a central system that monitors and controls a complete site. The bulk of the site control is actually performed automatically by a Programmable Logic Controller (PLC). Host control functions are almost always restricted to basic site override or supervisory level capability. Provision of SCADA system shall be in accordance with Section 4.5.10. I)
Control Systems
a) b)
All equipment shall be tagged in the SCADA system. Develop sequential function diagrams to specify the control logic to suit the process operation for each system. c) Check the process operation against the resulting sequential function diagram. d) PLC programs to be written in modular form to aid fault finding and commissioning. e) Design programs to be ‘fail to safety’. That is, PLC failure will cause plant to stop. f) On restoration of supply, all controlled system shall be returned to the ready position before automatic restart takes place. g) Bench test all application programs for PLC, before program installation on site. h) Conduct functional control circuits tests for all items of equipment. i) Ensure PLC programming software licences are delivered. j) Provide paper copy listing of all PLC application programs and soft copies of application program (two copies of each required). k) Despite the PE, all plants which requires automation and control shall be provided with human machine interface (HMI) at site. II) a)
Supervisory Systems Where supervisory systems are used, schedule all graphic displays required to control plant using columns to define:
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ii)
iii)
Information displayed Control features
b) Update times for screens to be not more than one second.
c) Nominate the alarm title to be used/displayed for each processgenerated fault input or fault generated internally by the PLC program.
d) Nominate critical and non-critical alarms and the method of differentiation. Examples would be: nominating an alarm on a limit which has been reached as critical and an alarm on a limit which is being approached as non-critical; differentiated by, for example, red/amber lights or horn/bell). e)
f)
At least eight variables to be displayed on a trend graph simultaneously for ease of monitoring and comparison. This is a measure of the level of software sophistication which should be expected. Supervisory system to log running hours for all plant items.
g) Nominate the reports to be generated for plant operation, management and history. For example, reports to be daily, weekly and monthly and the list of parameters to be reported on in each. h)
Alarm analysis, that is, frequency of occurrence, similar plant faults, etc, to be provided as part of the supervising programs.
4.5.12
Early Warning System (EWS)
The EWS is used to monitor the status of the equipment operating inside the treatment plants such as pumps and aeration equipment. It shall act as the means to communicate information via Short Messaging Service (SMS), e-mail or via other telecommunication mean to technical staff for the fast recovery of the treatment system.
EWS system shall be able to transmit digital and analog values from the remote module to the operator through their inputs (equipment) via SMS and e-mail messages in text mode. The modules shall be able to interpret SMS message from the operator to activate or deactivate long distance machine (remote control).
4.5.13
Instrumentation
Provision for instrumentation shall be in accordance with the following Table 4.7. Instruments shall be installed in such a way that they can be removed for maintenance without interrupting the process.
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Table 4.7 Required Process Instrumentation Treatment Unit
Inlet Pump Station
Aeration Blower Decanter Effluent
Sludge (WAS/RAS) Electrical Drive Disinfection Polymer Sludge Feed
Instrumentation
STP Class
Level/ Pressure Flow Measurement Gas Detector (H2S, CO2, O2 & Combustible gases)
All All 4
Air flow/ pressure/ temperature/ rpm
All
Flow Measurement
All
DO/pH/ Turbidity Temperature
4 4
Position Indicator /Speed
All
Flow Measurement
4
Am/Volt/HR/kW/Power Factor meter
All
Dosage/ Level Indicator/ Flowrate
All
Dosage/Transmittance / Flowrate/outlet water level indicator
All
Flowrate/ Pressure
All
For STP with PE 10 000 and above, a digital power meter is required to be installed at all individual panel of major equipment such as raw sewage pump, air blower, aerators, mechanical dewatering unit etc. The digital power meter shall be able to monitor the following: Real-Time Readings
Current, Voltage, Real Power, Reactive Power, Apparent Power, THD (V and I)
Energy Readings
Accumulated Energy (Real kWh, Reactive kVarh, Apparent KVAh)
Demand and peak Readings
Current, Real Power, Reactive Power, Apparent Power
Other:
Power Factor, Load Operating Time
All parameters measured as mentioned must be retrievable at all time.
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4.5.14
Cables and Cabling Installation I) a)
b) c) d) e) f) g) II)
General Segregate cables into the following categories: i)
power (less than 1000 V phase to phase)
ii)
instrumentation/telemetry
iii)
control
Wherever possible, use a separate cable-support system for each cable category.
Separate such cable support systems by minimum clear distances of 300 mm. When one cable support system has to be used, separate cable categories by minimum clear distances of 150 mm.
Secure cable at 900 mm intervals for horizontal runs and 300 mm for vertical runs. Cable ties shall be made of non-corrosive material and if exposed to the environment, shall have UV protection. All cables shall be at least of double PVC protection, and if exposed to the environment then armoured cable shall be provided. Instrumentation
a) Use separate cables for digital and analog signals. b) Marshal cables in a process or geographical area into junction boxes. c) Use multipair cables between areas. III) a) b) IV) a)
Buried Cables Install cables without trees or through joints, unless approved. All buried cables shall be laid in ducts. Underground Ducts Construct road crossings from uPVC conduit of minimum 100 mm diameter with 900 mm cover and encased on all sides with 150 mm concrete.
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b) c)
All other ducts to be PVC conduit laid with a minimum cover of 600 mm. Ducts to be bedded in 75 mm sieved sand. Provide draw strings in all ducts.
d)
Provide cable pits to suit cabling layout and to allow drain-in of cables through the duct work. Cable pits shall be provided no greater than 100 m apart. They shall be fitted with trafficable cast iron covers and equipped with drainage.
e)
Seal ducts into buildings with approved systems providing a fire rating of 30 minutes.
(V) a) b)
Conduits All cabling within buildings or structures where cable trays are not permitted, and in all external locations, shall be installed within conduits. Conduits installed externally shall be arranged to minimise their length and exposure. PVC heavy duty conduit is permissible, where it is protected from physical damage and UV. Otherwise, metal or flexible conduits shall be used.
c) Use flexible steel reinforced conduit for connections, where relative movement and removal for maintenance has to be considered. VI) a) b)
4.5.15
Cable Support Systems Ensure cable support systems in electrical switch rooms, equipment (for example, pump) rooms and service galleries.
When run in common service galleries, ensure cables are not adjacent to hot services.
Earthing and Lightning Protection a)
Provide earthing and lightning protection to meet local regulations.
b) Use a specialist inspector to verify the installation. c)
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Earthing test results shall be submitted and results shall be below or equal to 1 ohm.
d)
Lightning arrestor test results shall be submitted and results shall not more than 5 ohms.
e)
Earthing and lightning arrestor chamber shall be of pre-cast material. Volume 4
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4.5.16
General Purpose Power Provide general purpose power socket outlets as follows: a) b) c) d)
4.5.17
Single phase outlet rated at 10 A adjacent to, or inside each control cabinet and within 10 m of all equipment installations. Three phase outlet rated at 50 A within 20 m of every screen, sludge scraper, clarifier rake, grit collector and conveyor.
Three (3) phase (with neutral) outlet rated at 50 Amp shall be provided at an interval of at least 20 m.
These outlets shall be water proofed industrial type switch socket outlets (SSO).
Manuals, Drawings and Labelling a) b) c)
d)
Provide equipment manuals that are specific to the plant and instrumentation supplied.
System manuals describe the way each system manages the individual items of plant. Ensure these are available in draft form, before testing and commissioning commences.
Provide plant function diagrams, electrical system, electrical circuit, Process and Instrumentation Diagram(P&ID), instrument loop diagrams, electrical design calculations and single line diagrams with endorsement by qualified person, before the plant is pre-commissioned. All plant and equipment are to be provided with inscriptions and labels to facilitate understanding and safe operation and to satisfy the requirements of any standards and regulations applying to the works. Labelling includes: i)
inscriptions on equipment, cubicles, instruments, process controllers and on small equipment such as relays, control switches, indicating lights, etc
ii)
identification of cables at both ends and along their lengths
iii) identification of terminations for cable cores and cubicle wiring in accordance with the circuit diagrams e)
Drawings submitted shall show all unit processes to be constructed, and equipment to be installed based on the ultimate capacity of the sewerage system, especially for phase development where the construction of unit processes and installation of equipment will be based on phasing.
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f)
4.5.18
Hazardous Areas a)
b)
4.6
For treatment plant with PLC/SCADA systems, ladder diagram, programme source codes and programming console unit shall be provided before pre-commissioning of the treatment plant.
A plan setting out various hazardous areas and classes of electrical hazard is required. For example, flameproof area in the vicinity of anaerobic digesters/sludge gas compressors, chemical storages or laboratories.
Ensure the plant and methods of construction and installation conform to the requirements of each defined area, as this plan will be used by the Supply Authority to inspect the area for conformance.
Material Requirements for STP Structures and Installations Materials permitted for structural fabrication in treatment plants are concrete, reinforced concrete, steel, fibreglass reinforced plastic and aluminium. The requirements for such materials shall be in accordance with information provided in the following sub-sections. Any others material used for STP structures and installations shall obtain special approval from the Commission. Structural design of treatment plant structures shall be submitted by registered professional engineers. They shall be in accordance with the requirements and standards given in this section and any other relevant standards, as well as, sound engineering practices.
4.6.1
Concrete and Reinforcement a)
b) c)
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Concrete structures shall be designed in accordance with MS 1195, except that concrete structures for retaining sewage and other aqueous liquids shall be designed in accordance with BS 8007. Concrete shall generally comply with the relevant requirements in MS 523. Concrete for structures retaining sewage shall have a strength grade not less than grade C35A. Strength grades higher than C35A may be specified as required by the Commission.
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d) e)
f) g)
h)
Concrete for structures retaining sewage shall be designed for buoyancy due to ground condition.
Concrete for purposes other than structures retaining sewage shall have a strength grade not less than grade C20 where unreinforced, and not less than grade C30 where reinforced. Strength grades higher than the minimum may be specified as required by the Commission. Concrete structures retaining sewage, shall be lined with high alumina cement mortar of 20 mm minimum thickness or other approved liners/lining materials.
Concrete and cement mortar exposed to soils or groundwater shall be made using a cement suitably resistant to sulphate attack, as specified in this section. Where part of a concrete structure is exposed to soils or groundwater, cement suitably resistant to sulphate attack shall be used for the entire structure. Cement to be used to resist sulphate attack shall be one of the following: i)
ii)
i) j) k)
Aggregates shall comply with MS 29 and shall be coarse aggregate of 20 mm nominal maximum size.
Approval for admixtures shall be obtained prior to inclusion in the concrete mix. All admixtures shall comply with MS 822. Steel reinforcement shall comply with: ii)
m)
portland pulverised fuel ash cement complying with MS 1227.
iii) ground granulated blast furnace slag complying with MS 1387. iv) high silica content portland cement v) supersuphated cement complying with BS 4248.
i)
l)
sulphate-resisting portland cement complying with MS 1037.
MS 144 for cold reduced mild steel wire. MS 145 for steel fabric.
iii) MS 146 for hot rolled steel bars. Welding of steel reinforcement shall be in accordance with BS 7123. Waterstops for sealing joints in concrete shall comply with MS 1292.
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4.6.2
Steel I)
Structural steel
a)
Structural steel sections shall comply with BS 4 or otherwise with:
i)
EN 10162 for cold rolled steel sections.
ii)
EN 10210 for hot rolled steel sections.
iii) EN 10025 for weldable structural steel. b) c)
iv) EN 10296, EN 10297 and EN 10305 for steel tube.
The use of structural steel in building shall be in accordance with MS 416.
Minor structural steelwork shall be Grade 43A complying with EN 10025. All other steelwork shall be of appropriate grade, as determined using MS 416 and other appropriate standards. These shall be determined by a qualified structural engineer.
II)
Coating for steel
a)
Steelwork that may be in contact with sewage through immersion, splash or spray, or that is over tanks containing sewage, shall be protected against corrosion using one of the following coating systems: i)
high build tar epoxy system complying with AS 3750.2 and applied in two or more coats to give a total dry film thickness of not less than 200 µm.
ii)
high build micaceous iron oxide pigmented epoxy system complying with AS 3750.12 and applied in two or more coats to give a total dry film thickness of not less 200 µm.
iii) hot dip galvanised coating of 140 µm nominal thickness in accordance with MS 740. iv) sealed sprayed zinc coating of 150 µm nominal thickness in accordance with EN ISO 2063. b) Other coatings providing 10 to 20 years service, before first maintenance, as selected using Table 3 Part 8 of BS 5493 shall be considered for approval by the Commission. Steelwork that is exposed to the external atmosphere, except severe marine atmospheres, shall be protected against corrosion using one of the following coating systems:
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i)
ii)
c)
a prime coat of a two pack polyamide cured epoxy zinc phosphate of dry film thickness 60 to 80 µm with a finishing coat of a high build micaceous iron oxide chlorinated rubber paint, spray applied to a dry film thickness of 60 to no more than 80 µm.
hot dip galvanised coating of 85 µm nominal thickness, in accordance with MS 740.
iii) sealed sprayed zinc coating of 150 µm nominal thickness, in accordance with EN ISO 2063.
Steel substrates shall be prepared before application of coatings, in accordance with BS 7079.
d) Other corrosion protection coating systems for steelwork shall be determined using BS 5493 or AS 2312 for tropical atmospheres so as to provide 20 or more years to first maintenance. e) Unprotected steelwork in contact with sewage shall be stainless steel grade 316S31 complying with EN 10088: Part 1 and 3 or EN 10029 and EN ISO 9445. f)
g) h)
Successive coatings of the one component shall be tinted a different colour to facilitate overcoating and inspection. All coatings shall be applied strictly in accordance with the coating manufacturer’s printed instructions. Bolts, nuts, screws and other fasteners shall have either: i)
ii) i)
hot dip galvanised, in accordance with MS 739
sherardized zinc coating, in accordance with BS 4921
iii) electro plating Washers and other small components shall have either: i)
hot dip galvanised, in accordance with MS 740
ii)
a sherardized zinc coating, in accordance with BS 4921
j) Nuts, bolts, screws and washers in contact with sewage shall be stainless steel of Grade 316S31 steel complying with EN 10088: Part 1 and 3 or EN 10029 and EN ISO 9445. k)
Fasteners of incompatible material to the component being fastened shall have suitable isolating washers and sleeves.
III)
Marine and Corrosive Environment
a)
All areas within 5 km from the coast line or salt water bodies shall be classified as marine environment. Sewerage facilities in marine and corrosive environment e.g. where the atmosphere
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b)
or soil contains high levels of chloride, sulphates and corrosive chemical elements or compounds shall be adequately designed to withstand the corrosive actions of the chemicals prevalent in the environment. Necessary protections shall be provided against all corrosive actions of the environment. Design requirement for facilities in marine and corrosive environment shall include: i)
ii) c)
ii)
e)
4.6.3
Concrete shall be resistant to all chemical attacks and be designed in accordance with BS 8110 Part 1: 1997.
Exposed metal shall be of corrosion resistant and of marine grade. Proper smooth surface finishing shall be provided for the metal. Unprotected metals acceptable for use are as follows: i)
d)
Two coats of sodium silicate shall be applied to all external surfaces of concrete structures.
SS316L Aluminium alloy
iii) Materials suitable for use in corrosive environment acceptable by the Commission All structural steelwork shall be thoroughly descaled to BS 7079 second quality and shall be painted with 2 coats of two pack epoxy based red lead primer before leaving the manufacturer’s works. In addition, all structural steelwork shall be provided with protective paint for chloride, sulphate or the prevailing chemicals in the site after installation.
Cathodic protection shall be provided for all load bearing steel structures in marine environment for a minimum life of 50 years.
Fibre Reinforced Plastic (FRP) Only FRP products approved by the Commission shall be used and FRP products shall not be used for access purposes. FRP tanks, vessels and appurtenances for sewage treatment processes shall be designed in accordance with BS 4994 and EN 13923. The thickness of the structural section of the FRP tank wall shall not be less than 5 mm and shall be at least of wall thickness as given in ASTM D 4097. All other FRP products shall meet the requirements of ASTM C 582 for FRP laminates.
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Notwithstanding any other requirements in standards, all FRP products, including FRP tanks and vessels for sewage treatment processes, shall conform to the following material requirements: a)
FRP properties shall be as determined by design to standards mentioned in this Section and other relevant standards, but shall not be less than the following values:
− − − − − − − − −
Tensile strength - 80 MPa Tensile modulus - 7000 MPa Flexural strength - 140 MPa Flexural modulus - 6000 MPa Water absorption - ≤ 0.75 % Barcol hardness - 40 Operating temperature - -40oC to +50oC Specific gravity - ≥ 1.5 Fire rating – ASTM E84, < 25s or Class 1 BS476
b) Unsaturated polyester resins shall be used but shall only be isophthallic, bisphenol A fumurate or terephthalic polyester resins meeting the requirements of Type B or C of BS 3532. c)
d)
e) f)
All surfaces shall have a resin rich layer, gel coat. Surfaces in contact with sewage, water or any moisture shall comprise of a resin rich layer at least 1 mm thick. All other surfaces shall comprise of a resin rich layer at least 0.25 mm thick. Up to 10% by mass of corrosion resistant glass fibres, (that is, C-glass or E-CR glass), polyester fibres or acrylic fibres may be used in the surface layer. A barrier layer shall be provided behind the surface layer and shall be at least 1.5 mm thick. The barrier layer shall comprise of 70 to 80 % by weight resin with the remainder by weight being E glass or E-CR glass. The structural layer shall comprise resin impregnated layers of E glass or E-CR glass and shall comprise at least 25 % E glass or E-CR glass. Aggregate and filler may be included. E glass and E-CR glass shall conform to the requirements of: i)
ii)
EN 14020 for glass rovings.
EN 14118 for chopped strand mat.
iii) BS 3396 for woven fabric.
iv) BS 3749 for woven roving fabric.
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g) h)
i) j) k) l)
Glass fibres shall have a surface treatment compatible with the manufacturing process to ensure bonding to the resin. Aggregates shall only be used in FRP structural layers and external layers. Aggregates shall be clean, washed, high grade silica sand containing not less than 95 % silica. Aggregates shall be of a size not greater than 20 % of the thickness of the FRP structural layer with a particle size not less than 0.05 mm and not greater than 5 mm. Fillers shall only be used as a resin extender and shall comprise of clean inert material, for example, silica, with particle size less than 0.05 mm.
Surfaces exposed to sunlight shall incorporate provisions to minimise ultraviolet degradation, such as, ultraviolet inhibitors, screening agents or pigment in the outer resin rich layer. Pigments and dyes shall not normally be required, but where required by the Commission, shall be of a type and colour specified by the Commission. FRP water tanks shall comply with the above requirements and requirements in: i)
m)
n) 4.6.4
ii)
MS 1241: 1991 where not constructed of FRP panels. MS 1390: 1995 where constructed of FRP panels.
All design of package plants using FRP materials shall take into account for the buoyancy effects. This effect is of concern during high ground water conditions and emptying of the tank content during desludging works. Anchor strap shall be at least stainless steel grade 304.
Aluminium a)
b)
Aluminium is found primarily as the ore bauxite and is remarkable for its resistance to corrosion (due to the phenomenon of passivation) and its light weight. Structural components made from aluminium and its alloys are very important in which light weight, durability, and strength are needed. Wrought aluminium and aluminium alloys shall comply with: i)
ii)
BS 1161 for structural purposes.
EN 485 for sheet plate and strip.
iii) EN 754 for drawn tube.
iv) EN 755 for bars, extruded round tubes and sections.
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v)
EN 1676 for ingots and castings.
vi) BS 4868 for profiled sheet. c) d)
4.6.5
Anodic oxidation coating on aluminium shall be in accordance with EN 12373. Requirements for structural design, materials, workmanship and protection of aluminium shall be in accordance with BS 8118
HDPE (High Density Polyethylene) High-density polyethylene (HDPE) is the high density version of PE plastic. Its molecules have an extremely long carbon backbone with no side groups. As a result, these molecules align into more compact arrangements, accounting for the higher density of HDPE. HDPE is stiffer, stronger, and less translucent than low-density polyethylene. HDPE is lighter than water, and can be moulded, machined and joined together using welding. High-density polyethylene shall comply to the following physical properties:−
Tensile Strength
0.20 – 0.40 N/mm2
−
Notched Impact Strength
no break Kj/m2
Max Cont Use Temp
650C
− − − −
Thermal Coefficient of expansion Density
Minimum Require Strength
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100 – 220 x 10-6 0.944 – 0.965g/cm3 8.0 MPa
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5.1
Introduction All new applications for sewage treatment plant approval shall follow the design requirements as stipulated in this section. These requirements have been formulated as a gradual change in sewage treatment methods for Malaysia prior to enforcement of ultimate requirements as stipulated in Sections 3 and 4 of this volume. Design requirements for each stage of the sewage treatment process, as shown in Figure 5.1 are given in this section. Figure 5.2 gives an overview of the typical flow diagram and elements of a sewage treatment plant. Figure 5.2 also shows how one facility is closely related to another and thus has an impact upon the overall design. Sewage treatment plants must be designed to produce an effluent quality that conforms to either Standard A or Standard B or any other special requirements under the provisions of the Environmental Quality Act. The major indices are those of BOD5, Suspended Solids, COD, Oil & Grease, Ammoniacal Nitrogen, Nitrate Nitrogen and Total Phosphorus. The requirement to comply with absolute standards, where no failures are permitted by law, means that new sewage treatment plants must be designed to produce average effluent qualities well below those permitted by the Standard figures. Design values for final effluent shall be used in the design of new treatment works are given in Table 3.2. These design effluent levels serve as the basis for the design requirement of each unit process given in the following sub sections. General ventilation systems shall be provided in compliance to the OSHA. The potential for odour generation, its impact and treatment, shall be considered in all aspects of design. Odour treatment equipment shall be selected that such odours be reduced to the lowest possible level and in compliance to the EQA.
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Figure 5.1 Typical Treatment Process Flow Chart Figure 5.1 Typical Treat ment Process Flow Chart Treatment Stage
Pre Treatment
Primary Treatment
Secondary Treatment
Treatment Processes 1
Primary Screen
2
Pump Station
3
M
Design Requirements Section 5.2
Function
Removes rocks, roots and rags
Lifts sewage and provides consistent flow to the treatment system
M/O
Section 5.3
Secondary Screen
M
Section 5.4
Removes smaller/finer particles from sewage
4
Grit/Grease Removal
M
Section 5.5
Removes sand, gravel and other inorganic materials; separates oil & grease
5
Balancing Tank
M/O
Section 5.6
Balances and equalises flow
6
Primary Sedimentation
M/O
Section 5.7
Removes settleable solids/materials
7
Biological Treatment
M
Section 5.8
Remove major polutants (BOD and SS)
8
Secondary Sedimentation
M
Section 5.9
Separates treated effluent and settled sludge
Disinfection
M
Section 5.10
Destroy disease causing organisms
Flow Meter
M
Section 5.11
Measures and records flows
9
10
Bio Solids Handling
Requirements Mandatory (M) Optional (O)
11
Thickener Stabilisation Holding Dewatering
M/O
Section 5.12
Reduces potential detrimental effect on the environment and converts sludge to a form suitable for ultimate disposal
Sludge Disposal 82
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M al aysi an S ewerage I ndustry G ui del i nes
Raw Sewage Inlet
2
Sewage Treatment Plants
Sewage Treatment Plants
Ultimate Disposal
4
5
Balancing Tank
Sludge Storage Area
Grit/Grease
Secondary Screen
Incinerator/Dryer
Sewage Pump Station
Primary Screen
1
3
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Sludge Drying Bed
Mechanical Sludge Dewatering
Alternate
Alternative
Primary Clarifier
6
Alternative
8
Final Clarifier
Mechanical Sludge Thickener
Flow Distribution
Sludge Holding Tank
Sludge Digester
Liquor
Return Sludge Pump Station
C. Trickling Filter D. RBC
B. Extended Aeration Activated Sludge
A. Conventional Activated Sludge
Biological System
7
9
Disinfection 10
Effluent To Nearest Receiving Watercourse
Flow Meter
Requirements for Stages of Sewage Treatment Requirements for Individual Treatment Processes
Figure5.2 5.2 Typical Typical Elements Process Diagram of a Figure Elements and and Process Flow Flow Diagram of a Sewage Sewage Treatment Treatment PlantPlant
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5.2
Design of Primary Screens
5.2.1
Purpose of Primary Screens Upon reaching the sewage treatment plant, sewage flows through the primary screening facility which is the first stage of treatment. The screens must be provided upstream of all inlet pump stations and shall be designed to protect downstream processes and equipment. The purposes of primary screens are: a)
b) 5.2.2
to protect equipment from rags, wood and other debris
to reduce interference with in-plant flow and performance
Inlet Chamber Provision for inlet chamber before the primary screen channel is necessary for proper operational and maintenance. The summarised requirements for inlet chamber are as follows: Table 5.1 Requirements for Inlet Chamber
Unit Process
Requirements
> 20 000 PE
> 50 000 PE
Yes
n/a
n/a
Dual
n/a
Yes
Yes
Motorised
n/a
No
Yes
Inlet Chamber
Type
≤ 20 000 PE
Single
Mandatory
Notes
Single and dual penstocks are referring to members of penstocks required. For more than 50 000 PE, the main penstock must be motorised.
n/a – Not applicable a) b) c)
84
A penstock shall be installed upstream to isolate the pump station in the event of flooding in relation to the bypass and emergency overflow.
For safety reasons, a double penstock system shall be provided at the inlet works of all plants with pump station above 20 000 PE.
The penstock spindle shall extend to pump station ground level and shall be suitably positioned to allow unrestricted operation of the penstock.
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Figure 5.3 Typical Details of Double Penstock
CLEAR SPACING MANUAL FINE SCREEN
FIRST PENSTOCK
SECOND PENSTOCK
OVERFLOW PIPE DISCHARGETO DRAIN
PRIMARY SCREEN CHAMBER
INLET CHAMBER
450mm
1:2
5.2.3
IL
Design Requirements for Primary Screens Table 5.2
Provision of Primary Screens Numbers of Primary Screen
Requirements
Duty Standby
≤ 5000 PE
> 5000 PE
1 Unit
-
Mechanical
-
1 Unit
Manual
-
-
Mechanical
-
1 Unit
1 Unit
1 Unit
Manual
By Pass
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Table 5.3 Design Parameters for Primary Screens
Description
Unit
Maximum clear spacing
mm
Slope to the vertical
Design Criteria Manually Mechanically Raked Raked# 25
25
30o – 45o
15o – 45o
Maximum approach velocity at the feed channel
m/s
1.0
1.0
Maximum flow through velocity at the screen face
m/s
1.0
1.0
Minimum freeboard
mm
150* 30
150
See Figure 5.4
day
7
7
Estimated volume of screenings per volume of sewage
m3 / 106 m3
screenings skip storage capacity Minimum channel width Minimum channel depth
RC Staircase with riser detail
mm
500
500
1 unit
Anti-skid and non-corrosive
Anti-skid and non-corrosive
mm
500
500
Notes: * Designer shall ensure that with 50% of blockage at the face of screen, sufficient freeboard is provided to prevent the approach channel from overflowing #
Washing and dewatering of screenings shall be provided.
5.2.4
General Requirements All plants must include: a)
An emergency manual bypass screen. In the event of system failure and/or power outages, the flow shall be automatically directed to the bypass. It shall also be able to cope with maximum flow.
b)
Hand railings, kick plates, standing platforms and other safety features to improve maintenance
Screen chambers must be of open channel construction with proper ventilation. Forced ventilation must be used if chambers are enclosed.
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Screens must be designed to withstand the flushing velocity. In the event of the manual bypass screen being blocked, sewage must be able to flow over the top of the screen without causing excessive backup flooding or overflows. Chambers design must have taken into consideration necessary health and safety aspects. The chamber must also be hydraulically efficient to prevent the settlement of solids in the chamber. Macerators and communitors as replacements for primary screens are generally not recommended. It may be considered if the consultant is able to provide good engineering reasons for its application. Reinforced concrete staircase with proper handrailing must be provided to access screen chambers. Shaftless screw conveyors and belt conveyors may be used where required. The screw conveyor shall be equipped with easy to remove covers. The frame and support of screw conveyor shall be of minimum stainless steel Grade 304 while the screw shall be of high tensile steel. The belt conveyors shall be of heavy duty reinforced rubber belts on a protected mild steel frame. Conveyors shall normally be installed on a very slight grade to allow drainage, with foul water returned to the inlet channel. All screenings raked from mechanical screen shall be dropped into a skip. A proper standpipe shall be provided and located within 3 m to the screen chamber. Figure 5.5 and 5.6 illustrate typical arrangement of screen chambers of various depths. Refer also to relevant clause of MS 1228 for more details.
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Requirements Individual Treatment Processes Requirements for for Stages of Sewage Treatment
Figure ScreeningsCollected CollectedFrom From Primary Screens Figure 5.4 Quantities Quantities of of Screenings Primary Screens
100
80
Screenings, m 3/ 10 6m 3 of Sewage
Average Maximum 60
40
20
0
0
1
2
3
4
5
6
Opening Between Bars, cm
88
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A
INCOMING SEWER
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INCOMING SEWER
R.C STAIRCASE TO ENGR'S DETAIL
HANDRAIL
HANDRAIL
PENSTOCK
R.C STAIRCASE TO ENGR'S DETAIL
PENSTOCK
CHAIN GUARD
GRATING COVER
MECHANICAL COARSE SCREEN
CONC. APRON LAID TO FALL
PLAN (PE > 5000)
SECTION A-A
STOP LOG
DRAIN
RAMP DOWN
A
PERFORATED SLAB
SCREENINGS COLLECTION BIN
WP
A
GRATING COVER
HANDRAIL
HANDRAIL
PENSTOCK
PENSTOCK
CHAIN GUARD
INCOMING SEWER
R.C STAIRCASE TO ENGR'S DETAIL
INCOMING SEWER
STOP LOG
CONC. APRON LAID TO FALL
DRAIN
SECTION A-A
PLAN (PE ≤ 5000)
R.C STAIRCASE TO ENGR'S DETAIL
RAMP DOWN
WP
S.S PERFORATED TROUGH
SCREENINGS COLLECTION BIN
A
Requirements for Stages of Sewage Treatment
Requirements for Individual Treatment Processes
Figure 5.5 Typical Drawing of Screen Chamber based on depth Figure 5.5 Typical Drawing of Screen Chamber based on depth (<5 m for different PE) (<5m for different PE)
< 5m
< 5m
89
77
< 5m
INCOMING SEWER
STOP LOG
R.C STAIRCASE TO ENGR'S DETAIL
HANDRAIL
HANDRAIL
PENSTOCK
R.C STAIRCASE TO ENGR'S DETAIL
INCOMING SEWER CHAIN GUARD PENSTOCK A
M.S GRATING COVER
DRAIN CONCRETE APRON LAID TO FALL
SECTION A-A
MECHANICAL COARSE SCREEN
PLAN VIEW (PE > 5000)
RAMP DOWN
DN
WP
OPENINGS
CAT LADDER
R.C PERFORATED SLAB
SCREENINGS COLLECTION BIN
A
MECHANICAL COARSE SCREEN
R.C STAIRCASE TO ENGR'S DETAIL
> 5m INCOMING SEWER STOP LOG
HANDRAIL
PENSTOCK
R.C STAIRCASE TO ENGR'S DETAIL
CHAIN GUARD PENSTOCK
HANDRAIL
A
M.S GRATING COVER INCOMING SEWER
DRAIN CONCRETE APRON LAID TO FALL
SECTION A-A
PLAN VIEW (PE ≤ 5000)
RAMP DOWN
A
MANUAL COARSE SCREEN
OPENINGS
S.S PERFORATED TROUGH
CAT LADDER
R.C PERFORATED SLAB
SCREENINGS COLLECTION BIN
DN
WP
Requirements for Individual Treatment Processes
Requirements for Stages of Sewage Treatment
Figure 5.6 Typical Drawing of Screen Chamber based on Depth. (>5 m for different PE)
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5.3
Design of Pump Stations
5.3.1
Purpose of Pump Stations Inlet pump stations must be preceded by primary screens to protect the pumps from being damaged or clogged. The inlet pumps of the treatment works must be capable of handling raw unscreened sewage. Water pumps must not be used as they are not designed to cope with matters that may be found in sewage and the variability and quantity of sewage flow. The purposes of pump stations are: a)
to lift sewage to a higher point for treatment
c)
to prevent overflow of raw sewage
b)
5.3.2
to provide consistent inlet flows to the treatment system
Design Requirements (I)
Structural Requirements
a)
Substructure shall be constructed with reinforced concrete using cement resistant to chemical attack, aggressive soils and groundwater.
b) c) d) e) f) g)
Safe and suitable access to the wells shall be provided.
If cement used is not resistant to the chemical attack, internal walls shall be made resistant to sulphide corrosion by coating with high alumina cement or approved equivalent coating. A controlled overflow from the last manhole upstream of the pump installation shall be provided to allow emergency maintenance works. Access shall be provided at all locations where operation and maintenance works take place. Static screen shall be provided at specific locations where it needs to protect downstream unit processes. Access covers shall be hinged with a lifting weight not exceeding 16 kg.
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Requirements for Individual Treatment Processes
II)
Ventilation Requirements
a)
Ventilation shall be provided for all hazardous zones of the pump station. Below ground pits shall have mechanical ventilation. Separate ventilation shall be provided for wet wells and dry wells. Lighting systems shall be interconnected with ventilation. Permanent ventilation rate and air changes shall comply with Section 6 of this Guidelines.
b) c) d) e) III)
Odour Control Requirements
a)
Isolate odorous gases from general ventilation by containing identified odour generating sources with a separate local exhaust system. Containment of the odour sources shall be by installing lightweight and corrosion resistant covers/enclosures designed for practical operation and maintenance works. Local exhaust rates for containment shall be designed to provide a negative pressure preventing build up of toxic, corrosive or explosive gases and to include provision for process air or air displaced by changes in the level of liquid inside the covered space. The odourus air in the local exhaust system shall be conveyed through well designed and balanced ductworks by a centrifugal fan to an effective odour treatment system. Odour treatment equipment shall be selected such that odour is reduced to the lowest possible level and in compliance to the EQA. In situation where specific gases such as hydrogen sulphide and ammonia are significantly present, provide a pre-scrubber unit upstream of the main odour treatment equipment. Containment, exhaust and treatment shall be designed as an integrated package.
b) c)
d) e) f) g) h)
Consideration must be given to the life span of the odour control system and associated costs in operating and maintaining such a system.
IV) Wet Wells Requirements a)
92
Suction channels shall be designed to avoid “dead zones”, i.e., prevent solids and scum accumulation. All “dead zones” shall be chamfered.
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b) b) c) c) d) d) e) e) f) f) g) g) h) h) i) i)
Benching shall shallbebe such to minimise deposition solid Benching such that that to minimise deposition of solid of matters matters on the floor or walls of wet wells. The minimum slope on the floor or walls of wet wells. The minimum slope of benching of benching be 45o to the horizontal. shall be 45o toshall the horizontal.
Benching shall shallpreferably preferably extended the pump Benching be be extended up toupthetopump intake.intake. Minimum hopper hopper bottom bottom slope slopeshall shallbe be1.5 1.5vertical verticaltoto1.0 1.0horizontal. horizontal. Minimum Tapered slope slopeshall shallbebe provided upthe to suction the suction section. Tapered provided up to section.
Automatic flushing flushingofofgrit gritand andsolids solids recommended plants Automatic is is recommended for for plants of of PE > 2 000. PE > 2,000. The difference differencebetween betweenstop stopand andstart start levels shall a maximum The levels shall be abemaximum of of 900 mm and a minimum of 450 mm. 900 mm and a minimum of 450 mm. The difference difference in in level level between between start start oror stop stop ofof duty duty and and assist assist The pumps shall be greater than or equal to 150 mm. pumps shall be greater than or equal to 150 mm. The minimum internal width of wet well shall not less than 2m. The minimum internal width of wet well shall not less than 2m Where possible, wet wells shall be open and guarded by a handrail Where possible, wet wells shall be open and guarded by a handrail or open mesh grating. The grating shall be easily and safely or open mesh grating. The grating shall be easily and safely removed. removed. Figure ofWet WetWell Well Figure 5.7 5.7 –Typical Typical Dimensions Dimensions of Submersible PumpStation Station Submersible Pump MIN 2000 (ℓ/S) QO (I/S) i
INCOMING SEWER Qi (I/S) (ℓ/S)
D2
HIGH LEVEL ALARM
≥ 150
STANDBY CUT IN LEVEL
d
CUT IN LEVEL
s
CUT OUT LEVEL
k
LOW LEVEL ALARM
D1
Note : Q1 = Incoming flow rate QO = Forcemain Discharge rate D2 = Forcemain Diameter, min 100 d
= Difference between stop & start level, Min 450 Max 900
s
= Minimum submergence, depends on manufacturer recommendation
k
= Minimum clearance between pump suction and wet-well invert
All dimension are in mm unless otherwise state
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Figure 5.8 Typical Dimensions of Dry Well Figure 5.8 – Typical Dimensions of Dry Well Submersible Pump Station Submersible Pump Station IN Qi COMI (I/S NG SE ) W
ER
HIGH LEVEL ALARM
150
STANDBY CUT IN LEVEL
D
CUT IN LEVEL CUT OUT LEVEL LOW LEVEL ALARM/EMERGENCY CUTOUT
2
D1
150
D2 to D2
S
3 D2 to D2 4
D2
QO (l/s)
150 (min)
ALLOW ADDITIONAL DEPTH FOR SOLID HEAVY OBJECTS
IN Qi COM (I/S I NG SE ) WE R
150 S
HIGH LEVEL ALARM STANDBY CUT IN LEVEL
D
CUT IN LEVEL CUT OUT LEVEL
D2 TO D2
D2
LOW LEVEL ALARM/EMERGENCY CUTOUT
Q0 (l/S)
150
D1
Note : Q1 = Incoming flow rate QO =
Forcemain Discharge rate
D2 =
Bellmouth Diameter
ALLOW ADDITIONAL DEPTH FOR SOLID HEAVY OBJECTS
D1 = Suction Diameter, Min 100 D = S
Difference between stop start level, Min 450 and Max 900
= Minimum depth above pump intake to prevent vortex formation
V) (V)
Lighting Requirements Lighting Requirements
a) a) b) b)
Wet wells and dry-wells shall be adequately lit. Wet wells and dry wells shall be adequately lit. Electrical installations installationsshall shallbebewater waterproof and vapour vapour proof prooforor Electrical proof and explosion proof. explosion proof.
c) c)
If lights lights are arefitted fittedoutside outsidethethe well, then a spotlight system If well, then a spotlight system may may be be used to provide adequate illumination. used to provide adequate illumination.
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VI)
Level Controls
a)
Either floats or ultrasonic level controller may be used for the start-stop levels of pumps. Instrument with environmental friendly features are recommended. Ultrasonic level control is recommended due to its clog-free nature. Non-mercury type floats are recommended. Hollow tube electrodes are not acceptable. Level controller shall be placed where they are not affected by the turbulence of incoming flow and where they can be safely removed.
b) c) d) e)
VII) Pump Hydraulic Design a)
The submission of pump hydraulic design and performance shall include: i)
ii)
System curves Pump curves
iii) Operating points of pumps with respect to flow and total dynamic head (TDH)
b) c) d) e) f) g)
5.3.3
iv) Operating characteristics such as efficiency, horsepower and motor rating
Pump shall be operating within their best efficiency range at normal operating condition. Pumps are to be equipped with an auto restart mechanism in the event of power failure.
Dry-well mounted pumps shall be equipped with auxiliary services such as cooling and gland seal water supply.
Pumps equipped with cutting or macerating facilities are not acceptable. Guide rail, lifting device and other wet well fittings must be fabricated of stainless steel that is corrosion resistant. The use of hot dip galvanised iron is not recommended.
Horizontal installation of pumps is not allowed. All pumps shall be installed vertical, unless the Consultant is able to provide good engineering reasons for horizontal installation.
General Requirements a)
Drainage of dry-wells and valve pits shall be provided. Drainage lines shall be equipped with back flow protection to ensure that the chamber is not flooded.
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b)
The wet well shall not be housed with a building structure.
d)
Pipework
c)
Where separate valve pits are used, the connecting pipes shall incorporate at least two flexible joints to allow for differential settlement. i) Pipe work shall be of ductile iron or cast iron with cement internal lining. Other approved material by the Commission may be used. ii) External surface of pipework in chambers and wells shall be epoxy coated. iii) Buried ductile iron pipe shall have polyethylene sleeving. iv) Pipe within wells and pits shall have flanged joints, while pipe laid in the ground shall have spigot and socket joints. v) Pipe work shall be adequately supported on concrete plinths or steel structural supports. vi) Flanges shall be located at least 150 mm away from structures. vii) Dismantling joints such as bends shall be provided. viii) Pumping thrust shall be resisted using pipe supports inside chambers and by mass concrete thrust blocks poured against undisturbed soil in the ground outside chambers. ix) No welding joints are allowed.
e) Valves i) Gate valves are preferred with rising spindles operated by a tee piece. ii) The uses of counterweights are recommended. Tapping (12 mm BSP) shall be located upstream and downstream of check valves. Also refer to additional requirements in relevant Clause of MS 1228.
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Figure 5.9 Typical Details of Wet-well Pump Station Figure 5.9 Typical Details of Wet-well Pump Station
MECH. COARSE SCREEN INCOMING SEWER
STEPS
GRATING COVER
OVERFLOW PIPE DISCHARGE TO DRAIN
V.C.P STAND PIPE CONC. APRON
COLLECTION BIN CLEAR SPACING S.STEEL MANUAL FINE SCREEN
OVERFLOW CHAMBER
INFLUENT PUMP PRIMARY SCREEN
A GRATING COVER 17 18 19 20 21 22 23 STEPS
A PUMP SUMP
S.STEEL HANDRAIL PENSTOCK
16 15 14 13 12 11 10 9 8 7 6 5 4 3 2
EXPLOSION PROOF SPOT LIGHT CHECK VALVE FLEXIBLE COUPLING GATE VALVE
1
DELIVERY PIPE
R.C STAIRCASE TO ENGR'S DETAIL
PLAN VIEW LIFTING I-BEAM C/W CARRIER HANDRAIL CLEAR SPACING MANUAL FINE SCREEN
MECH. COARSE SCREEN CHAIN GUARD CHECK VALVE FLEXIBLE COUPLING GATE VALVE DELIVERY PIPE
PENSTOCK
OVERFLOW PIPE DISCHARGE TO DRAIN
NON-EXPLOSION SPOT LIGHT
OVERFLOW CHAMBER
DELIVERY PIPE GUIDERAIL
S.S PERFORATED TROUGH
PUMP SUMP
LIFTING CHAIN
PRIMARY SCREEN CHAMBER CONC. SLAB R.C WALL TO ENGR'S DETAIL
IL
1:2
IL
FRP STOP LOG C/W HAND WHEEL IL
OPENING ALARM START
MANUAL COARSE SCREEN STOP
SECTION A-A
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Requirements for Individual Treatment Processes Requirements for Stages of Sewage Treatment
Figure Typical Details of Dry-well Pump Station Figure5.10 5.10 Typical Details of Dry-well Pump Station OVERFLOW PIPE DISCHARGE TO MONSOON DRAIN
OVERFLOW CHAMBER DRAIN
RAMP DOWN
CONC. APRON LAID TO FALL
3 LAYER CONC. VENTILATION BLOCK AT TOP AND BOTTOM LEVEL
LIQUID RETURN FROM OTHER UNIT PROCESSES
WP
FORCEMAIN MECHANICAL COARSE SCREEN
A
A
GATE VALVE.
NCOMING SEWER AIR EXTRACTOR FAN
14 15 16 17 18 19 20 21
R.C STAIRCASE TO ENGR'S DETAIL
G.I CHAIN GUARD.
G.I CHAIN GUARD PENSTOCK GRATING COVER
3 LAYER CONC. VENTILATION BLOCK AT TOP AND BOTTOM LEVEL
CHECK VALVE.
CONC. THRUST BLOCK.
12 11 10 9 8 7 6 5 4 3 2 1
CONC. THRUST BLOCK.
EXTRACTOR FAN R.C STAIRCASE TO ENGR'S DETAIL. CONCRETE VENTILATION BLOCK AT TOP AND BOTTOM LEVEL
DN
CHAIN GUARD.
DN 13 12 11 10 9 8 7 6 5 4 3 2 1
13 14 15 16 17 18 19 20 21 22 23
ADJUSTABLE GLASS LOUVRES WINDOW
SPOT LIGHT CHEQUER PLATE
DOOR
BRICKWALL C/W CEMENT PLASTER ON BOTH SIDES DRY PIT PUMPS
PLAN VIEW COPPER TYPE LIGHTNING ARRESTOR
LIFTING I-BEAM C/W CARRIER
RAIN WATER DOWN PIPE TO NEAREST SUMP
MECHANICAL COARSE SCREEN
PENSTOCK HANDRAIL
R.C GUTTER TO ENGR'S DETAIL
DOOR
SCREENINGS COLLECTION BIN
BRICKWALL C/W CEMENT PLASTER ON BOTH SIDES WINDOW
CHEQUER PLATE
3 LAYER CONC. VENTILATION BLOCK
HANDRAIL R.C STAIRCASE TO ENGR'S DETAIL
WET WELL
DRY WELL
PERFORATED SLAB CAT LADDER OPENINGS
INCOMING SEWER
(FLOAT SWITCH)
CHECK VALVE
2nd. STANDBY PUMP START 2nd. DUTY PUMP START
GATE VALVE
1st.. DUTY PUMP START
ALARM 1st. STANDBY PUMP START
ALL PUMP STOP
STOP LOG
SUMP BWL
DEWATERING PUMP
DRY PIT PUMPS
SECTION VIEW
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Requirements for Individual Treatment Processes
Table 5.4 Recommended Design Parameters for Inlet Pump Stations ≤ 1000 Design Parameters Description
Unit
Type of station Number of pumps (all identical and work sequentially) Pumps design flow
PE ≤1,000
1,000 < PE ≤ 5,000
Wet well 2 1 duty, 1 standby (100 % standby) Each at Q
Wet well 2 1 duty, 1 stand-by (100 % standby) Each at Q
peak
peak
Maximum retention time at Q
min
30
30
Min pass through openings Minimum suction and discharge openings Pumping cycle (average flow conditions) Lifting device*
mm
75
75
mm
100
100
ave
start/ hour
6 min 15 max Lifting davit
6 min 15 max lifting beam and block
Design Parameters Description
Type of station
Unit
5,000 < PE ≤ 20 000
Wet well or dry-well up to 10,000 PE 10,000 PE above – wet well and dry-well 4 (2 sets) 1 duty, 1 assist, per set (100 % standby)
Number of pumps (all identical and work sequentially)
PE > 20,000
Wet well and dry well 6 (3 sets) 1 duty, 1 assist, per set (50 % standby)
min
each at 0.5 Qpeak 30
each at 0.25 Qpeak 30
Min pass through openings
mm
75
75
Minimum suction and discharge openings Pumping cycle (average flow conditions)
mm
100
100
start/ hour
6 min 15 max
6 - 15
Pumps design flow Maximum retention time at Qave
Lifting device*
Mechanical and block
mechanical
Note: * Motorised hoists shall be provided when the lifting weight exceeds 100 kg
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5.4
Design of Secondary Screens
5.4.1
Purpose of Secondary Screens After the inlet pump station, further screening is required to reduce the remaining floating matter and finer particles in the sewage that will disrupt the treatment process downstream. The purposes of secondary screens are: a) b)
5.4.2
to remove material such as plastic, paper, cloth and other particles that may cause problems to the treatment process downstream.
to minimise blockages in sludge handling and treatment facilities.
Design Requirements Plants of all sizes must be installed with secondary screens. The channel shall be designed for Qpeak or pump flow whichever is greater. Approach channel shall be design to ensure good contribution of velocity A minimum of two screens are required for duty and standby. Facility for a screened bypass must be provided in the event of clogging. Where mechanically cleaned screening devices are installed auxiliary manually cleaned screen shall be provided. Table 5.5 Provision Requirement of Secondary Screens Requirements
Duty Standby Bypass
100
Manual
Mechanical
Manual
Mechanical
Screen
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Numbers of Secondary Screen ≤5000 PE >5000 PE
1 Unit
-
-
1 Unit
-
1 Unit
-
1 Unit
-
1 Unit
Malaysian Sewerage Industry Guidelines
Requirements for Individual Treatment Processes
Table 5.6 Design Parameters for Secondary Screens
Description
Unit
Maximum clear spacing
mm
Maximum approach velocity at the feed channel Maximum flow through velocity at the screen face Minimum freeboard
Slope to the vertical
Estimated volume of screenings per volume of sewage Screenings skip storage capacity Minimum channel width Minimum channel depth RC Staircase with riser detail
Design Criteria Manually Mechanically Raked Raked # 12 30o – 45o
12 15o – 45o
m/s
1.0
1.0
m/s
1.0
1.0
mm
150*
150
m3 / 106 m3 day mm mm 1 unit
See Figure 5.4 7 500 500 Anti-skid and non-corrosive
7 500 500 Anti-skid and non-corrosive
Notes: * Designer shall ensure that with 50% of blockage at the face of screen, sufficient freeboard is provided to prevent the approach channel from overflowing # Washing and dewatering of screenings shall be provided.
5.5
Design of Grit and Grease Chambers
5.5.1
Purposes of Grit and Grease Chambers This unit process is important to minimise problems associated with grit and grease. Grit creates problems to pumps and also sludge digestion and dewatering facilities. Grease creates problems at the clarifier and is carried over in the final effluent. In grit removal system, grit or discrete particles that have subsiding velocities or specific gravities substantially greater than those of organic putrescible solids, e.g. eggshells, sands, gravel are removed by gravitate settlement or centrifugal separation. Same principle apply to oil and grease removal system, where free oil and grease globules lighter than water rise through the liquid and skimmed from the top surface.
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The particles must be removed at an early stage of the process because: a) b) c)
5.5.2
the grit particles cannot be broken down by any biological treatment.
the grit particles are abrasive and wear down equipment.
the biological treatment in sewage treatment works is not designed to degrade grease.
General Requirements A manual bypass shall be provided. In case of grit removal system failure and/or power outages, the flow shall be automatically directed to the bypass. Where mechanical grit separator is used, they shall be installed at an angle of at least 10° to allow drainage and foul water to be returned to the inlet channel. Where manual systems are used, allow for safe and easy access to remove grit to a storage bin. If pump systems are used, the suction pipe shall be short and straight. Tees and short radius bends shall be avoided, if at all possible. Flanges at strategic locations shall be provided so that they can be dismantled to remove any blockages. The mechanical oil and grease skimming device shall be designed to minimise the water being remove while skimming the oil and grease. Sand pit may be used for further dewatering of the grease removed before ultimate disposal. The drainage from the sand pit shall be returned to the inlet channel for further treatment.
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Table 5.7 Provision Requirement of Grit and Grease Removal System Number of Unit Processes
Requirements
i) Grit Removal System Duty
Manual Mechanical
≤ 5000 PE
> 5000 PE
1 Unit @ design flow
-1 Unit @ design flow (up to 10 000 PE) -2 unit @ 50% design flow each ( >10 000 PE) Yes
Standby
Manual Mechanical
1 Unit @ design flow Bypass ii) Grease Removal System Duty Manual 1 Unit Mechanical Standby Bypass
5.5.3
Manual Mechanical
1 Unit @ design flow -
-1 Unit @ design flow (up to 10 000 PE) -2 unit @ 50% design flow each ( >1000 PE) Yes
Design Criteria Design criteria are given in Tables 5.8 and 5.9. Table 5.8 Design Parameters for Grease Chambers Description
Unit
PE ≤ 5000*
Design Criteria > 5000PE
Grease removal
-
Chamber type
-
Rectangular
Baffled tank
Aerated type
min
3
3
3
Minimum detention time (Qpeak)
Simple manual Manual interceptor
> 5000PE
Mechanical
Grit and grease storage period before off-site day 30 7 7 disposal Note: * Combined grit & grease chamber is allowed. If combined, then total detention time shall comply to 6 minutes at Qpeak. Sewage Treatment Plants
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Table 5.9 Design Parameters for Grit Chambers Description
Unit
Design Criteria PE ≤ 5000*
>5000PE
>5000PE
Grit removal
-
Manual (tanker)
Mechanical
Mechanical
Chamber type
-
Horizontal flow (2 units required for duty and standby during cleaning) vortex also acceptable
Square, rotary or vortex type simple mechanised grit chamber
Aerated
minute
3
3
3
m/s
0.20
0.20
0.20
m/s
n/a
<1.0
<1.0
-
35% of depth
-
l/s/meter length of tank
-
-
10.0
-
1:2
Manufacturer’s Specification
Manufacturer’s Specification
Minimum detention time at Qpeak
Maximum gravity flow through velocity at Qpeak Maximum centrifugal flow through velocity
Head loss (at parshall flume) Aeration requirement Chamber dimension: Depth: Width Length: Width Estimated grit quantity Washing and dewatering of grit
2:1 m3/103 m3 of sewage
0.03
0.03
0.03
-
No
Yes
Yes
Notes: * Air lift pump for removal of grit is not acceptable. * Water depth in tank to be controlled by weir outlet.
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5.6
Design of Balancing Tanks Balancing tanks are mandatory for all treatment processes that are not designed at peak flow. The tanks are effective means of equalising sewage flow. For extended aeration plants that are designed with a retention time of more than 18 hours and clarifiers designed at peak flow, the use of balancing tanks is not required.
5.6.1
Purposes of Balancing Tanks The purposes of balancing tanks are to: a)
prevent flow variations entering secondary treatment processes.
c)
reduce potential overflows that may cause health hazard and pollution.
b)
5.6.2
reduce hydraulic loading into secondary treatment processes.
Design Requirements The design requirements for balancing tanks are: a)
All balancing tanks must be completely aerated and mixed.
c)
Allowance must be made for an emergency overflow.
b)
d) e) f)
Flow control shall be by a non-mechanical constant flow device, such as an orifice, in order to avoid double pumping. Bypass and drain down facilities as well as suitable access for cleaning shall be provided. A dead water depth of 0.6 - 1.0 m is normally required. For plants with PE > 10 000, where balancing tank is used, minimum one (1) unit of balancing tank shall be provided. The design flow of the upstream and downstream unit processes are recommended as follow: i) Where no balancing tanks is provided, design flow of unit process at Upstream = Peak/pumped flow Downstream = Peak/pumped flow ii) Where balancing tank is provided, design flow of unit process at Upstream = Peak/pumped flow Downstream = Average flow
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Requirements for Individual Treatment Processes
Table 5.10 Design Parameters for Balancing Tanks Description
m
Mixing power requirements Aeration
W/m3 of sewage
Overflow bypass to downstream unit requirement
5.7
Unit
Volume of tanks
3
Design Criteria
1.5 hr detention at Qpeak 5 at TWL
m3 air/hour/ m3 sewage
1 m3 of air supply for every m3 of sewage stored per hour at TWL
-
Yes
Design of Primary Sedimentation Stage At primary sedimentation stage, the velocity of sewage is reduced to subside settleable suspended organic matters in the sewage. The settled matter is known as primary sludge.
5.7.1
Purposes The purposes of primary sedimentation are: a) b) c)
5.7.2
to remove maximum amount of pollutants such as settleable solids quickly and economically.
to separate sewage into sludge and settled sewage, which by being treated separately are normally dealt with more efficiently and economically. When used as a preliminary step for further treatment, the main function of primary sedimentation tank is to reduce the organic loadings on the secondary treatment units and is a essential component of secondary sewage treatment.
Design Requirements The design requirements of primary sedimentation include the followings: a)
b)
106
Provide sufficient time for maximum settling under quiescent conditions. Therefore, design factors require careful consideration include: overflow rate, detention period, weir-loading rate, shape and dimensions of the basin, inlet and outlet structures, and sludge removal system. Tanks can either be rectangular, circular or upward flow (square).
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Requirements for Individual Treatment Processes
c)
Provisions for the removal of sludge on a daily basis.
e)
V-notch weirs with baffle shall be provided at the outlet. Weirs shall be adjustable with notches 100 mm deep. Typical variation in water level shall be no more than 50 mm under all conditions.
d)
f) g)
h) i)
j)
Holding tanks for wasted sludge must be provided.
Multiple hopper are not permitted.
Scum skimming shall be provided to remove both floating materials and scum. These materials can be either discharged to biosolid holding tank or sand drying bed. They shall not be returned to the preliminary treatment units.
Flow distribution channel/ chamber shall be provided for flow isolation or equal flow distribution. Rectangular tank
i)
Sludge hopper shall have side slopes of 60° or more from horizontal with the sludge pump located in a pit at hopper invert level. The length of suction pipe shall be minimised. Provision for withdrawal pipe from the tanks shall be provided. ii) The capacity of hopper shall be equivalent to 2 hours detention time at Qpeak. iii) Additional water depth of minimum 400 mm should be provided above the hopper in the vertical side-wall section between the top of the hopper and the top water level. The side-wall height should not be less than 400 mm. iv) Equalise flow distribution across the inlet of the tank shall be achieved using a multi-port wall and baffles. Circular Tank i) ii)
(k)
Circular tanks shall be no more than 50 m in diameter and minimum water depth shall be 3.0 m. Circular tanks with more than 30 m diameter shall be provided with perimeter walkway for cleaning the weir and shall have appropriate drive system.
The floor slab of the sedimentation tank shall be of reinforced concrete type construct to gradient to enhance the sludge scraping effectiveness.
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Table 5.11 Design Parameters for Primary Sedimentation Description
Unit
Design Criteria
Sedimentation followed by secondary treatment hr Detention time at Qpeak Surface overflow rate at Qpeak - circular (maximum)
m /m /d 3
- rectangular (maximum) Weir loading at Qpeak
2 45
2
m /m /d m /m/d
45 150
m/hr
1.2 - 2.0
m
> 3:1 2.5 1 : 1 to 2.5 : 1
3
2
3
Upward flow rate at Qpeak
Sizing of rectangular tanks Length : Width Min water depth Width : Depth Sizing of circular tanks Min. side water depth Floor slope wall
m
5.8
Design of Biological Treatment Stage
5.8.1
Introduction
> 3.0 1:12
Biological treatment is the heart of the sewage treatment process. It is the processes where the dissolved and non- settleable organic material remaining in the sewage are removed by living organisms. For reasons of long term whole life economics, ease of operation and maintenance, consistent effluent standards and standardisation, the following types of biological treatment processes are recommended for use in Malaysia. Suspended Growth System a)
Conventional activated sludge (CAS) system
b)
Extended aeration (EA)/Oxidation Ditch (OD) System
c)
108
Sequencing Batch Reactor (SBR)/Intermittent Decant Extended Aeration (IDEA)
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Requirements for Individual Treatment Processes
Attached Growth System a) Rotating biological contactor (RBC) system b) Trickling filter (TF) System c) Hybrid System/Combination multistage design All plants must be strictly designed to meet DOE Standard A/Standard B requirements including, nitrification and denitrification to reduce ammonia and total nitrogen removal level that ensure compliance with the requirement stipulated in Section 3 earlier. Total phosphorus removal must also be taken into account for plants where treated effluent is to be discharged into stagnant water bodies. Mass balance calculation must be computed and submitted for all biological treatment system and other unit processes proposed for the STP. 5.8.2
Conventional Activated Sludge System (CAS)
5.8.2.1
General Description The conventional activated sludge process is one of the many versions of the activated sludge process. The activated sludge process is most suitably used where land is limited and expensive, and where large volumes must be treated economically, without creating nuisance to neighbours. The process involves the production of activated mass of microorganisms capable of stabilising sewage aerobically. This is achieved by introducing organic waste, produced from pre-treatment and primary treatment facilities, into reactors where suspended aerobic bacterial culture oxidises the organic matter into stable matters. These active bacteria cultures are commonly known as activated sludge. During the process, new bacteria cell are also produced.
5.8.2.2
Design Requirements for CAS For the design of conventional activated sludge system, the aeration tank shall be preceded with primary sedimentation system. An appropriate amount of the bacteria culture, known as activated sludge must be recycled to the upstream of the reactor while the remaining excess sludge must be removed at secondary sedimentation system. All conventional activated sludge system used at STPs for Class 3, Class 4 and at where requested by the Commission must be designed with anoxic zone to achieve a total nitrogen removal in order to comply with the requirements in Section 3 of this Guidelines, as well as to minimise potential rising sludge at secondary sedimentation system. The anoxic zone must be mixed without inducing dissolve oxygen. Sludge treatment and dewatering must be available on-site to handle the large quantity of unstable sludge generated.
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Table 5.12 Design Parameters for Conventional/ Activated Sludge System Description
Unit
Primary Sedimentation System
Minimum number of aeration tanks F/M ratio
Hydraulic retention time (HRT)
Oxygen requirements (for BOD and ammonia nitrogen removal) Mixed liquor suspended solids (MLSS)
Sludge yield
hrs
kgO2/kg substrate mg/l
kg sludge produced/kg BOD5 consumed
Sludge age #
day
Return activated sludge flow, QRAS
m3/d
Waste activated sludge, QWAS
Must be provided 2
Dissolved oxygen (DO) level in tank mg/l Aeration device rating
Design Criteria
m3/d
0.25 - 0.50
6 -16 (for system where only ammonia removal is require) 12 -16 (for plants require total nitrogen removal) 2.0
1500 -3000 Typical: 2500 1.0
Continuous, 24 hrs 0.8 - 1.0
5 - 10
Refer to equation below † 0/66 [ 4DYJ &X 0/66
Cu is underflow concentration
QRAS / QINFLOW
0.75-1.0
Mixed liquor suspended solids recirculation for denitrification purpose
4 – 6 of Qavg
RAS pump rating
hrs/day
24
Organic loading
kg BOD5/kg MLSS
0.25 - 0.5
W/ m3
20
Volumetric loading
Minimum mixing requirement
110
kg BOD5/m3.d
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0.3 - 0.6
Malaysian Sewerage Industry Guidelines
Requirements for Stages of Sewage Treatment Requirements for Individual Treatment Processes
Table 5.12 Design Parameters for Conventional Table 5.12Activated DesignSludge Parameters Conventional Systemfor (cont.) Activated Sludge System (continued) Description Description
Unit Unit
Tank dimension Tank dimension Water depth Water depth Length:Width Length:Width Max width width of of joined joined tank tank Max # Sludge Age =
†
m m
Design Criteria Design Criteria
m
3–5
m
<30
3:1
3–5 3:1
< 30
total solids in aeration tank excess sludge wasting / day + solids in effluent
ª VT u MLSS º « » Q avg u SSeff «¬ T sludge »¼ WAS = Cu
>
@
Where: vT = volume of reactor (m3) 3 MLSS = mixed liquor suspended solids (kg/m )
Tsludge Qavg SSeff Cu
= sludge age (days) = average flow (m3/day) = effluent suspended solids (kg/m3) = underflow concentration (kg/m3)
Refer Table D1 and D2 for aeration equipment duty / standby and also to Refer Table D1ofand forfor aeration equipment duty/standby and also to relevant clause MSD2 1228 more details. relevant clause of MS 1228 for more details. 5.8.3 5.8.3 5.8.3.1 5.8.3.1
Extended Aeration System (EA) Extended Aeration System (EA) General Discription General Discription The extended aeration process is similar to the conventional activated The extended is similar to the conventional sludge process aeration except thatprocess it operates in the endogenous respirationactivated phase of sludge process it operates in theloading endogenous respiration the growth curve,except which that requires a low organic and long aeration phase of the growth curve,high which requires a low organic loading and time. The system produces MLSS concentration, high RAS pumping rate and low sludge long aeration time. wastage. The system produces high MLSS concentration, high RAS pumping rate and low sludge wastage. The advantage of having long hydraulic retention times is that it allows the plantadvantage to operateofeffectively overhydraulic widely varying flow and is waste The having long retention times that loadings. it allows Secondary be designed to thevarying variations hydraulic the plant toclarifiers operate must effectively over widely flowin and waste loadings and high MLSS concentrations associated with this process. loadings. Secondary clarifiers must be designed to the variations in hydraulic loadings and high MLSS concentrations associated with this process.
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5.8.3.2
Design Requirements for EA EA plants shall be designed as either plug flow or completely mixed. Anoxic zone at the head of the reactor must be provided for denitrification. The anoxic zone must be mixed without inducing dissolved oxygen For Oxidation Ditches, the minimum velocity within the channel shall be sufficient to keep the activated sludge in suspension. The minimum velocity within the channel shall not be less than 0.3 m/s. The tank configuration and aeration and mixing devices shall promote unidirectional channel flow, so that the energy used for aeration is sufficient to provide mixing in a system with a relatively long hydraulic retention time. Table 5.13
Design Parameters for Extended Aeration
Description Minimum number of aeration tanks F/M ratio
Hydraulic retention time (HRT) Oxygen requirements(for BOD and ammonia nitrogen removal) Mixed liquor suspended solids (MLSS) Dissolved oxygen (DO) level in tank Sludge yield
Sludge age # Waste activated sludge flow, QWAS Return activated sludge flow, QRAS
RAS pump rating Recirculation ratio, QRAS/QINFLOW
Unit
18 - 24 2.0
mg/l
2500 - 5000 Typical: 3000 2.0
mg/l kg sludge produced/kg BOD5 consumed
day m3/d m3/d
24 0.5 - 1.0
Water depth Length:Width Max width of joined tank
m ratio m
3
Volume 4
> 20 Refer to equation †
Cu is underflow concentration
hours/day
W/m3
0.4 (at 24 hrs HRT) 0.6 (at 18 hrs HRT)
0/66 [ 4DYJ &X 0/66
kg BOD5/m .d
112
0.05 - 0.1
hrs kgO2/kgsubstrate
MLSS recycle ratio Volumetric loading
Minimum mixing requirement Tank dimension
2
Design Criteria
4 – 6 times of Qavg 0.1 - 0.4 20
3–5 3:1 < 60
Malaysian Sewerage Industry Guidelines
Requirements for Individual Treatment Requirements for Stages of SewageProcesses Treatment
Notes: #
Sludge Age =
Notes: #
Requirements for Stages of Sewage Treatment
total solids in aeration tank
excess sludge wasting/day + solids in effluen
Sludge Age =
total solids in aeration tank
†
ª VT u MLSS º « » Q avg u SSeff «¬ T sludge »¼ WAS = Cu
>
ª VT u MLSS º Where: « » > Q avg u SSeff @ † «¬ T sludge »¼ in effluen WAS = = volume+ofsolids reactor (m3) vT excess sludge wasting/day Cu MLSS = mixed liquor suspended solids (kg/m3) Tsludge = sludge age (days) Where: = average flow (m3/day) Qavg = volume of reactor (m3) vT SSeff = effluent suspended solids (kg/m3)3 MLSS = mixed liquor suspended solids (kg/m ) Cu = underflow concentration (kg/m3) Tsludge = sludge age (days) = average flow (m3/day) Qavg Refer Table D1 and D2 for aeration equipment duty / SSeff = effluent suspended solids (kg/m3) relevant clauseconcentration of MS 1228(kg/m for3more details. Cu = underflow )
@
standby and also to
Refer Table D1 and D2 for aeration equipment duty/standby and also to relevant clause of MS 1228 for more details.duty / standby and also to Refer Table D1 and D2 for aeration equipment relevant clause of MS 1228 for more details. Figure 5.11 – Fine Bubble Diffuse Air Extended Aeration System
Anoxic Zone Aeration Tank Flow Final Clarifier Figure 5.11 Fine Bubble Diffuse Air Extended Aeration System Distribution Grit Removal Diffuse Air Extended Aeration System Figure 5.11 – FineScreens, Bubble Raw Sewage Inlet
Anoxic Zone
Aeration Tank
Flow Distribution
Sewage Pump Station Screens, Grit Removal
Effluent To River
Final Clarifier Effluent To River
Return Sludge Pump Station
Raw Sewage Inlet Sewage Pump Station
Return Sludge Liquor Pump Station Chemical Dosing
Sludge Storage Area
Mechanical Sludge Dewatering Liquor Chemical Mechanical Sludge Thickener Dosing
Ultimate Disposal
Sludge Holding Tank Sludge Storage Area
Mechanical Sludge Dewatering Mechanical Sludge Thickener
Sludge Drying Bed
Sludge Holding Tank
Ultimate Disposal
OPTIONAL Sludge Drying Bed
OPTIONAL
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Requirements for Individual Treatment Processes Requirements for Individual Treatment Processes
Figure 5.12 Oxidation Ditch Activated Sludge System Figure 5.12 – Oxidation Ditch Activated Sludge System
M echanical R otor
Flow Distribution
S creens, G rit R em oval R aw S ewage Inlet
Final Clarifier
Flow M easurem ent
E ffluent To River
O xidation Ditch S ewage P um p S tation R eturn S ludge P um p S tation
Chem ical D osing
S ludge Storage A rea
M echanical S ludge Dewatering
M echanical Sludge Thickener
S ludge Holding Tank
Ultim ate D isposal S ludge D rying B ed
O P TIO N AL
5.8.4 5.8.4
Rotating Biological BiologicalContactors Contactors (RBC) Rotating (RBC)
5.8.4.1 5.8.4.1
General Description Description General Rotatingbiological biological contactors series of media rotating media for Rotating contactors use a use seriesa of rotating for biological biological treatment. The rotating medium, typically made from sheets treatment. The rotating medium, typically made from sheets of high quality of highprovides quality aplastic, surface on which organisms grow. plastic, surface provides on which aorganisms grow. As the media rotate, As the media rotate, the fixed film biomass is in contact with organic the fixed film biomass is in contact with organic pollutions in sewage and pollutions in sewage alternately. and oxygenLayers in atmosphere oxygen in atmosphere of biomassalternately. are sheared Layers from theof biomassofare from the the rotation surface to of prevent the media during of thetherotation surface thesheared media during overgrown fixed film. to prevent overgrown of the fixed film. RBCs RBCs are are conventionally conventionally submerged submergedtoto40% 40%ofof disc discdiameter. diameter. Increased Increased submergence 90% is also acceptable if sufficient air submergence ofofdiscs discsupuptotoabout about 90% is also acceptable if sufficient supply is provided at the base of the tank. This system is normally called air supply is provided at the base of the tank. This system is normally the submerged biologicalbiological contactor contactor (SBC). called the submerged (SBC).
5.8.4.2 5.8.4.2
Design RBC Plants Design Requirements Requirementsforfor RBC Plants Preceding Preceding the the RBC RBC must must be be aa primary primary sedimentation sedimentationtank tankororaa secondary secondary screening with <6 mm opening. A flow balancing tank must also be screening with < 6 mm opening. A flow balancing tank must also be provided unless the plant is designed to peak flow. provided unless the plant is designed to peak flow. Units must be covered for aesthetics and odour control, and only approved Units must for aesthetics and odour control, and only approved media typesbe arecovered accepted. media types are accepted.
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Table 5.14 Design Parameters for RBC Plants Table 5.14 Design Parameters for RBC Plants Description Description Minimum number of stages
Unit
3
Unit
Total BOD specific loading g/m /d Minimum number of stages 5
5 - 10 3
2
Total BOD5 specific loading Total tank volume
Design Criteria Design Criteria
5 -210 Based on hrs at Qavg
g/m2/d
0.9 kg excess sludge/ Based on 2 hrs at Qavg kg BOD5 consumed Sludge yield kg excess sludge/ 0.9 Disc diameter m kg BOD5 consumed 2.5 - 3.5 Speed of rotation rev / min 0.5 - 1.0 Disc diameter M 2.5 - 3.5 Maximum peripheral velocity m/s 0.3 Speed of rotation rev / min 0.5 - 1.0 Depth of disc submergence % 40 - 90 Maximum peripheral velocity m/s 0.3
Sludge yield Total tank volume
Depth of disc submergence
%
40 - 90
Refer also to Table D.3 for duty standby requirements and relevant clause of MS 1228 Refer alsofor to more Table details. D.3 for duty standby requirements and relevant clause of MS 1228 for more details. Figure 5.13 Rotating Biological Contactor (RBC) Systems Figure 5.13 – Rotating Biological Contactor (RBC) Systems Rotating Biological Contactor Screens, Grit Removal, Flow Measurement
Fine Screen
Raw Sewage Inlet
Flow Distribution
Final Clarifier
Balancing Tank Sewage Pumping Station
Effluent To River
Liquor Chemical Dosing
Sludge Storage Area
Mechanical Sludge Dewatering Mechanical Sludge Thickener
Sludge Holding Tank
Ultimate Disposal SludgeDrying Bed
OPTIONAL
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5.8.5 Trickling Filter 5.8.5 Trickling Filter 5.8.5.1 General Description 5.8.5.1 General Description The trickling filter is an established biological treatment process removing 65 to 85% and suspended solids.treatment The process of a bed The trickling filterBOD is an5 established biological processconsists removing 65 to 85% BOD and suspended solids. The process consists of a bed of of highly 5permeable medium. An overhead rotating distributor applies highlysewage permeable An The overhead to medium. the media. flowrotating tricklesdistributor over andapplies flows sewage downward to to the the media. The flow trickles over and flows downward to the underdrain underdrain system. system. The media provides a large surface area to develop biological slime The media provides to developfilm. biological slimecontains growth living growth whichaislarge alsosurface knownarea as zoogleal The film which organisms is also known as zoogleal film. The film contains living organisms that break down organic material in the sewage. that break down organic material in the sewage. Many variations of the trickling filters have been constructed, however Many the variations of the trickling have been constructed, recommended designsfilters are given in Table 5.15. however the recommended designs are given in Table 5.15.
5.8.5.1 Design Requirements for Trickling Filters 5.8.5.1 Design Requirements for Trickling Filters Secondary (
Biofilter Pump Station
Fine Screen
Screens, Grit Removal
Flow Distribution Final Clarifier
Filter
Raw Sewage Inlet
Effluent To River
Sewage Pump Station Liquor
Chemical Dosing
Sludge Storage Area
Mechanical Sludge Dewatering Mechanical Sludge Thickener
Sludge Holding Tank
Ultimate Disposal
Sludge Drying Bed
OPTIONAL
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Table 5.15 Design Parameters for Trickling Filter Description
Unit
Organic loading
Design Criteria
kg BOD5/day/m3
(depending on filter type) Low rate Intermediate rate High rate
0.08 - 0.15 0.15 - 0.5 0.5 - 2.0
> 1.0
Recirculation of flow to head of plant Qrecycle Qinflow
(to maintain wetting rate and improve flow) Acceptable media
Hydraulic loading
m3/day/m2
Sludge Yields
kg sludge / kg BOD5 influent
Minimum depth of media
m
Low rate Intermediate rate High rate
Low-rate filters Intermediate filters High-rate filters
HDPE, PVC, stone, slag, coke, etc. (random or standard arrangement) 1-4 4 - 10 10 - 40 0.5 0.6 - 0.8 1.0
1.5
Refer also to Table D.4 for duty standby requirements and relevant clause MS 1228 for more details. 5.8.6
Sequencing Batch Reactors (SBR) System
5.8.6.1
General Description Sequencing Batch Reactors system is suspended activated sludge system. In this system, sewage flows into one or more reactors where biological oxidation and clarification of sewage take place within the same reactors sequentially on cyclical mode. There are five (5) basic sequences in a cycle, namely:
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1.
Fill
3.
Settle
2. 4. 5.
React (Aeration) Decant Idle
Typically, all actions in the reactor occur at different sequence of time. In other words, the system is intermittently fill and intermittently decant. Typical SBR plant consists of a minimum of two (2) reactors in a plant. When one unit of the reactors is in fill mode, the other reactor(s) may be in the stage of react, settle, decant or idle. Recent development of SBR system leads to the emergence of variation in the operating sequences. Continuous fill and intermittently decant system is one of the variations of this system, where feeding into all rectors are continuous but the other phases (react, settle, decant, idle) are run in sequence. In the reaction stage, oxygen supplied to the system shall be in accordance to the load to the system within the time frame of reaction cycle. This generally requires higher oxygen capacity per unit time than a continuously aerate system. In the decant stage, there shall be sufficient time to allow for mixed liquor suspended solids (MLSS) to settle before effluent decanting begins. Decanting time is normally much shorter than fill time. Consequently, the effluent flow rate will also be much higher than influent flow rate. Hence the design of the decanting weir must be capable to handle high over-flow rate without scouring the settled sludge. Therefore, sufficient clear water depth between the minimum water level after decant and the top of the settled sludge blanket must be allowed for to minimise sludge carry over. Hence the depth of water decanted must be restricted to prevent scouring of solids. 5.8.6.2
Design Requirements for SBR Plants All SBR plants must be designed to cater for peak flows. A minimum of a two (2) tanks system is required. Proven control system in the form of Programmable Logic Controller (PLC) with complete instruction, and operational and training manuals must be submitted together with the design. All SBR systems must be preceded with complete preliminary works. Allowance shall be provided to completely empty a tank for maintenance purposes without interrupting the operating sequence of the plant. Table 5.16 highlights the key design requirements for an SBR plant.
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Table 5.16 Design Requirements for SBR System Unit
Continuous Fill and Intermittently Decant
Intermittently Fill and Intermittently Decant
unit
Minimum 2
Minimum 2
Hydraulic retention time at Qavg (at average water level)
hr
18 – 24
18 – 24
F/M ratio
d-1
0.05 – 0.08
0.05 – 0.30
Sludge age
d
20 – 30
10 – 30
kg Sludge
0.75 – 0.85
0.75 – 1.10
mg/l
3000 – 4500
3000 – 4500
hr
4–8
4–8
DO (Reactor)
mg/l
0 ~ 6.5
0 ~ 6.5
DO (Effluent)
mg/l
2.0
2.0
Parameter No. of Reactors
Sludge Yield
kg BOD5 load
MLSS (End of decant) Cycle Time
Oxygen Requirement
kg O2 kg Substrate
Cycle time Aeration Time
x
2.0 kg O2 kg substrate
Cycle time Aeration Time
x
2.0 kg O2 kg substrate
Decant time
hrs
≥ 1.0
≥ 1.0
Decant depth
m
Max 0.5
max 1.0
Decant volume
%
Not more than 25% of volume of Biological Reactor at TWL
Not more than 30% of volume of Biological Reactor at TWL
m3/m/hr
≤ 20 for decant draw-down from TWL
≤ 20 for decant draw-down from TWL
2 nos. independent decanter per tank
2 nos. independent decanter per tank
4.0
4.0
Decanting device loading rate* Minimum number of decanter Max. pecanter length WAS
kg sludge/d
Fill volume
* * †
m
m3
Total solids in system Total solids in system Was= Was= Slude age Slude age Vfill = (QP m3/hr x 1.5hr) + (Tfill –1.5) x QAVG (if no balancing tank) Vfill = QAVG x Tfill (if preceded by balancing tank)
Vfill = (QP m3/hr x 1.5hr) + (Tfill –1.5) x QAVG (if no EQ) Vfill = QAVG x Tfill (if preceded by balancing tank)
For continuous fill, length to width ratio shall be based on 3 : 1 Decanting device loading rate shall be based on Vfill/decant time during decanting. RAS maybe necessary where length to width ratio poses dilution affect into the inlet.
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5.8.7
Design Requirements for Hybrid Systems A hybrid system is a recent development in biological treatment combining suspended solids and fixed film growth processes. The treatment system may be considered if the design criterion to be adopted has proven performance and result.
5.8.8
Design for Nutrient Removal for Sensitive Receiving Water Nutrient removal is required for effluent discharge to lakes and stagnant water bodies to prevent eutrophication or other potential impacts that may impede the sensitivity of the receiving water. Nutrient removal can be achieved via: a)
Biological treatment.
c)
Chemical treatment.
b)
Physical treatment.
It has been emphasised in the beginning of this chapter, all biological treatment system shall be designed to achieve ammonia reduction and where necessary anoxic zone/stage to be added to encourage denitrification for total nitrogen removal. The biological phosphorus removal mechanism is based on the fact that bacteria are capable of storing excess phosphorus as polyphosphate and removing simple fermentation substrates produced in the anaerobic zone and assimilating them into storage products within their cells. Hence, the design for of the biological treatment shall follow the following for plants where nutrient removal (nitrogen and phosphorus) is required, design parameters: Table 5.17 Design Requirement for Biological Nutrient Removal System Item
120
Design Parameters
HRT (hrs)
MLSS (mg/l)
1 2
1st stage anaerobic 1st stage anoxic
1-2 2-4
2 000 – 6 000 2 000 – 6 000
3
1st stage aerobic (oxic)
8 - 12
2 000 – 6 000
4 5 6
2nd stage anoxic 2nd stage anaerobic 2nd stage aerobic (oxic)
2-4 1-2 4
2 000 – 6 000 2 000 – 6 000 2 000 – 6 000
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RAS from clarifier 2 to 1 (MLSS recirculation ratio) 3 to 2 (MLSS recirculation ratio) Mixing Mixing Malaysian Sewerage Industry Guidelines
Requirements for Individual Treatment Processes Requirements for Stages of Sewage Treatment
It has been emphasised in the beginning of this chapter, all biological It has been emphasised in be the designed beginningtoofachieve this chapter, all reduction biological and treatment system shall ammonia treatment shallanoxic be designed to achieve ammonia reduction and where wheresystem necessary zone/ stage to be added to encourage denitrification necessary anoxic zone/stage to be added to encourage denitrification for for total nitrogen removal. total nitrogen removal. Figure 5.15 Typical Process Flow Diagram for Figure 5.15 - Typical Process Flow Diagram Biological Nutrient Removal System for Biological Nutrient Removal System
To get phosphate
To get nitrate bac k
Back
Q
1st. Anaerobic
1st. Anoxic
1st. Aerobic
2nd Anoxic
2nd. 2nd. Anaerobic Aerobic
Clarifier
Effluent
RAS
Alternatively, both both physical and chemical treatment may be used Alternatively, physical and chemical treatment maytoberemove used to Phosphorus wastewater.in wastewater. remove in phosphorus TheThe designer shallshall taketake all necessary consideration in theindesign in relation designer all necessary consideration the design in relation to the specific requirements of the receiving water in determining the actual to the specific requirements of the receiving water in determining the nutrient removal requirement the case byon case actual nutrient removal on requirement thebasis. case by case basis.
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5.9
Design of Secondary Clarifiers
5.9.1
Purpose Effluent from biological processes contains large populations of microorganisms (MLSS). Secondary clarifiers provided after the biological system allow the mixed liquor organisms/ solid to settle. Clear supernatant is discharged as the effluent, while some of the settled microorganisms are returned to the biological treatment system to maintain the MLSS concentration and excess microorganisms are removed as biosolid to the sludge treatment facility.
5.9.2
Design Requirements The design requirements shall include: I) a)
Minimum retention time for settlement.
c)
Sludge hopper to collect settled sludge.
b) d)
e)
f)
g)
Maximum settling velocity for settlement. All clarifiers must be equipped with sludge scrapers to skim sludge from the bottom unless they are designed with a 60o hopper bottom.
All clarifiers must be equipped with scum skimmer to remove scum from the surface. The scum collected must be drained (where necessary) and disposed off. Returning the scum to the preliminary system or the biological system is not permitted. Multiple hopper are not permitted.
Stilling basin to prevent hydraulic shock circuiting.
h)
Bottom slope at clarifier floor.
j)
Appropriate feed and outlet pipe with hydraulic consideration.
i)
k) l)
m) II) a)
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General
Facilities to dispose scum and sludge.
Effluent collection channel to be of glazed finish/tiles. Proper maintenance access to all components.
Properly designed air lift pumps are only permitted for PE less than 1000.
Weirs If insufficient length is available, then considerations shall be given for the use of double weir. Volume 4
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b)
Cascading V-notch is preferred over rectangular weirs.
d)
Broad crested weirs are not encouraged.
c)
e) f)
Slots in the weir shall be provided to allow for level adjustment during the installation stage. All parts of the weirs must be visible and accessible for regular cleaning. Type of weir and the hydraulic calculation for the weir proposed must be submitted.
III)
Circular clarifiers
a)
The maximum diameter permissible is 50 m and a reasonable allowance between tanks shall be provided for vehicle access.
b) c) d)
The minimum side water depth shall be 3.0 m. Greater side water depths may be used if it can be shown that the mixed liquor is well denitrified in the aeration tank. Flow distribution channel/chamber shall be provided for flow isolation or equalise flow distribution.
The scraper tip travelling speed shall not exceed 0.03 rpm. A multiple stage reduction unit must be incorporated to achieve such speed.
IV)
Rectangular clarifiers
b)
Multiport wall and baffled inlet shall be provided.
d)
Allowance also shall be provided for vehicle movement between unit processes for maintenance purposes.
a)
c)
e)
Shall not be wider than 6 m per tank to allow for scraper removal, unless other approved scraper units are available.
Slide gates shall be used to isolate each tank.
Scraper travelling speed shall be between 0.3 – 0.6 m/min.
Refer also to relevant clause of MS 1228 for more details. 5.9.3
Multiple Hoppers Multiple hoppers are not accepted. This is due to the settling characteristics of the particles in the flow. Larger and heavier particles settle faster than smaller and lighter particles, creating difference in the distribution of sedimentation in different hoppers. This will present operational difficulties because sludge removal from the hoppers is unequal. To avoid the non-uniform withdrawal of sludge, each hopper in the multiple hopper configuration needs a separate pipe and pump or valve on each outlet.
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Table 5.18
Design Parameters for Secondary Clarifiers
Description
Design Criteria
Unit
PE ≤ 5,000
PE > 5,000
Minimum number of tanks
2*
2
Tank configuration
Square Circular Rectangular
Circular Rectangular #
Minimum side water depth
m
3**
3
Minimum hydraulic retention time (HRT) at Qpeak
hrs
2
2
Surface overflow rate at Qpeak
m3/d/m2
≤30
≤30
Solids loading rate at Qpeak
kg/d/m2
<150
<150
Solids loading rate at Qavg
kg/d/m2
<50
<50
Weir loading rate at Qpeak
m3/day/m
<180
<180
Return activated sludge (RAS) pumping rate
Continuous
Continuous
Waste activated sludge (WAS) pumping rate
Continuous or batch
Continuous or batch
Sizing of rectangular tanks Length : Width Maximum side water depth
3:1 or greater. m
Width : Depth
3.0 1 : 1 to 2.5 : 1
Sizing of circular tanks Side water depth, minimum
m
Floor slope wall
3.0 ** 1:12
Notes: * For PE less than or equal to 1000 a single clarifier is acceptable. # Rectangular tanks are acceptable if equipped with automatic scraping and desludging devices. ** For square clarifier with 600 slope minimum 1 m side water depth shall be provided.
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5.10
Disinfection Disinfection refers to the selective destruction of disease causing organisms in sewage effluent. Methods of disinfection can be physical, chemical or radiation. Continuous disinfection is required for those areas where the discharge from the sewage works will cause detrimental effect onto the receiving water course, such as bathing beaches, lakes, etc. The Commission reserves the right to determine the need for the provision of a continuous disinfection facility. The common forms of disinfection that are available for wastewater applications are: a) Chlorination b) Ultra-violet (UV) c) Others Chlorination is by far the most common type of disinfection used worldwide. This is due to its effectiveness in providing a good pathogen kill with relative simplicity in operation and maintenance. However, chlorination using chlorine gas, requires a higher degree of operational skills and poses potential health and safety hazards in the shipping and handling aspects. Therefore, to reduce these hazards, only liquid or solid hypochlorite (sodium or calcium) shall be used. Ultra-violet (UV) disinfection differs from chemical disinfection in that it uses irradiation to induce photobiochemical changes within the micro-organisms. To ensure effective photochemical reaction taking place, one of the conditions is that such radiation must be absorbed by the target molecule (organism). The other condition is that sufficient radiation energy to alter chemical bonds is made available. Given the conditions above, it is critical that the effluent prior to disinfection must be relatively clear of suspended solids. As such, for UV disinfection to be highly effective in wastewater applications, filtration of upstream of the UV unit must be made available. Other forms of wastewater disinfection that are available are maturation ponds and ozonation. Maturation ponds have been used widely and successfully in Malaysia. However, the drawback is that a relatively large area of land is required to provide sufficient retention time in the pond for the decay of pathogens. Ozone disinfection involves the direct ozone oxidation or by reaction with the radical by-products of ozone decomposition. However, due to ozonation’s relatively new status in wastewater applications and higher costs at small scale facilities, its usage for disinfection is still limited.
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5.10.1 5.10.1
Design Requirements Requirements Design All new STPs must have provision for disinfection infrastructure such All new STPs provision for structures. disinfection infrastructure as contact tankmust andhave other necessary The provisionsuch of as the contact tankfacilities and other The provision of 5.19 the disinfection and necessary equipmentstructures. shall be in accordance to Table disinfection facilities andshall equipment shallout be in in continuous accordance or to intermittent Table 5.19 below. The disinfection be carried below. mode. The disinfection shall be carried out in continuous or intermittent mode. Table 5.19: Requirements for Disinfection Facility Table 5.19: Requirements for Disinfection Facility Description Description Class of STP*
Continuous Continuous Class 4
Class of STP*
Intermittent Intermittent Class 1 Class1 2 Class
Class 4
Class2 3 Class
Type of Disinfection
Chlorination Chlorination Class 3 Ultra-violet (UV) Type of Disinfection Chlorination Chlorination Ozone Ultra-Violet (UV) Facility (1duty/1standby) for Basic facility structure. equipment Ozone (1Duty/1Standby) for requirements Basic facility *Facility The Commission may impose separate on case by case equipment structure. basis.
* The Commission may impose separateofrequirements case by case basis. Figure 5.16 Schematic illustration ultravioletondisinfection system with stilling plate for flow conditioning and Figure 5.16 – Schematic illustration ultraviolet disinfection system with elongated weiroffor level control stilling plate for flow conditioning and elongated weir for level control "A"
"A" FLOW
PDC
COVER PLATES OR GRATING
STAINLESS STEEL WEIR
TOP VIEW (Cables removed for Clarity)
CONTROL PANEL AND POWER DISTRIBUTION CENTRE
FRONT ACCESS
ULTRAVIOLET LAMP RACKS COVER PLATES OR GRATING STILING PLATES
LEVEL PROBE
FLOW
SECTION 'A' - 'A'
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5.17 schematic Profile schematic of lamp relative modules relative Figure Figure 5.17 – Profile of lamp modules to inlet and outlet to inlet and outlet structure structure Figure 5.17 – Profile schematic of lamp modules relative to inlet and outlet structure Flapper Gate Level Control
Disinfection Module Power & Data Interconnect Cables
Flapper Gate Level Control
Flow
Power & Data Interconnect Cables
Effluent Channel
A
UV Protective
Disinfection Module
Effluent Channel
Station Cleaning Liner with covet 304 Stainless Steel Station Cleaning Liner with covet 304 Stainless Steel
A
Service Electrically Operated Area Jib Host
Station Cleaning drain
Electrically Operated Jib Host
A
Inffluent Channel Flow
Service Area
A
UV Protective
Inffluent Channel Flow Flow
Power Distribution Data center (PDDC)
Power Cable Signal Cable from Plant Flow meter
Station Cleaning drain
PLAN VIEW
Power Distribution Data center (PDDC)
Power Cable Signal Cable from Plant Flow meter
PLAN VIEW
Influent Channel Influent Channel
Influent Channel
Influent Channel
SECTION "A - A" SECTION "A - A"
Figure 5.18 Chemical-feed system schematic Figure 5.18 Chemical-feed system schematic Figure 5.18 Chemical-feed system schematic
CALIBRATION COLUMN
RELIEF VALVE
CALIBRATION COLUMN
RELIEF VALVE
CHEMICAL FEED PUMP CHEMICAL FEED PUMP
STORAGE TANK
BACK PRESSURE CONTROL BACK PRESSURE CONTROL
STORAGE TANK
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5.10.1.1 Continuous Disinfection I)
Disinfection with Ultra-Violet (UV) a) b)
c) d)
e) f)
g) h)
i)
j)
128
Filtration ahead of the ultra-violet disinfection is a must in order to ensure consistent and reliable disinfecting performance, as well as, to reduce maintenance, such as, fouling of the UV lamps.
The performance of the UV unit shall meet a UV transmittance level of secondary effluent of at least 60% on a filtered basis. If a lower transmittance level is encountered, it shall be compensated with the reduction in the spacing of lamps and/or usage of an advanced higher intensity system to compensate the lower tranmissibility of the sewage effluent. The channel for the UV shall be open, long and narrow to encourage plug flow and avoid short circuiting.
As a guide, the average sizing is roughly 10 conventional 1.5 meter lamps per 1,000 m3/day at peak flow. However, the actual sizing shall be site specific and subjected to effluent quality desired as well as the level of upstream treatment provided.
In the design to house the UV modules, it is important to include proper inlet and outlet structures and consider the approach and exit flow conditions.
A stilling well is required to distribute the flows and equalise the velocities across the cross-section of the channel. The stilling plate shall be placed at least 5 meters in front of the first lamp bank. Otherwise, the channel should have an undisturbed straight line of two (2) or three (3) lamps length.
Sufficient distance shall be allowed between lamp banks (0.5 m to 1.0 m) and two (2) to three (3) lamp lengths between the last bank and the downstream level control device.
In large system applications, a multichannel configuration is required. This is to allow the inlet structure to satisfy the dual requirements of inducing flow and to allow even distribution of flow among operational channels. Channel inlet structures shall allow for hydraulic isolation of individual channels during low flow and routine maintenance. In operation, the multichannel design shall be controlled to maintain a minimum velocity through any one channel. Wastewater within the channel must be maintained at a constant level with little fluctuations. This shall be accomplished by using a mechanical counter balance gate downstream of the lamp batteries.
It is crucial to avoid a dryness state in the channel during low or no flow conditions to prevent the fouling of the quartz jackets
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surrounding the lamps and/or causing damage to the UV modules. To alleviate this, for a small STP, a fixed or adjustable weir should be used.
k)
l)
m)
n)
However, sufficient weir length shall be provided to avoid water level fluctuations. In larger STPs using the multichannel design, these flow fluctuations can be attenuated by the opening and closing of channels as needed. Control systems should be simple. Its objective is to ensure that the system loading can be maintained and disinfection accomplished, while conserving the operating life of the lamps. In small STPs, the control system shall consists, of a full duty unit in operation at all times with a similar redundant unit on standby. Manual control and flexibility should be made available to enable the operator to bring portions of the systems in and out of operation, as needed, to adjust for the changes in flow or water quality. In larger STPs, a complete automation is warranted for plants using the multi channel design.
Safety aspects of an UV disinfection facility involve mainly the electrical hazards and protection from the exposure to UV radiation. The exposure risks could be minimised as long as the operating lamps are submerged and the lamp batteries are shielded. The UV lamps shall not be operated in air and unshielded. All systems must be equipped with safety interlocks that shut down the modules if they are moved out of their operating positions or the wastewater level falls, leaving any or all lamps exposed to air. Electrical hazards can be minimised by the inclusion of ground-fault-interruption circuitry with each module. This feature is a requirement for all UV systems. The design of the UV system shall allow for easy access to the lamp modules for cleaning and other maintenance tasks. The installation shall have adequate working area for maintenance and servicing of the modules when taken out of the channels. Cleaning of the lamps shall be accomplished using mechanical wipers which may be fitted with chemical injectors and with chemical baths when taken out of the channels. A drainage system back to the head of the treatment works shall be provided to drain back water from the reactors, channels and other related tankage. In addition, a permanent clean-water system is to be made available to allow for rinsing and cleaning needs. A bypass around the UV disinfection facility is to be made available in the event the system is shut down completely for maintenance.
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Table 5.20 Design Guides for Disinfection with Ultra-Violet(UV)
UV system
Description
Design Criteria
Mounted in open channel type* Must be preceeded with filtration.
Minimum UV Dose (at 254 nm) at end of lamp life
30 mJ/cm2 (30,000 µWs/cm2) at Qpeak
Maximum Total Suspended Solids in effluent to UV system
< 10 mg/l
Maximum Mean Particle Size in effluent
20 microns
UV Transmittance at 254 nm
65%
Lamp life
≥ 12 000 hours
Minimum UV output at end of lamp life
80%
Operating Temperature
18 – 40 oC
Relative Humidity
> 95% at 40 oC
UV detection System
UV sensor, transmittance, dose pacing
Lamp Sleeve Cleaning system
a. Mechanical wipers and out of channel chemical cleaning. b. Additional 25% more lamps shall be provided for mechanical wipers.
Standby lamps
25% to be provided with min 2 lamp banks
Disinfection Standards
In accordance with receiving water requirement or effluent usage
Note:
*Enclosed system shall be permitted under special circumstances
II)
Disinfection with Hypochlorite a)
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Calcium and sodium hypochlorite are hazardous chemicals to handle and use. Calcium hypochlorite is classified as a corrosive Volume 4
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and rapid oxidant, while sodium hypochlorite is a corrosive agent. Eye protection, access to an emergency eyewash system and showers must be made available to the operators.
b)
c)
d)
e)
f)
g)
h)
Also, direct contact with the undiluted hypochlorite is likely to cause burns to the skin and clothing. Therefore, it is imperative that protective clothing which includes rubber gloves, must be worn by operators when working with these chemicals. When calcium hypochlorite is being transported in the powder form and mixed in water to form solutions, the operator should always wear eye protection and dust masks. All areas exposed to hypochlorite should be washed thoroughly. Chlorine dosage ranges from 6 to 10 mg/l for effluent. The dosage rate is affected by the suspended solids and ammonia present in the effluent, mixing employed, contact time and the control strategies used for dosing. Proper mixing is important for effective disinfection.
If a hydraulic jump is employed as a mixing device, the submergence of the diffuser shall not be less than 230 mm (9 in.) below the water surface and placed before the hydraulic jump at the minimum flow. The hydraulic jump is effective in mixing when the head loss exceeds 0.6 m (2 ft). To ensure adequate mixing is achieved, the evaluation of the flow characteristics should be carried out. As a minimum, the Reynolds number shall be 2.1 x 104 for pipe flow and Froude numbers between 4.5 and 9 for open channels is recommended.
Hypochlorinators are chemical-feed pumps used for feeding sodium or calcium hypochlorite. The basic components are a storage reservoir or mixing tank for the hypochlorite solution; a metering pump that consists of a positive displacement pumping mechanism, motor or solenoid and a feed rate adjustment device; and an injection device. Depending on the size of the system, a plastic or fiber-glass vessel may be used to hold a low-strength hypochlorite solution. It is not acceptable to use metals commonly used in the construction of storage tanks to hold the hypochlorite solutions because of the corrosive nature of the chemical which will also expedite the decomposition of the liquid hypochlorite.
Feeding of calcium hypochlorite will require a mixing device, usually a motorised propeller or agitator located in the tank. Also, in the tank is a foot-valve and suction strainer connected to the suction inlet of the hypochlorinator.
The hypochlorinator shall be feed rate adjustable.
The injection fitting shall be similar to that used in the gas chlorinator.
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i)
A chlorine contact tank shall take the form of rectangular serpentine chamber. Circular chambers for disinfection are not acceptable.
j)
Local supply of water shall be made available for the dilution of powder calcium or sodium hypochlorite. A breaker tank for supply of water is required for the proper running of the hypochlorinator. If deemed necessary, the water pressure maybe increased with the provision of water booster pump.
k)
Pipe works should be suitable for chlorination applications and well supported.
l)
m)
n) o)
Provision for draining the chlorine contact chamber is required for cleaning and maintenance purposes. This shall include a drain valve located at the bottom of the downstream end of the chamber. The point of discharge shall ensure that adequate treatment is given and this could be done through pumping the content from the chamber and return to the head of the treatment plant. A bypass around the chlorine contact chamber shall also be provided to enable flows to be bypassed during maintenance or servicing. There shall be penstocks upstream and downstream of the chlorine contact chamber for isolation purposes.
Adequate access with sufficient turning radius for the vehicle to carry in the chemicals to the disinfection system shall be provided.
A small housing structure shall be provided to house hypochlorinator, associated chemicals and ancillaries. Some important consideration have to be given in the design of adequate space for the operators to replace and fill the chemicals, washing facility, eyewash, record keeping of chemical dosing, effluent flowmeter data among others. Due to the hazardous nature of the disinfection system housed, a locking system shall be made available to deter vandalism and promote safety of the plant.
The structure housing the hypochlorinator and the chemicals shall be bunded to prevent the possibility of spillage. The sizing of bunds shall correspond to the total volume of the storage/solution tanks.
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Table 5.21 - Design Guide for Disinfection with Hypochlorite Type
Dosage Mixing Hypochlorinator system Equipment Contact Tank Contact Period
Maximum depth Depth : Width Min no. of passes Length : Width at each pass Wetted Depth : Width
Calcium or Sodium
6 – 10 mg/l Mechanical, baffles or hydraulic jump. Feed rate adjustable 1 duty/ 1 standby 15 minutes at Qpeak 3m 2:1 4 6:1
< 2:1
5.10.1.2 Intermittent Disinfection The design requirements for intermittent disinfection facility shall comply to the following: a) b)
Due to the infrequent usage and other health and safety considerations in an intermittent disinfection system, ONLY liquid hypochlorite, either calcium or sodium, shall be used. A chlorine contact chamber shall be provided with a minimum of 15 minutes hydraulic retention time at peakflow. This chamber shall be of a rectangular configuration with aspect ratios optimised to promote plug flow conditions. The recommended aspect ratios are as follows: i) ii) iii) iv)
Sewage Treatment Plants
Length to width (each “Pass”): 6:1 Minimum number of passes: 4 Height to width of the cross-section of the wetted section: < 2:1 Depth of chlorine contact chamber is typically 2 – 3 m. The corners shall be rounded to reduce the dead flow areas and the velocity through the contact chamber shall be sufficient to minimise solids deposition.
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v)
horizontal baffles shall be used to ensure the plug flow conditions are maintained and to minimise the possibility of short circuiting.
vi)
Upstream of the contact chamber, a dosing coupling for easy hook-up of the mobile hypochlorite disinfection system shall be an inherent part of the chamber design.
c)
A breaker tank for supply of water adjacent to the contact tank is required to provide water for the mixing of powder hypochlorite and for cleaning or cleansing of the contact chamber. If deemed necessary, a water booster system shall be provided to increase the water pressure for the intended application.
d)
Draining provision must be made available to allow for complete drainage of the chlorine contact tank. For this purpose, a drain valve shall be provided at the bottom of the downstream end of the chamber.
e)
f)
g)
Penstock/slide gate shall be provided at the upstream and downstream end of the contact chamber. This allows for the effluent flow from the treatment plant to bypass this chamber when its service is not required.
Adequate access shall be provided for a portable hypochlorinator unit mounted on a skid to be brought by a truck to the contact chamber area when disinfection is required. A concrete pad adjacent to the contact chamber shall be provided for the skid mounted hypochlorinator to be situated when in use. Power supply shall be adequately provided and located close to the contact chamber to run the intermittent disinfection system. Table 5.22 Design Guide for Intermittent Disinfection Type
134
Calcium or Sodium
Dosage
6 – 10 mg/l
Mixing
Mechanical, baffles or hydraulic jump.
Hypochlorinator system
Feed rate adjustable
Equipment
1 duty/ 1 standby
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Table 5.22 Design Guide for Intermittent Disinfection (cont.) Type
Calcium or Sodium
Contact Tank Contact Period
15 minutes at Qpeak
Maximum depth Depth : Width Min no. of passes Length : Width at each pass Wetted Depth : Width
3m 2:1 4 6:1 < 2:1
5.11
Design of Flow Measurement Devices
5.11.1
Purpose of Flow Measuring Devices Flow measuring devices are necessary for monitoring of plant operation and process control continuously. The purposes of flow devices are: a) b) c) d)
5.11.2
to maintain flow records periodically for future reference, especially when plant expansion is needed.
to identify the flow pattern which may be due to population growth or infiltration. Statutory requirement by the DOE to maintain flow records at all sewage works. To establish operational cost for treatment of sewage.
Design Requirements for Flow Devices Flow devices are mandatory for all STP, regardless of size.
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Table 5.23 Design Parameters for Flow Devices Design Criteria
Description
Location of flow meter Type of Flow Measurement Type of flow meter
Method of measurement
Measurement times
PE ≤ 5,000
PE > 5,000
Inlet or Outlet
Inlet and Outlet
Closed Conduit or Open Channel V- notch (Outlet Only) Rectangular Weir (Outlet Only) Flumes
Closed Conduit or Open Channel V-notch (Outlet Only) Rectangular (Outlet Only) Flumes
Electromagnetic
Electromagnetic
Ultrasonic • Automated or manual measurement of Staff gauge to measure height of crest with calibration curves / tables Continuous or Intermittent
Ultrasonic Automated devices linked to data logging with integrator and transmitted to chart recorder (minimum 7 days chart time) Continuous
5.12
Sludge Holding, Treatment and Disposal
5.12.1
Introduction All treatment processes are capable of producing significant quantities of sludge which requires to be further treated. The sludge comprises essentially inert and organic matters that are biodegradable and nonbiodegradable present in sewage, and bacterial cells generated by the biological treatment processes. The treated sludge, often referred as biosolids is ready for safe disposal or reuse. The importance of sludge management increases with the increase in the amount of sewage treated. Space has to be allowed within the premises of an STP to accommodate sludge treatment, handling and storage facilities. All sludge need to be treated for safe disposal back to the environment. The minimum requirement for sludge treatment is to achieve stabilize sludge with a 20% dry solid content.
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For large scale development whereby the full sludge generation will only be achieved over a certain time period, proper sizing/modulation of sludge treatment facilities need to be provided in order to achieve the immediate needs for sludge treatment. 5.12.2
Sludge Strategy in General Figure 5.20 shows the typical sludge treatment and disposal strategy which consists of three main stages. a)
Stage 1 - Preliminary treatment and digestion
c)
Stage 3 - Utilisation and disposal
b)
I)
Stage 2 - Conditioning and dewatering
Stage 1 - Preliminary Treatmentand Digestion
Preliminary treatment may include reception or holding facility for screened sludge, primary thickening and digestion facilities. For imported sludge the reception facility may comprise of an unloading area, screen chamber, reception tank and transfer pump(s). Thickening equipment, such as, centrifuge, drum thickener or gravity belt thickener is provided to thicken the raw screened sludge from about 1% dry solids content to about 6% dry solids content. To assist the thickening process, an ‘in-line’ polymer dosing system or chemical conditioning shall be provided. Two types of digestion facilities are available for digestion after the thickening: aerobic and anaerobic digestion. Secondary thickening is recommended to reduce the volume of digested sludge, which will then reduce the size and the number of the next treatment process unit, i.e., dewatering equipment. II)
Stage 2 - Conditioning and Dewatering
Dewatering can be achieved by two (2) methods : mechanical dewatering and non-mechanical dewatering. a)
Mechanical dewatering such as belt filter press, centrifuge or filter press is provided for sludge dewatering purposes. To assist the mechanical dewatering equipment in achieving optimum level of cake dryness, an ‘in-line’ polymer dosing system or chemical conditioning shall be provided.
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b)
Non-mechanical dewatering, e.g. drying beds or sludge lagoons is often used For a facility serving ≥ 10,000 PE, the drying beds must be designed to support mechanical/machine lift for the purpose of clearing the dried sludge. Sludge lagoons of about 2 m depth are also used for sludge stabilisation and drying. The sludge lagoons shall be sized to receive sludge for a period of at least 6 months and are allowed to undergo stabilisation through evaporation and drying for another 6 months period. The lagoons shall be lined with either PVC lining, concrete or 600 mm thick clay lining. An access ramp shall be provided to allow mechanical equipment access to clean dried sludge.
III)
Stage 3 - Utilisation and Disposal
After the dewatering process, an on-site storage for 30 days of the treated bio-solid shall be provided. The storage structure shall be covered with roof and provided with partly opened walls to allow for proper ventilation. Finally, the bio-solid is either composted and/or applied directly for land reclamation (i.e., for ex-mining land), land application (i.e., for certain types of agriculture land and forest land/reforestation) or used as top soil cover at land fill site. The ultimate disposal of bio-solid is the responsibility of the plant operator. 5.12.3
Provision of Sludge Holding, Treatment and Disposal The Service Licensee will advise on current capacity in its existing sludge treatment facilities, suitable sludge stabilisation, dewatering and final disposal of the sludge shall be provided. If the Service Licensee has the capacity to receive sludge generated from the development, then the project proponent has the option to negotiate with the Service Licensee to dispose off the sludge at the existing facility. In this case, a sludge storage tank with a minimum capacity to hold for 30 days with the sludge thickened to 1% solids is acceptable. Otherwise, the sludge shall be stabilised, dewatered and prepared in a suitable form for disposal. Different types of STPs produce different quantities of bio-solid. The principal assumptions adopted on waste generation rates are summarised in Table 5.24.
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Table 5.24 - Sludge Generation Rates Treatment System
Unit Generation Rates
Comments
Primary Sludge Primary Clarifier
0.5 kg sludge/kg solids input
Based on continuous sludge withdrawal
Imhoff Tank
0.15 kg sludge/kg SS input
Based on average 6 month desludging period
Conventional Activated Sludge System
0.8 to 1.0 kg sludge/kg BOD5 removed
Standard A/B
Extended Aeration or Oxidation Ditch
0.4 to 0.6 kg sludge/kg BOD5 removed
Standard A/B
RBC/SBC/High Rate Trickling Filter System
0.8 kg sludge/kg BOD5 removed Standard A/B
Hybrid System
0.4 kg sludge/kg BOD5 removed Standard A/B
Secondary Sludge
Note: Based on the above assumptions, the quantity of waste sludge requiring treatment and disposal can be estimated. Refer also to design guides related to each of the above individual processes.
5.12.4
Design Criteria The ultimate aim of sludge treatment is to achieve at a minimum stabilised sludge with dry solids content of 20% for final disposal. A combination of various unit processes may be used to achieve this minimum requirement. I) a) b) c)
Sludge Reception/Sludge Holding An unloading area is normally provided to receive sludge tankers delivering imported sludge to the facility, if necessary. It should also includes a parking area for sludge tankers. A mechanically raked screen with 12 mm opening together with a manually raked by-pass screen shall be provided where necessary. Connection fitted female coupling with ball valve shall be provided at the reception facility for the connection of desludging tanker’s hose.
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d)
Minimum three (3) days sludge holding capacity of between 1 to 4% dry solids content sludge (depending on the types of sludge) shall be provided after the screening process.
e)
Overflow pipe shall be provided at sludge holding tank to aeration tank to avoid overflowing.
f)
II)
Adequate ventilation/air extraction fan shall be provided at the thickening/dewatering house. Solid Thickening
Thickening is a process used to increase the solids content of sludge by removing a portion of the liquid fraction. It is generally accomplished by physical means, including co-settling, gravity settling, flotation, centrifugation, gravity belt and rotary drum. The design parameters for sludge thickening equipment shall follow Table 5.25 below: Table 5.25 - Design Parameters for Sludge Thickening
Type of Thickening
Picket Fence Gravity Thickener
% Dry Solids
1.5
Dissolved Air Flotation
2
Belt Thickener
4
Drum Thickener
4
Centrifuge
4
Polymer System
Speed of Sludge feed pump
Backwash water system
n/a
n/a
n/a
< 300 rpm
Yes
Yes with appropriate polymer turndown ratio
Note: a) Mechanical thickener shall be designed for 8 hrs/day and 5 days/week operation. b) For belt, drum and centrifuge thickener, three polymer injection points shall be provided c) Potable water to be provided for polymer mixing system.
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III)
Solid Digestion
Sewage biosolids in its natural state (raw) is rich in pathogenic organisms, easily putrescible and rapidly developing unpleasant smells. Stabilization processes were developed with the purpose of stabilizing the biodegradable fraction of organic matter present in the bio-solids, thus reducing the risk of putrefaction as well as diminishing the concentration of pathogens. The stabilization processes can be divided into: a)
b) c)
Biological stabilization – specific bacteria promote the stabilization of the biodegradable fraction of the organic matter.
Chemical stabilization – chemical oxidation of the organic matter accomplishes sludge stabilization. Thermal stabilization – heat stabilizes the volatile fraction of sludge in hermetically sealed containers.
The most widely used stabilization process is biological stabilization via anaerobic and aerobic digestion. Table 5.26 - Design Parameters for Aerobic and Anaerobic Digestion
Description
Number of Tank, Minimum
Min. Solids Retention Time Organic Loading Rate
Typical Feed Solids Concentration
Unit
No.
Days
KgVS/m3.d %
Type of Mixing
m
Tank Dimension, maximum
m
Dissolved Oxygen
Sewage Treatment Plants
Aerobic Digestion
Anaerobic Digestion
10
18
2
1.6 – 4.8 2
Aerators Diffusers
Min. Water Depth, minimum
Tank Shape
Design Criteria
mg/L
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Cylindrical Rectangular 25 diameter 25 length 1-2
2
0.8 – 1.6 2-6
Gas Injection Mechanical Stirring Mechanical Pumping 7.5
Cylindrical Egg-Shaped 25 diameter -
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IV)
Sludge Dewatering
Table 5.27 Recommended Design Parameters for Sludge Stabilisation and Dewatering Descriptions
Sludge Stabilisation Type of stabilisation process
Hydraulic retention time (HRT) minimum
Design Considerations
Unit
PE ≤ 2,000
PE > 2,000
Simple anaerobic or aerobic digestion
Ambient anaerobic digestion with good mixing facility
Days
Dewatering
Type of device
30
30
Belt press Centrifuge Filter press Drying bed
Belt press Centrifuge Filter press Drying bed *
Operating period of mechanical thickening and dewatering facility
5 days/week # 8 hours/day 250 days/year
5 days/week # 8 hours/day 250 days/year
Covered storage area
1 month holding
Minimum dry solids (content after dewatering)
Handling capacity of drying bed
%
20
4 weeks cycle on 450 mm thick feed †
20
4 weeks cycle on 450 mm thick feed †
1 month holding
Notes: a) Access ramp of at least 1.5 m wide shall be provided at all sludge drying beds * # †
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Drying beds must be designed to support mechanical/machine lift for more than 10 000 PE. Design to be based on one full-time working shift only. In computing the area requirements of a sludge drying bed, the designer may assume a maximum 450 mm depth of sludge feed to the bed. The actual quantity of sludge from the upstream unit processes needs to be computed before sizing the bed. Each bed may be designed to handle a maximum of 7 days continuous feed. The next feed to the same bed shall only be after a minimum of 21 days from the last feed. A one-third (1/3) reduction in actual land area requirement will be acceptable if fully covered drying beds are provided. Reduction shall only apply to the total surface area of drying Volume 4
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Requirements for Individual Treatment Processes for thickness. Stages of Sewage Treatment and bed. No reduction is allowed for theRequirements drying bed Structures materials used for the drying bed covers shall be designed to an acceptable structural strength andused of acceptable to withstand local weather Structures and materials for the dryingquality bed covers shall be designed to an conditions. acceptable structural strength and of acceptable quality to withstand local weather
conditions.
Figure 5.20 Sludge Treatment and Disposal Strategy Figure 5.20 – Sludge Treatment and Disposal Strategy Untreated Sludge
Screening
Primary Thickening Preliminary Treatment and Digestion
Anaerobic Digestion
Aerobic Digestion (Optional)
Secondary Thickening (Optional)
Possible disposal of Liquid Sludge
Chemical Conditioning Conditioning and Dewatering Mechanical Dewatering
Drying Beds
Drying Lagoons
Storage at works Utilisation and Disposal
To inlet of STW or on-site Liquor Treatment Plant
Composting Transportation from works
Land Reclamation
Sewage Treatment Plants Sewage Treatment Plants
Land Application Forestry/Agriculture
Landfill Site
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V)
Ultimate Disposal The treatment plant project proponent has to indicate in the proposal the ultimate disposal options and actual volume for disposal throughout the life time of the plant.
5.13
Tertiary Treatment
5.13.1
Introduction Tertiary treatment is associated with the requirements to further reduce or remove pollutants beyond the levels achieved by common secondary treatment processes. Such requirements can be in the forms of the removal of nutrients, such as, nitrogen and phosphorus; lower BOD5 or SS levels; or trace elements of toxic constituents, such as, heavy metals or refractory organics. The various methods of tertiary treatment include simple maturation ponds, adsorption, chemical treatment and filtration; air stripping, mambrane or reoxygenation. Tertiary treatment is required before discharging to very sensitive receiving waters. The Commission will specify the need for such treatment on a case-by-case basis, depending upon the sensitivity of the project.
5.13.2
Design Requirement I)
Filtration system
a)
Filtration is the most common tertiary treatment system used to remove suspended or colloidal matter in the effluent.
b)
c) d) e) f)
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Backwashing shall be limited to once per day. The volume of backwash water shall not exceed 10% of plant throughout. Backwash water shall be stored in a buffer tank before being return to the inlet of the plant. Where used, the facility for dosing conditioners shall be provided at the inlet of the filter system. On-line turbidity meter, level detector and flow measurement shall be utilized to measure filter performance.
If the filters are housed in a building, adequate and safe access shall be provided for maintenance purposes.
The filters shall have automated backwash features and sized adequately to allow continuous filtration.
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g)
For package plants, it is preferred to use FRP as the filter vessel. However, fabricated steel is also acceptable provided that protective coatings are included. For larger plants, the use of reinforced concrete is encouraged.
II)
Adsorption (Activated Carbon)
b)
Adsorption shall be preceded by filtration using granular media to ensure a consistant feed quality, which is affected by pH, temperature and flow rate.
a)
c) d) e)
Activated carbon is used to remove small quantities of refractory organics, as well as inorganic compounds, such as nitrogen, sulficles and heavy metals.
Uniform feedwater to avoid any surges that might adversely affect the carbon adsorption. Clarity of feedwater is important to avoid restriction of pores or build up of materials within the pore structure.
Backwashing rate and the frequency required depend on the hydraulic loading and operational method. Typical duration of backwashing is 10-15 minutes.
III)
Chemical Treatment
b)
Phosphorous precipitation requires the addition of coagulants, which usually are lime, alum, sodium aluminate, ferric chloride and ferrous sulfate.
a)
c)
Chemicals can be used as tertiary treatment for acid-base neutralisation and precipitation of phosphorous.
Dosing systems and safety features to be provided to assure the operation and maintenance of the systems can be carried out in a safe and healthy environment.
IV)
Air Stripping
b)
The design features shall depend on the required level of nitrogen removal with the critical parameters being tower packing, quantity of air supply, air and liquid temperatures and process control measures.
a)
This method is used to remove ammonia nitrogen (NH4 – N) from effluent.
V)
Reoxygenation
a)
This method is used to increase the dissolved oxygen (DO) levels in the effluent.
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Requirements for Individual Treatment Processes
b)
The different types of reoxygenation systems are cascade, reoxygenation and mechanical reoxygenation
Requirements for Individual Treatment Processes c) Cascade reoxygenation
is achieved using on the hydraulic design of structures, such as, weir overflows, flumes, spillways, etc.
d)
b)
e)
d)Design Mechanical reoxygenation is achieved using mechanicalisequipment of structures or mechanical equipment based such as surface aerators, jet diffusers or diffused air (coarse, fine amount of DO required for the effluent. bubble, etc.)
VI) a)
The different types of reoxygenation systems are cascade,
Mechanical reoxygenation is achieved using mechanical equipment reoxygenation and mechanical reoxygenation as surface aerators,is jet diffusers or the diffused (coarse, fine c)such Cascade reoxygenation achieved using on hydraulicair design of bubble, etc.) such as, weir overflows, flumes, spillways, etc. structures,
e)
on the
Design of structures or mechanical equipment is based on the
amount of DO required for the effluent. Maturation ponds
PondMaturation systems are normally not encouraged because it requires ponds large land area and the inherent difficulty in controlling algal a) Pond systems are normally not encouraged because it requires large growth. In special cases, difficulty where land is in abundance, land area and the inherent in controlling algal growth.the In project proponent may where choose use this system. special cases, landtois in abundance, the project proponent may
(VI)
choose to use this system.
Figure 5.21 Typical Roof Details for Covered Sludge Drying Bed Figure 5.21 – Typical Roof Details for Covered Sludge Drying Bed
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Requirements for Ancillary Facilities
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6.1
Introduction This section defines the minimum requirements of ancillary facilities to be provided at the sewage treatment plants. These requirements are crucial in ensuring the workability and operability of the plants.
6.2
Water Supply and Wash Water Water shall be supplied to each site from standpipes and taps, to provide for sanitary cleansing of plant areas, personal hygiene, safety, fire fighting, process use and for equipment cooling and/or sealing. Water shall be connected to potable supply that provides a minimum pressure of 20 m head across the site. A ring main system shall be provided for all treatment plants larger than 5000 PE. Each sewage treatment plant or sludge treatment facility shall be provided with water tank of at least 445 litre storage capacities or one day water usage or whichever is higher. Double backflow prevention shall be provided in all cases. This is to prevent contamination of any potable water service, including the incoming supply line. The water supply system shall be sized to meet the following cases:
i) ii)
Fire fighting demand as instructed by the local regulations and any essential plant water demands.
All potentially simultaneous process uses, equipment uses and a for plant cleansing.
All water supplies and its installation (piping, tanks, air conditioning drainpipes, gutters and etc.) must be totally isolated from all potential contact of electrical system by means of total enclosure or suitably located the electrical system above flood level. Where required, wash water shall be equipped with booster pump and where possible, obtain from reclaimed water. Drawings submitted for approval shall indicate locations of water tapping point and piping layout. Approval for water tapping should be obtained from water authority for permanent water supply before submitting inspection form. All related document, such as water bills and transfer of ownership, to be submitted before final inspection. Table 6.1 tabulates the minimum number and location of stand pipe required in a sewage treatment plant. Typical drawing of stand pipe are shown in Figure 6.1 Sewerage Treatment Plants
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Requirements for Ancillary Facilities Requirements for Ancillary Facilities
Table 6.1 – Minimum Number of Recommended Water Table 6.1 Minimum Number of Recommended Water Stand Pipe and Location Stand Pipe and Location Class of Class of STP STP
1 1 22
33 4 4
Population Population Equivalent Equivalent
1,000 ≤1000 1,001 – 1001 – 5000 5,000 5001 – 20– 000 5,001 20,000 >20 000 >20,000
Minimum Minimum Numbers Numbers
Location Location
1 1 2 2
Inlet Works Inlet Works Inlet Works and Treatment Inlet Works and TreatmentProcess ProcessUnit Unit
2 2
Inlet Works and TreatmentProcess ProcessUnit Unit Inlet Works and Treatment
4
4
Inlet Works, Secondary Screen Area, Inlet Works, Secondary Screen Area, Treatment Process Units and Dewatering Treatment Process Units and Dewatering Facilities. Facilities.
Figure 6.1 Standard Details for Stand Pipe Figure 6.1 Standard Details for Stand Pipe
800 76
648
76
64 8
76
608
Ø15 G.I PIPE
76
80 0
100
STAND PIPE
6.3 6.3
Mess Facilitiesand andAblutions Ablutions Mess Facilities
All plants shall shallhave havea aminimum minimum sanitary set consisting All treatment treatment plants of of oneone sanitary set consisting of of a toilet and wash basin. Washing facilities, toilets and showers shall a toilet and wash basin. Washing facilities, toilets and showers shall be be provided operators all Class and 4Class plants PE provided for for operators at allatClass 3 and 3Class plants4with PE with greater
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Requirements for Ancillary Facilities Requirements for Ancillary Facilities
greater than 5000. Additionally, mess accommodation shall be provided than mess accommodation at 5,000. Class 4Additionally, treatment plants with PE greatershall thanbe20provided 000. at Class 4 treatment plants with PE greater than 20,000.
Guard house with water and power supply shall also be provided for Guard house with water and power supply shall also be provided for plant plant more than 20 000 PE. more than 20,000 PE. Figure 6.2 Typical for Administration and Mess Facilities Building Figure 6.2 Typical for Administration and Mess Facilities Building
16
Visitor’s / Staff Parking
Covered Porch
Manager’s / Engineer’s Office
2
3
1
4
Reception Area
General Office
Supervisor's Office
5 Meeting / Briefing Room
14 8
Workshop
Sample Reception & Preparation
7
Male Toilet
7
Female Toilet
9
Prayer Room
6
12
Control Room
9
Clean Locker Room Recreation Area
10 Pantry
13
11
General Store
Eating Area
16
Note :
Sewerage Treatment Plants
Sewage Treatment Plants
Dirty Locker Room
9 Toilet / Shower
Motorcycles / Operational Vehicles Parking
The numbers on the layout correspond to the numbers in Table B.1. The layout is only for indicative purposes only and can be changed ( i.e. floor space and other arrangement) to suit the plant’s needs and requirements.
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Requirements for Ancillary Facilities Requirements for Ancillary Facilities Requirements for Ancillary Facilities
6.4 6.4 6.4
Minimum internal floor area of mess facilities are 400 meter 2 . Minimum from internal area of mess facilities are 400 meter2. floor Approval Approval thefloor Commission shall be sought if smaller area 2 from theinternal Commission shallofarrangement be sought ifof smaller floor is to bein Minimum floor area mess facilities are 400 meterarea . is Approval is to be provided. Typical mess facilities shown provided. Typical arrangement mess facilities is shown Figure 6.2be from the 6.2 Commission shall be ofsought if smaller floor in area is to Figure provided. Typical arrangement of mess facilities is shown in Figure 6.2
Roads and Roads andAccess Access Roads and Access
All-weather, surfaced surfaced roads All-weather, roads shall shall be be provided provided to to permit permit access access toto all all treatment plants. The roads must withstand a load of at least 15 tonnes. All-weather, surfaced roads shall be provided to permit access to all treatment plants. The roads must withstand a load of at least 15 tonnes. Such roads roads must also be within plant access to treatment plants. must withstand a the load of atproviding least 15 tonnes. Such mustThe alsoroads beconstructed constructed within the plant providing access each process The construction shall with Such roads must unit. also be constructed within thecomply plant providing accessWork to to each process unit. The construction shall comply withPublic Public Work Department requirement. Figure 6.3 and Figure 6.4 illustrate the typical The construction shall comply with Public Work each process unit. Department requirement. Figure 6.3 and Figure 6.4 illustrate the typical section of road pavementFigure and site road. Department Figure 6.4 illustrate the typical section of requirement. road pavement and 6.3 siteand road. section of road pavement and site road. Figure 6.3 Typical Details of Road Pavement Figure 6.3 Typical Details of Road Pavement Figure 6.3 Typical Details of Road Pavement 40 THK. WEARING COURSE
60 THK. PREMIXCOURSE BINDER COURSE 40 THK. WEARING 10 THK. SAND/QUARRY DUST 60 THK. PREMIX BINDER COURSE 10 THK. SAND/QUARRY DUST
300 THK. CRUSHER RUN 50 THK SAND 300 THK. CRUSHER RUN 50 THK SAND
Figure 6.4 Typical Road Section of Site Road Figure 6.4 6.4 Typical TypicalRoad RoadSection Section of Site Figure SiteRoad Road 4000 4000 ROAD KERB ROAD KERB
ROAD KERB FALL
FALL
FALL
ROAD KERB
FALL
40 THK. WEARING COURSE 60 THK. PREMIX BINDER COURSE 40 THK. WEARING COURSE 250 THK. ROADBASE 60 THK. PREMIX BINDER COURSE THK. SUB-BASE 250150 THK. ROADBASE GEOTEXTILE MEMBRANE APPROVED BY ENGINEERS 150 THK. SUB-BASE GEOTEXTILE MEMBRANE APPROVED BY ENGINEERS
152
140 140
The on-site road shall be able to provide safe and convenient access for trucks or other equipment usedsafe for and maintenance purposes. The The on-site road machinery shall be able to provide convenient access for trucks or other machinery equipment used for maintenance purposes. The Volume 4 Malaysian Sewerage Industry Guidelines
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Malaysian Sewerage IndustrySewerage Guidelines Malaysian
Requirements for Ancillary Facilities
The on-site road shall be able to provide safe and convenient access for trucks or other machinery equipment used for maintenance purposes. The minimum width of the road shall be 4 meter Where vehicles need to pass frequently or parking is required along the road, the minimum width shall be 6 m. Corner of junction for perimeter internal road for tankers or trucks access shall have a minimum inside radius of 6 meter. Inside radius for perimeter road not intended for tankers or trucks access shall be not less than 4 m. Cul-de-sac at the end of roads shall be provided with turning area reserve of not less than 9 m. Where roads for maintenance vehicles or machineries are not required, concrete or hard surfaced walkways of at least 900 mm width shall be provided between each process unit. Concrete hardstanding area can be laid where storage bins are located. The use of steps shall be avoided, where possible. Where the ingress or egress of the treatment plant is near a junction of a public road, an adequate acceleration and deceleration lane must be made available between the access road and the junction for vehicles to safely enter and leave the treatment plant. Vehicular access shall be provided to all unit processes that require daily operation and maintenance.
6.5
Drainage The area of the treatment plant shall be adequately drained and this shall be arranged to prevent surface water run-off from entering the process units. Any cleaning or maintenance process wash water must be returned to the inlet works via a separate drainage system. External drainage facilities must be provided for treatment plant along the slope area. Cut off drainage at the entrance must also be provided.
Treatment plant platform level shall be designed above flood level. If the treatment plant is located in a flood prone area, flap gate shall be provided to avoid back flow from the river/ main drain. The plant hydraulic must be designed properly to ensure the discharge head is adequate to open the flap valve at any circumstances.
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The effluent discharge shall be directed to the main drain or river to avoid discharging effluent into a drain within the residential area. Discharge to a retention pond is not allowed unless prior approval has been granted. The receiving drain/watercourse shall have sufficient capacity to accept the run-off from the plant as well as the effluent discharge from the treatment plant.
6.6
Fencing and Security The boundary of a treatment plant, pumping station and/or sludge treatment facility shall be secured by 3.0 meter high fence. The perimeter fence shall have an entrance by double gates or sliding barrier to allow access of maintenance vehicles. The gates shall be secured by padlocks and shall comply with the requirements of the Commission. Where the treatment plant is situated in a building, access to the plant must be secured. The fence shall be 2.4 meter solid wall with three strands of 0.6 meter high barbed wire. Typical details of the fence are given in Figure 6.5, 6.6, 6.7 and 6.8. STP project proponent is required to provide adequate warning/safety and the Commission signboard before handing over the sewerage system to the Commission.
154
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X
X
X
600
X
X
Sewerage Treatment Plants
Volume 4
Sewage Treatment Plants
Volume 4
X
INTERNAL
COLUMN @ 3m
CONCRETE
6"x6"
X
3 NOS. 2.5 DIA. BARBED WIRE
X
X
X
X X
BRICKWALL FENCE
X
3000
X
X X
X
63 x 63 x 6 THK. ANGLE
X
225
X X
X
150
225
X
M.S. POST
150 DIA. X 14.6 #
600 x 600 x 900 DEEP GRADE 20 MASS CONCRETE STUMP
X
3 THK. M.S. PLATE
4200
X X
600 SQ.
X
X X
2100
X
X X
X X
X X
BRICKWALL FENCE
X
X
X
X X
3 NOS. 2.5mm DIA. BARBED WIRE
Requirements for Ancillary Facilities Requirements for Ancillary Facilities
Figure 6.5 Typical Drawing of Brickwall Fencing and Gate Figure 6.5 Typical Drawing of Brickwall Fencing and Gate
900 150
2400
155
14 3
300
2200
MIN. 900
2T12
750
300
300
750
75
2T12
2T12
750
63 x 63 x 6mm M.S. ANGLE WITH 3 STRANDS OF BARBED WIRE
750 x 750 x 230mm FOOTING
150 x 300mm GROUND BEAM
115mm THICK CEMENT / SAND BRICKWALL WITH 20 PLASTERING BOTH SIDES
100 x 125mm COPING BEAM
45°
2T12
B
B
A
A
T12
R6-200
750 x 750 x 230mm RC FOOTING
T12
T12
150
R6-200
T12
T12 T12
T12
R6-100
300
750
C
4T12 B/W
FINISHED GRD. LEVEL
SURFACE TO BE ROUGHENED
LINKS R6-150
4T12
TYPICAL RC COLUMN DETAIL
C
230
3.) NTERIOR/EXTERIOR WALL COLOUR STANDARDS - DULUX TUNGSTEN (10412) OR EQUIVALENT
2.) TWO BANDS OF IWK'S COLOUR WITH OVERALL HEIGHTS OF 400mm SHALL BE PAINTED ON EXTERIOR FACE OF THE WALL.
APPROVED WEATHER RESISTANT EMULSION PAINT.
1.) ALL EXPOSED WALL SHALL BE PAINTED WITH ONE UNDERCOAT OF APPROVED RESISTING PRIMER SEALER AND TWO COATS OF
PAINTING
7. PLASTERING AND RENDERING TO SURFACE OF BRICKWALL SHALL BE FINISHED TO A MINIMUM THICKNERS OF 20mm WITH 1:3 CEMENT-SAND NORTAR.
6. MORTAR FOR BRICKWORK SHALL BE SET IN 1:1:5 CEMENT-LIME-SAND MORTAR.
5. BRICKWORK WALLS SHALL BE ANCHORED TO CONCRETE FACES USING GALVANISED FISHTAIL A NCHORS TO LAP IN WITH THE BRICK REINFORCEMENT AT EVERY FOURTH COURSE COMMENCING TWO COURSES ABOVE GROUND BEAM LEVEL.
4. BRICKWORK SHALL BE REINFORCED WITH EXPANDED METAL OR "EXMET" AT EVERY FOURTH COURSE COMMENCINGS TWO COURSES ABOVE GROUND BEAM LEVEL.
3. ALL BRICKS USED SHALL BE FIRST QUALITY CEMENT / SAND BRICKS.
2. MINIMUM COVER TO REINFORCEMENT SHALL BE 25mm.
230
SECTION C-C
T12
T12
FINISHED GRD. LEVEL
115mm THK BRICKWALL PLASTERED ON BOTH SIDE
230 x 230mm RC COLUMN AT 3.2m INTERVALS
50mm LEAN CONCRETE
2T12
2T12
SECTION B-B
750
300
1. ALL CONCRETE USED SHALL BE GRADE C25.
NOTES :
SECTION A-A
T12
125
2T12 115 x 300mm GROUND BEAM
R6-150
2T12
R6-200 100 x 125mm COPING BEAM
FRONT VIEW OF BRICKWALL FENCING
50mm LEAN CONCRETE
115 x 300mm GROUND BEAM
R6-150
R6-200 100 x 125mm COPING BEAM
TYPICAL CROSS SECTION OF BRICKWALL FENCING
3 STRANDS P.V.C. COATED BARBED WIRE ATTACHED TO POST BY HEAVY SPLIT PINS
230
2T12
100
2T12
800
2200
MIN. 900
Volume 4
230
230
800 2200 MIN. 900
156 230
3200
Requirements for Ancillary Facilities
Figure 6.6 Brickwall Fencing
Malaysian Sewerage Industry Guidelines
800
Sewerage Treatment Plants
2200
Volume 4 800 PRE-CAST CONCRETE WALL 75mm THICK
T12
T12
FINISHED GRD. LEVEL
SURFACE TO BE ROUGHENED
LINKS R6-150
4T12
230
TYPICAL RC COLUMN DETAIL
45°
300
2200
- GREEN
- DULUX GLOSS FINISH (PANTONE 354C) OR EQUIVALENT
3.) COLOUR STANDARDS A.) INTERIOR/EXTERIOR WALL - DULUX TUNGSTEN (10412) OR EQUIVALENT B.) BANDS - BLUE - DULUX GLOSS FINISH (PANTONE 300C) OR EQUIVALENT
PAINTING 1.) ALL EXPOSED WALL SHALL BE PAINTED WITH ONE UNDERCOAT OF APPROVED RESISTING PRIMER SEALER AND TWO COATS OF APPROVED WEATHER RESISTANT EMULSION PAINT. 2.) TWO BANDS OF IWK'S COLOUR WITH OVERALL HEIGHTS OF 400mm SHALL BE PAINTED ON EXTERIOR FACE OF THE WALL.
3. FOUNDATION AS PER THE DESIGN OF THE ENGINEER-IN-CHARGE.
1. ALL CONCRETE USED SHALL BE GRADE C25. 2. MINIMUM COVER TO REINFORCEMENT SHALL BE 25mm.
NOTES :
230
SECTION A-A
T12
230
PRE-CAST CONCRETE WALL 75mm THICK
63 x 63 x 6mm M.S. ANGLE WITH 3 STRANDS OF BARBED WIRE
T12
R6-100 C/C
FINISHED GRD. LEVEL
PRE-CAST CONCRETE WALL 75mm THICK
230 x 230mm RC COLUMN AT 3m INTERVALS 2200
TYPICAL CROSS SECTION OF PRE-CAST FENCING
75
FRONT VIEW OF PRE-CAST FENCING
3200
800
3 STRANDS P.V.C. COATED BARBED WIRE ATTACHED TO POST BY HEAVY SPLIT PINS
3200
Requirements for Ancillary Facilities
Figure 6.7 Precast Fencing
157
158
146
B
B
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Volume 4
390mmx190mmx190mm BOND BEAM BLOCK
1 NO HORIZONTAL REINFORCEMENT
390mmx190mmx114mm FULL BLOCK
390mmx190mm190mm BOND BEAM BLOCK
1 NO. HORIZONTOL REINFORCEMENT
ANTI-CLIMB
ELEVATION
2. ALL MASONRY UNITS (CONCRETE BLOCKS) USED MUST BE UNDER SIRIM CERTIFICATION SCHEME
- GREEN
B.) BANDS - BLUE
- DULUX TUNGSTEN (10412)
(PANTONE 354C) OR EQUIVALENT
- DULUX GLOSS FINISH
(PANTONE 300C) OR EQUIVALENT
- DULUX GLOSS FINISH OR EQUIVALENT
A.) INTERIOR/EXTERIOR WALL
3.) COLOUR STANDARDS
2.) TWO BANDS OF IWK'S COLOUR WITH OVERALL HEIGHTS OF 400mm SHALL BE PAINTED ON EXTERIOR FACE OF THE WALL.
1.) ALL EXPOSED WALL SHALL BE PAINTED WITH ONE UNDERCOAT OF APPROVED RESISTING PRIMER SEALER AND TWO COATS OF APPROVED WEATHER RESISTANT EMULSION PAINT.
PAINTING
4. CEMENT MORTAR USED FOR JOINTS TO BE 1:3 MIX
3. CONCRETE MIX USED FOR GROUTING TO BE GRADE 20
390mm x 190mm x 190mm BOND BEAM BLOCK
1 NO HORIZONTAL REINFORCEMENT
390mmx190mmx190mm FULL BLOCK
390mmx190mmx190mm BOND BEAM BLOCK
63 x 63 x 6mm M.S. ANGLE WITH 3 STRANDS OF BARBED WIRE
SECTION A-A
1. FOUNDATION AS PER THE DESIGN OF THE ENGINEER-IN-CHARGE
NOTE :-
SECTION B-B
3 STRANDS P.V.C. COATED BARBED- WIRE ATTACHED TO POST BY HEAVY SPLIT PINS
Requirements for Requirements for Ancillary AncillaryFacilities Facilities
Figure 6.86.8 Masonry Masony Fencing Figure Fencing
Malaysian Sewerage Industry Guidelines Malaysian Sewerage Industry Guidelines
Requirements for Ancillary Facilities
6.7
Beautification Zone and Landscape Treatment plants shall be effectively and visually screened by a beautification zone within the treatment plant site of not less than 2 m wide, on which selected species of trees and shrubs can be planted. In congested or difficult locations, the Commission should be consulted on these requirements. Premix or Paved area shall be provided at this zone for all class 1 treatment plants with loading equal or less than 1000 PE or where necessary.
6.8
Stores and Workshops All Class 4 Treatment plants that exceed 20 000 PE and have a pump station within the premises shall be provided with an active store and workshop.
6.9
Spares All mechanical units shall be provided with an adequate reserve supply of critical spare parts. A list of proposed spare parts should be forwarded for approval when detailed designs are submitted for verification and approval. All parts recommended by the manufacturer to be provided with spares shall be so delivered at the stage of final inspection. Notwithstanding that, all parts with a life span of 3 years or less shall be provided with spares Typical spare parts requirements are provided in Table 6.2. Spare parts shall be obtained from the original manufacturer of the equipment and shall be packed and protected for storage to BS1133 requirement. A set of special tools if required and specific to an equipment including lifting tackle and greasing equipment necessary for the maintenance, repair, testing and overhauled of the equipment shall be supplied together with the spares at the stage of final inspection.
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Requirements for Ancillary Facilities
Table 6.2 Spare Part No.
1.
2.
3
Pumps: Raw Sewage Submersible Pumps. Grit Pumps. Feeding Pumps. RAS Pumps. Sludge Pumps. Effluent Pumps.
Motors (Electric):
Drives a)Direct Couple b)Chain
4
c)Belt Mechanically Raked Screens
5.
Diaphragm Pump
6. 7. 8.
9.
10.
160
Equipment
Progressive Cavity (Mono) Pump Blowers
Spare Parts
Bearing o-ring oil seal mechanical seal wear ring Impeller (for 3 or more pump of similar model) (see Pumps, Motors, Drives)
one set one set one set one set one set one set one set, whichever parts is relevant
Bearing o-ring oil seal mechanical seal
one set one set one set one set
gear bearing chain sprocket V-belt Chain Chain link Gear sprocket (also see Motors, Drives) diaphragm
one set one set one set one set one set one set one set one set, whichever parts is relevant one set
(see Motors, Drives)
one set, whichever parts is relevant
rubber stator
Aerator: Diffused Air Diffusers Mechanical (surface, (see Motors, Drives) brush) Scraper rotating collectors wheel (see Motors, Drives) Conveyor
Quantity
(see Motors, Drives)
Volume 4
one set
10% of total numbers one set, whichever parts is relevant one set one set per clarifier one set, whichever parts is relevant one set, whichever parts is relevant
Malaysian Sewerage Industry Guidelines
Requirements for Ancillary Facilities
Table 6.2 Spare Part (continued)
6.10
Yard Lighting
No.
Equipment
Spare Parts
Quantity
11.
Filter Press
oil seal for hydraulic pump membrane cloth
one set one pair out of every five pair of plates
12.
Belt Press
oil seal for hydraulic pump Belt
one set one set if the STP has only one press
13.
Centrifuges
(see Drives)
one set, whichever parts is relevant
6.10
Yard Lighting
Effective yard and building lighting systems shall be incorporated within the treatment plant site in order to provide sufficient illumination for operation and maintenance schedules to be carried out during day and night periods. In addition, the entire treatment plant site shall have sufficient street lights and perimeter lights for various operations, safety and security reasons.
Compound lighting shall be provided at every 50 m interval for all manned and security plants. However, sufficient lighting is required at the strategic location such as entrance gate, inlet works and necessary areas. Refer to Table 6.3.
All lighting shall be accessible for maintenance / removal. Typical details of compound lighting are shown in Figure 6.9.
Table 6.3 Numbers of Unit and Location of Compound Lighting Class of STP
Population Equivalent
Minimum Numbers of Unit
1
≤1 000
1
2
1001 – 5000
2
3
5 001 – 20 000
4
> 20 000
Sewerage Treatment Plants
4 50 meter
Volume 4
Location
Inlet Works or Entrance Inlet Works and Treatment Process Unit Every Internal Corner of STP boundry and nearby to Inlet Works, Treatment Process Unit and Sludge Treatment Entrance, Inlet Works, Mess Building, Process Treatment Unit, Secondary Treatment Unit and Sludge Treatment. 161
Requirements for Ancillary Facilities Facilities Requirements for Ancillary
Figure 6.9 Typical Details of Compound Lighting Figure 6.9 Typical Details of Compound Lighting
250
290
6000
105
105
670
STANDARD GALVANISED STREET LAMP POST
FRONT VIEW
SIDE VIEW
LAMP POST
6.11
6.12
6.11
Sampling Facilities Sampling Facilities
Suitable sampling facilities shall be provided (preferably in the form of Suitable sampling facilities shallthe be boundary provided (preferably form of an an open chamber) within of the STP in to the allow representative open samples chamber)towithin the boundary theperson. STP toFor allow representative be taken safely by ofone treatment plants up to samples to be taken safely by one person. For treatment plants up to 20 000 PE, sufficient space shall be allowed for proper preparation 20,000of PE, sufficient proper preparation samples to bespace takenshall awaybetoallowed central for laboratories for furtheroftesting samples to be taken away to central laboratories for further testing and space and analysis. The sampling area shall contain sufficient bench analysis. sampling contain bench space and than and The storage spacearea for shall samples. Forsufficient treatment plants greater storage space for samples. For treatment plants greater than 20,000 PE, 20 000 PE, the sampling area shall be provided in accordance the with MS sampling shall ladder be provided withsampling MS 1228. Access where 1228.area Access shall in be accordance provided for facilities ladder shall be provided for sampling facilities where necessary. Internal necessary. Internal surface area for sampling point shall be tiled with surface area for sampling point shall be tiled with clear coloured tiles clear coloured tiles
6.12
Auto Restart Facilities Auto Restart Facilities All electrical equipment shall be fitted with auto restart facilities for quick All electrical equipment be fitted with auto restart facilities for re-operation in the event of failureshall of power facilities. quick re-operation in the event of failure of power facilities.
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Requirements for Ancillary Facilities
6.13
Safety Facilities Safe access and walkways shall be provided at all process units and equipment (valves, penstocks, aeration tanks, etc.) that require service and maintenance. Safety handrails shall also be installed at walkways and other working areas with a fall greater than 2 m. Typical details of hand rail are shown in Figure 6.10 All chemical storage facilities shall be provided with a safety shower and eyewash as well as appropriate warning signs. Liquid chemical storage facilities shall be bund. Access to the area shall be restricted using lockable doors/gates. Provision for fire detection, alarm and fire fighting equipment shall be complying with the latest requirements in the Uniform Building Bylaws, the Institute of Electrical Engineers (IEE) guidelines and other statutory requirements. All tanks shall not exceed 1.2 m above ground. Stair case and ladder exceeding 1.2 m shall be provided with handrail All plants located adjacent to earth slopes shall be provided with proper slope protection structures. The slope protection design must be certified by Qualified Professional Engineer.
6.14
Doors All external doors shall be of weather proof and suitable for out-door installation. Door with sufficient width for the manoeuvre of equipment shall be provided at the building of pump station, blower room, etc. For opening more than 4 m wide or 5 m high, motorized roller shutter shall be provided complete with manual over-ride button, which enables it to be operated during power interruption.
6.15
Fire Hydrant For treatment plants above 20 000PE, fire hydrant shall be provided complying with the requirements of Jabatan Bomba.
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Requirements for Ancillary Facilities
6.16
Power Supply Power supply shall be provided to each plant from the approved source. Drawings submitted for approval shall indicate the locations of electrical power tapping point and schematic layout plan. Approval for power supply tapping should be obtained from relevant authority for permanent power supply before submitting inspection form. All related document, such as electrical bills, transfer of ownership: to be submitted before final inspection. Requirement of power shall be finalised prior to obtaining design approval Requirement of incoming permanent power supply shall be inline with Section 4 this Volume.
6.17
Internal Sanitation (Toilet) All plants shall be provided with toilet. The toilet shall consist of water tap, water closet, shower and wash basin. The area for toilet shall comply with Uniform Building By Laws. Toilet to be located beside the control panel building. Toilets can also be located in the mess or office building.
6.18
Lifting Requirement Safe lifting weight in unrestricted area is 16 kg. For heavier objects and/ or very tight locations, provision of crane or access for truck mounted crane to be made. Lifting requirements are as follows: - -
-
164
Weight < 16 kg: Manual lifting 16 kg ≤ Weight ≤ 250 kg: A davit or ‘A’ frame shall be arranged to allow items lifted by using manual chain hoist to be projected on a 1.2 m truck tray and positioned at 2 m above road level. In the pump station, motorized hoist is required for lifting weight exceeding 100 kg. Weight > 250 kg: A gantry with motorised hoist shall be arranged to allow items to be projected on a 1.2 m truck tray and positioned at 2 m above road level truck tray. Volume 4
Malaysian Sewerage Industry Guidelines
Requirements for Ancillary Facilities
Lifting equipment shall be subjected to DOSH approval standards and guidelines. Safe Working Load with approved method of installation shall be rated and printed for all lifting facilities. Height and lifting method must be considered in the design for Safe Working Load of lifting facilities. All portable motorised hoist shall be of 230 V operating voltage and fixed electrical hoist shall be of 415 V operating voltage.
All fixed 3 axis type gantry shall come with additional safety features such as travel stop limit switch, hoist over run limit switch, slow & fast speed mode and emergency stop (for all type of hoist). All fixed type outdoor lifting facility futures shall comprise of hoist parking bay with shade. All fixed type lifting facility shall come with working platform and excess ladder. Typical drawings of lifting davits and A-frame lifting facilities are shown in Figure 6.11 and Figure 6.12.
6.19
Ventilation Ventilation is the process of letting in outside air into a space so that it mixes with the inside atmosphere to dilute contaminants and replenish oxygen. The purpose of ventilation in a sewage treatment plant is to provide a comfortable and safe working environment for all plant personnel. Hence proper ventilation shall be provided as a mean of providing sufficient fresh air and reducing poisonous or explosive gases in enclosed or semi-enclosed spaces where access to human is allowed. Ventilation can be achieved naturally or mechanically: •
Natural ventilation uses the force of nature such as air currents, breezes, thermal gradients and pressure differences to move air in and out of the space.
•
Mechanical ventilation uses fans and blowers to force air through space. It is also sometimes called forced ventilation.
Particular requirements are: a)
Ventilation shall be intrinsically safe with respect to explosive gases (such as methane) where such gases may be present.
b)
Ventilation shall be designed to deal with the different densities of the various gases.
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Requirements for Ancillary Facilities
c)
d) e) f) g) h) i) j)
166
Ventilation fans shall be located outside the enclosed space to induce forced air into the plant. Intake locations shall be such that only fresh air is drawn into the system and not air recirculated from the exhaust. Mechanical ventilation shall be used if the system is required to remove contaminants. Ventilation exhaust shall be directed to a suitable location for discharge and it shall not be adjacent to the intake point.
Ventilation at rooms where heat generation may take place must be adequate to dissipate the heat generated to ensure a comfortable making ambient for the equipment and the operator. Noise levels associated with operating fans and blowers, particularly in a confined space, shall conform to the requirements in Section 4 of this Guidelines and other stationary requirements. Optimise recurring cost for operation, maintenance and replacement. Regular testing and inspection of the equipment
Compliance with the suggested ventilation requirements. Table 6.4 presents some commonly used values for ventilation rates in typical enclosed spaces of a sewage treatment plant: -
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Malaysian Sewerage Industry Guidelines
Requirements for Ancillary Facilities
Table 6.4 Space
Common ventilation rates
Minimum Ventilation Rate (Air Changes/hour, ac/hr)
Remarks
Wet-Well
30 intermittent 12 continuous
Dry-Well
30 intermittent 12 continuous
Grit Removal/ Screen Area
30 intermittent 12 continuous
Same as wet well
Digester Gas Control Room
30 intermittent
Same as wet well
Sludge Gas Compressor Room
30 intermittent
Same as wet well
Enclosed Grit Loading Areas
30 intermittent
Same as wet well
Enclosed Primary Sedimentation Tanks
30 intermittent
Same as wet well
Scum Concentration Tank
30 intermittent
Same as wet well
Chlorine and Sulphur Dioxide Rooms
60 intermittent
Hazardous areas, toxic fumes, floor level exhaust required. Interlock fans with manual switches located at each entrance. Also interlock fans with chlorine and sulphur dioxide detection. Use 100% outside air
Filter/Dewatering Area
12 continuous
Consider odour control for exhaust air from dewatering area, where warranted
All other enclosed unit processes not mentionedelsewhere
30 intermittent
In particular at blower room, high tension room, low voltage room, switchboard and control panel rooms, where there are tendency of heat generation
Sewerage Treatment Plants
12 continuous 12 continuous 12 continuous 12 continuous 12 continuous 12 continuous
12 continuous
Volume 4
Use 100% outside air. Step up to 24 ac/hr if hazardous gases are detected. Consider odour control, where warranted
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Requirements for Ancillary Facilities
k) l) m)
6.20
An audible and visible warning shall be provided at all entry points. This shall automatically operate if the fan fails. Where natural or forced ventilation is provided, it shall be installed in such a manner so as to avoid any ingress of water due to rain or other sources.
In areas with routine entry by personnel, the ventilation strategy shall emphasize adequate control of contaminants and the ventilation system shall be continuously operated.
Process Water The designer is encouraged to provide recycle water facilities from the treated effluent. The recycle water can be utilised for cleaning and landscaping purposes.
6.21
Aesthetic The structure of a treatment plant shall blend with the surrounding development to improve the aesthetic value of the area. Roof, structure wall or brickwall fancing can be designed with other than conventional finishing.
6.22
Close Turfing Unpaved area within the STP reserve shall be turfed with close turfing. The type of grass must be “cow grass”. For slope area, turf must be pegged to avoid grass wash away during water run-off.
6.23
Standard Roofing and related requirement Roof for control panel shall be of flat roof and shall be installed with water proving material on the final layer. The slope of flat roof shall be 1: 20 and gutter shall be provided. However, for the aesthetic purpose Pitch type roof may be provided. The slope shall be 30 degree from horizontal. Suitable material for roof such as roof tile is recommended. The design of roof shall be considered from the following: i) ii)
Suitable material for roof (flat or slope) including colour Adequate air for ventilations
iii) Enough heights for lifting facilities
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iv) Enough heights for access and headroom v)
Type of insulation
vi) Acoustic treatment where applicable
6.24
Painting Painting shall include all plant and machinery inside buildings, including pipework, grating, handrailing, internal walls below ground level and all metal work including machinery. The conduits and piping shall be appropriately named and labelled indicating flow directions and painted with the following colour codes for easy identification: Chlorine line
-
yellow with double green bands
Fuel gas line
-
orange
Compressed air line
-
Potable water supply line Raw sewage line
Final effluent line Sludge line
Non-potable water line
Other disinfectant lines Biogas line
-
-
- -
-
- -
green blue
black grey
brown
blue with double black bands
yellow with double red bands yellow
The labels shall be stencilled on the piping in a contrasting colour with the colour coded bands, if any, located at appropriate and strategic points. Colour codes selected for general equipment, building and others items in a sewage treatment plants shall be adhered to colour standards as detailed in Table 6.5. The types of paint and surface preparation used shall be as recommended by the paint manufacturer.
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Table 6.5 Painting System Index – Colour Standards Item
Colour
Equivalent Colour Guide
General Equipment including motors Dark Blue (unless come with the original manufacturer approved colour code)
Dulux Regal Blue 0013
Penstocks/Valves/Manhole Covers
Black
Par Bituminous Black
Machinery Guards/Railings/Runways/ Overhead Cranes/Lifting Davit
Yellow
Dulux Lemon 2024
Switchboards
Light Grey
Par Mandarin Blue 0013
Par Golden Yellow Dulux Pewter 695 Par Willow Grey 00A05
Fencing poles/Gates
Green
Dulux A365-13449 Par Green 3666
Building and Walls – Exterior
Grey (Weathersheild)
Dulux BS 00A0510235
Building and Walls - Interior
White
Fencewall – Interior and Exterior
Grey
Dulux BS 00A0510235
Floors - Concrete Interior
Green
Leigh Green 3666
Building Stripes
Green
Dulux A910-13448 Par Green 3666
Blue
Dulux A910-11482 Par Blue 2686
Indah Water Logo (where applicable)
Indah Water Green
Dulux A365-13449 Par Green 1006
Indah Water Blue
Dulux A365-11483 Par Blue 1007
Notes: The above painting requirements are not applicable to stainless steel, aluminium, galvanised metal surfaces except where necessary to comply with statutory health and safety requirement.
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Figure 6.10 Typical Detail of Guard Rail
Typical Details og Guard Rail
550
Figure 6.10
1
1100
21/4
150-250
100
33
SIDE PALM BASE TYPICAL RUN OF HANDRAIL AS VIEWED FROM WALKWAY SIDE FLAT BASE
550
TUBULAR STANDARDS
1100
1 21/4
150-250
100
12
TYPICAL RUN OF HANDRAIL AS
100
36
TRIANGULAR BASE
VIEWED FROM WALKWAY SIDE ROUND BASE TUBULAR STANDARDS
3000 C/C
550
1100
550
3000 C/C
DETAIL OF HOT DIPPED G.I. RAILING
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Requirements for Ancillary Facilities Requirements for Ancillary Facilities
Figure 6.11 Typical Detail of Lifting Davit 6.11 : Typical Detail of Lifting Davit 50
90
0
50
75
Requirements for Ancillary Facilities
25 25
25
20
20
FL
FL
30
450
6
6.11 : Typical Detail of Lifting Davit
30°
120
10
6 FILLET WELDED 50
OD=98
0 90 PLAT THICKNESS 10 75
SAFE WORKING LOAD TO BE INDICATED
50
25
260
250
1775
25
30°
25
20
20
FL
30
450
6
FL
120 DETAIL `A'
10
6 FILLET WELDED OD = 118 OD=98
SAFE WORKING LOAD TO BE INDICATED
DETAIL `A'
PLAT THICKNESS 10
SECTION LIFTING DAVIT
250
1775
260
SIDE VIEW LIFTING DAVIT
NOTE : DEPTH OF SLEEVE SHALL VARIOUS WITH HEIGHT OF POLE ACCORDINGLY
DETAIL `A'
Figure 6.12 : Typical DetailDETAIL of A`A'Frame Lifting Facilities
OD = 118
SECTION LIFTING DAVIT
SIDE VIEW LIFTING DAVIT 2160
1200
1800
203x203x46Kg/m UB
NOTE : DEPTH OF SLEEVE SHALL VARIOUS WITH HEIGHT OF POLE ACCORDINGLY 180
Figure 6.12 Typical Detail of A-Frame Lifting Facilities 315
203x133x25Kg/m UB
203x133x 25Kg/m UB
2340
2160 1800
203x203x46Kg/m UB
180
1200
2340
Figure 6.12 : Typical Detail of A Frame Lifting Facilities
315
203x133x25Kg/m UB
203x133x 25Kg/m UB 300x300x12 PLATE BOLTED TO CONCRETE
300x300x12 PLATE BOLTED TO CONCRETE
1500 TO PROVIDE WITH ROLLER OR FIX TO THE CONCRETE FLOOR (TO SYSTEM SUPPLIER DESIGN)
2340
2340
TO PROVIDE WITH ROLLER OR FIX TO THE CONCRETE FLOOR (TO SYSTEM SUPPLIER DESIGN)
SIDE VIEW
FRONT VIEW A-FRAME WITH I-BEAM
A-FRAME WITH I-BEAM
300x300x12 PLATE BOLTED TO CONCRETE
300x300x12 PLATE BOLTED TO CONCRETE
1500 TO PROVIDE WITH ROLLER OR FIX TO THE CONCRETE FLOOR (TO SYSTEM SUPPLIER DESIGN)
TO PROVIDE WITH ROLLER OR FIX TO THE CONCRETE FLOOR (TO SYSTEM SUPPLIER DESIGN)
FRONT VIEW
SIDE VIEW
A-FRAME WITH I-BEAM
A-FRAME WITH I-BEAM
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Section 7 Special Requirements
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7.1
Temporary Treatment Plants
7.1.1
Definition
Temporary treatment plants refer to STP that are built to operate on a temporary basis. The sewage will eventually be diverted to a centralised sewerage system. After then, the temporary treatment plant will be decommissioned.
There are 2 categories of temporary treatment plants:
Category 1 For temporary treatment of sewage during the upgrading of an existing sewerage treatment facility
Category 2 For temporary treatment of sewage during initial stage of a new housing development where it is not feasible to construct a plant of ultimate capacity during initial stage or it is located within the catchment of a centralised sewerage system.
7.1.2
Category 1: Temporary Treatment Plant for Upgrading of Facilities
During the upgrading of an existing treatment plant, the sewage flows into that plant shall be directed to a temporary treatment plant for treatment before discharge. The treatment process of the temporary plant shall be designed and calculated based on: the duration of the project, total existing flow and the compliance requirements. The temporary treatment shall be monitored at regular interval. Approval from the Commission and DOE must be obtained prior any direct discharge of the untreated sewage into the receiving watercourse. The temporary treatment plant shall be located within the compound of the existing site. The temporary treatment plant shall not be built on other site area unless approval is granted by the Commission
7.1.2.1
Compliance Standards for Category 1 Temporary Treatment Plants
Category 1 temporary treatment plant shall comply with the requirements as stipulated in this Guideline and shall be operated and maintained to the satisfaction of the Commission and the Director General of the Department of Environment (DOE) at all times.
The temporary treatment plant shall be designed to comply with the following minimum effluent requirements:
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a)
b)
Standard B for STP located downstream of water intake points and non-water catchment zones Standard A for STP located upstream of water intake points
The above levels shall be interpreted as ‘absolute’ pollutant levels. Final effluents will be monitored over the life of the temporary plant. A license to contravene shall be obtained before the construction of any temporary plant and the commencement of any upgrading works. The temporary plant shall incorporate provisions to minimize adverse impacts such as visual, noise, odour nuisance etc. to the surroundings. 7.1.2.2
Process Requirements for Temporary Treatment Plants Alternative or innovative designs may be used for temporary plant to meet the general design compliance as stipulated above. Unit processes within the temporary treatment plant can be designed to absolute standards. For example, a Standard A the effluent level of temporary treatment plant of this category can be designed to 20 mg/l BOD and 50 mg/l SS. Materials for construction can be of semi-permanent installation such as fiberglass tanks, mild-steel with epoxy coat, etc.
7.1.2.3
Operation of Temporary Treatment Plants During the upgrading of an existing plant, the project proponent shall appoint a class license to operate and maintain the temporary plant. If the upgrading contractor is a licensed operator, they may be appointed as the operator of the temporary plant.
7.1.3
Category 2: Temporary Plants for New Housing Development I)
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Multiple Phases Hosing Development
Temporary plant shall be provided for multiple phases housing development where it is not feasible to construct a plant with ultimate capacity during initial stage.
STP reserves must be located as far as practicable from habitable buildings. The needs of a temporary plant in a multiple phases housing development project depend on phases of development, size of each development phase, location of initial development and duration of the phase lag and entire development plan.
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The project proponent will construct a temporary treatment plant in compliance with the following criteria:a)
b) c)
(II)
Temporary plant will be decommissioned by the developer within time frame agreed between the Commission and the developer. Implementation program for ultimate plant is confirmed in accordance to an approved catchment study.
All temporary plant shall remain as private plant and shall be operated and maintained by a licensed operator appointed by the project proponent. Future Connection to Centralised STP
This applies to a catchment where implementation program to construct a centralised STP is approved but the completion date could not meet the project proponent’s needs. Under such circumstances, the project proponent may be allowed to build a temporary treatment plant. 7.1.3.1
Provision of Land for Temporary Treatment Plants The owner will be required to allocate land within the housing development for the construction of all temporary works. However, the site of the temporary treatment plant shall not be located on future public amenities land. The project proponent of the temporary treatment plant will be required to construct the temporary sewer reticulation within the development to convey sewage to the temporary treatment plant. At the same time, the project proponent must also construct the permanent sewer reticulation for the connection to the permanent plants or the centralised sewerage system.
7.1.3.2
Compliance Standards for Temporary Treatment Plants This category of temporary treatment plant shall comply with the requirements as stipulated in this Guideline. The plant shall also be maintained to the satisfaction of the Commission and the Director General of the Department of Environment (DOE) at all times. The temporary treatment plant shall be designed and maintained to comply with the following minimum effluent requirements: a) b)
Standard B for STP located downstream of water intake points and non-water catchment zones. Standard A for STP located upstream of water intake points.
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7.1.3.3
Process Requirements for Temporary Treatment Plants Temporary treatment plants shall be designed to the requirements set out in Sections 3, 4 and 6 of this volume. An alternative design may be considered for the temporary treatment plant that will be decommissioned within time frame agreed between the Commission and the developers. Materials for construction can be of semi-permanent installation such as fiberglass tanks, mild-steel with epoxy coat, etc. Filter systems may use refurbished filter material that meet the relevant standards. However, other equipment used within the works shall be new. Second-hand equipment is strictly prohibited.
7.1.3.4
Operation of Temporary Treatment Plants Temporary plant shall remain as private plant. The owner must appoint a licensed operator to operate and maintain the plant. Temporary treatment plants shall strictly comply to the requirements as stipulated by this Guideline and shall be operated to the satisfaction of the Commission and the Director General of DOE at all times. Temporary treatment plants shall be designed and constructed so as not to present any nuisance in terms of odour, noise, safety and visual impact to the nearby community.
7.1.3.5
Ancillary Requirement of Temporary Treatment Plants Temporary treatment plants shall be provided with proper security fencing in compliance with Section 6 of this Volume. Adequate access roads and drainage shall be provided. Landscaping of treatment plant shall be provided for better aesthetic value surrounding the plant.
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7.2
Treatment Plants Located Within Buildings
7.2.1
Introduction The installation of treatment facilities within buildings whether occupied or not, including basements of buildings, are not desirable and will not normally approve. Every effort must be made to come up with an alternative site or an arrangement to connect to a public system. Owners must resolve these issues at an early stage of the planning process. The Commission should be contacted early to establish if an alternative option is feasible. If approved, such installations will be subjected to stringent service condition requirements for the following criteria: a)
Access
c)
Electrical requirements for lighting system
b) d) e) f)
g) h) i) j)
Ventilation Noise control Process type Inlet works
Pre-treatment Confined space safety Odour Control
Discharge systems
k)
Flood mitigation measures
m)
General safety and health
l)
Operation and maintenance
n)
Sludge handling
o)
Sanitary and plumbing facilities
p)
Fire Fighting Equipment
Treatment plants within buildings will be considered as private treatment plants subject to eventual phasing out and replacement by a centralised system.
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7.2.2
Specific Guidelines and Requirements The specific guidelines and requirements for the criteria specified in 7.2.1 are listed below. I)
Access
a)
Vehicle access must be provided from the nearest public highway.
b) c)
d)
Parking space for a desludging and service vehicle must be within operating range. Access must be continuously available and unobstructed. Accessible to water and electricity supplies.
e)
Sampling point to be available for final effluent.
g)
Provision must be made for lifting of heavy equipment.
f)
h) II)
Allowance must be made for installation and removal of equipment. Suitable arrangements must be made for service and repair of equipment. Ventilation
Ventilation design shall be in compliance with the requirements in Section 6 and the specific requirements listed below: a) b) c)
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Suitable system must be provided to address poisonous, explosive and lack of oxygen conditions. Separate and independent (from the basement) ventilation must be provided for the confined spaces. Ventilation shall be of forced mechanical type.
d)
Ventilation must be intrinsically safe with respect to explosive gases such as methane.
e)
Ventilation must be designed to deal with the different densities of the various gases.
f)
Ventilation fan must be located outside the enclosed space to induce forced air into the plant. Intake locations shall be such that only fresh air from outside the building id drawn into the system and not air re0circulated within the building.
g)
Ventilation exhaust must be directed outside the building for discharge. Volume 4
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h)
Ventilation air exchanges shall be as follows:
Intermittent: Minimum of 30 complete air changes per hour ii) Continuous: Minimum of 12 complete air changes per hour A backup fan must be provided in the event of duty fan failure and must be automatic on entry. i)
i) j)
A petrol driven generator with an auto restart facility must be provided to continually operate the ventilation system in the event of power failure.
III)
Electrical Requirements for Lighting System
a)
Only high-intensity, low-voltage discharge lamps to be used for floodlighting of plant area during operation and maintenance.
b) c) d) e)
The lighting and electrical equipment must be both vapour and explosion proof.
A separate housing must be provided for electrical controls to prevent electrical sparks from coming into contact with flammable and explosive gases. All electrical equipment must be water proof against submersion.
Standby generators must be provided to allow the plant to operate independently of the mains supply.
IV)
Noise Control
a)
Adequate dampening of noise must be provided to meet minimum stipulated requirements by the local Building By-laws, DOE and/ or other regulatory bodies. Silencers and acoustic enclosures shall be provided where required to achieve the stipulated noise level reduction.
b) c)
d)
Noise control measures shall be implemented to control the generated noise level to below 65 dB at a distance of 2 m from the boundary of the housed noise source.
General noise levels (measured in decibel units) must also be measured 10 m from any point of the plant site within the nearest public space or occupied space or both to an acceptable level stipulated by the regulator. Enclosures used to achieve these noise reductions shall permit ready access to equipment for routine maintenance. Adequate air ventilation shall be provided to allow cooling of the air inside the enclosure to prevent over heating of the equipment/motors.
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V)
Process Type
The type of treatment process must be limited to systems that are easy to operate and maintain for reasons of: a) b)
lower sludge yield and more stable sludge characteristics lower operational and maintenance requirements
VI)
Inlet Works
The design shall incorporate some means of controlling the influent velocity to prevent: a) b) c) d)
excessive wear due to scouring effects excessive head loss in the inlet uncontrolled overflow of raw sewage release of sewer gases
VII)
Pre-treatment
a)
The design must include a macerator to i) ii)
b) c)
reduce toilet waste and large solids into smaller and finer particles, reduce the quantity of screenings
iii) improve the ease of handling.
Screening must be provided at 10 to 12 mm clear spacing to remove fine particles. A combined grit and grease removal system must be provided.
VIII) Confined Space Safety a)
Operators must: i) ii)
b) c) d)
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attend a recognised confined spaces training course, obtain training certificates, and
iii) be certified competent to operate in such an environment.
Confined space areas within the plant site must be clearly identified before handover for operation. Confined space areas must be demarcated and warning notices placed. Confined space procedures must be established and followed by operatives.
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e)
The following must be provided: i) ii)
f)
gas detection equipment, preferably electronic, and serviced regularly
The design of the treatment plant shall be subject to a Hazard and Operability Review (HAZOP) exercise to identify and reduce the potential risks under the following scenarios: i) ii) iii) iv) v)
g)
rescue sets of breathing apparatus
electrical failure
blockage of inlet and outlet
equipment failure including lighting and ventilation blockage of any pipework
flooding of external discharge point
vi)
failure of building drainage system
i)
flooding
The consequences of such failures to operators may include: ii) iii) iv) v) vi) vii)
explosion drowning
falling into open voids asphyxia poison
nausea
IX)
Odour Control
a)
Isolate odorous gases from general ventilation exhausts by containing identified odour generating sources with a separate local exhaust system.
b)
Containment of the odour sources shall be by installing lightweight and corrosion resistant covers/enclosures designed for practical operation and maintenance works.
c) d) e)
The local exhaust odorous air shall be conveyed through well designed and balanced ductworks by a centrifugal fan to an effective odour treatment equipment. Odour treatment equipment shall be selected such that odours be reduced to the lowest possible level and in compliance with the EQA. The potential of odour generation, its impact and treatment, shall be considered in all aspects of design.
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Special Requirements
X)
Discharge Systems
Most basement plants will lie below the level of the running drain levels. Therefore, it is essential to: a) provide an effluent collecting sump prior to pumped discharge. b) provide a check valve at the end of the discharge pipe to prevent the backflow from the monsoon drain to the treatment plant. c) provide a 100% redundancy of the discharge pumping capacity. XI)
Flood Mitigation Measures
a)
Provision must be made for the isolation of the treatment plant from flooding by external sources.
b)
A sump pump shall be provided.
XII)
Operation and Maintenance Agreements
a)
All treatment plants installed in basements of buildings must be subject to an Operation and Maintenance Agreement. An example of the standard Operation and Maintenance Agreement is given in MSIG Volume 2.
b)
All treatment plants located within buildings must be operated by a fully licensed operator and will be subject to periodic checks by the Commission to ensure compliance.
XIII) Occupational Safety and Health a)
All treatment plants shall be designed to comply with the Occupational Safety and Health Act, 1994. Properly designed treatment plants will enable the operator to safely handle the treatment plant throughout its design life. A brief summary of the contents of Act 514 is attached in Appendix A.
XIV) Sludge Handling a) b)
c)
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An aerated sludge holding tank shall be provided to keep the sludge from going septic
Permanent pipe work with proper coupling and isolation valve should be provided adjacent to the access gate for easy coupling sludge tanker’s hose of hose for during desludging of the sludge holding tank. To provide sludge pump for desludging purpose.
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XV) a)
Sanitary and Plumbing facilities To provide stand pipe for cleaning purposes. Waste water to be channelled back to the inlet of plant.
XVI) Fire fighting system a)
To provide appropriate fire fighting systems in accordance to Fire Department and other statutory requirements.
7.3
Fully Enclosed Treatment Plant
7.3.1
Definition A fully enclosed plant is defined as a treatment plant that is designed such that their treatment unit processes are located within dedicated buildings. A fully enclosed plant is to be equipped with additional features and requirements to minimize adverse impact to the surrounding environment. Fully enclosed treatment plant shall comply with the following criteria: a) b) c) d) e)
Must be located within a dedicated sewage treatment site. Provide with appropriate architectural enclosures building. No unit processes shall be located outside the enclosed buildings/ architectural enclosures. Individual treatment unit process may be covered with a permanent structure or housed in an enclosed building. Provide appropriate landscaping to adequately screen the treatment plant from other developments in the vicinity.
Appropriate architecture style, landscaping, architecture surrounding the treatment plant and fencing type must be used. 7.3.2
General Requirements When approved, fully enclosed treatment plants must comply with the general requirements set out in Section 3, 4 and 5 of this Volume and also specific requirements in this Section 7.3 for the following: i) ii)
Provision of odour control Noise control and mitigation measures
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iii)
Minimize visual impact
v)
Enhance safety, health and operability
iv)
I)
Avoid aerosol effects
Odour Control
The potential for odour generation, its impact and treatment, shall be considered in all aspects of design. The range of odorous constituents in such biogenic odours is very wide and they include: hydrogen sulphide, ammonia, thiols and other organic sulfur compounds, amines, indole and skatole, volatile fatty acids and a wide range of organic compounds produced by anaerobic fermentation.
Particular problems can be found at: Inlet works, primary tanks, secondary treatment, sites for transfer, storage and treatment of raw sludges and leakages. A separate local exhaust system, for containment and exhaust of odorous air to treatment, will isolate such odours from the general ventilation system.
Odour treatment equipment shall be selected such that odour is reduced to the lowest possible level and in compliance with the EQA.
Containment, exhaust and treatment shall be designed as an integrated package.
II)
Noise Control
Adequate dampening of noise must be provided to meet minimum stipulated requirements by the local Building By-laws, DOE and/or other regulatory bodies. Silencers and acoustic enclosures shall be provided required to achieve the stipulated noise level reduction. Noise control measures shall be implemented to control the generated noise level to below 65 dB at a distance of 2 m from the boundary of the housed noise source. The general noise levels generated shall also be measured 10 m from any point of the plant site within the nearest public space and/or occupied space to an acceptable level stipulated by the appropriate regulators. Enclosures used to achieve these noise reductions shall permit ready access to equipment for routine maintenance. Adequate air ventilation shall be provided to allow cooling of the air inside the enclosure to prevent over heating of the equipments/motors.
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III)
Aerosol Effects
Aerosol is defined as a suspension of colloidal particles in gases/ atmosphere. Aerosol control measures are important because aerosol affects the human respiratory system. If uncontrolled, aerosol could present a health hazard to the operator and residents due to the reduced buffer zone around the treatment plant. Screens, open channels and aeration tanks, where violent and turbulent actions are encountered, may release aerosol. The design of the treatment plant shall take into consideration any unit processes that are likely to emit aerosol and mitigating measures shall be undertaken to counter aerosol release to the atmosphere.
IV)
Safety, Health and Operability
The design of a fully enclosed treatment plant shall address safety, health and operability aspects. The guidelines given for treatment plants located within buildings in Section 7.2 shall be followed. 7.3.3
Specific Requirements
I)
Covers for Treatment Unit Processes
The purposes of these covers are to contain odour emission at source and to reduce visual impact. The design requirements for treatment unit processes are outlined below. a) b)
c)
d)
Covers to contain odour emission shall be provided at all potential sources of odour generation for all unit processes located within the sewage treatment works.
Bins used for the storage of screenings and grit collected in the pre-treatment area shall be completely covered to reduce visual impact, odour and to keep vectors away. The designer shall provide further considerations on the size, type and method of emptying the bins. Generally, all unit processes shall be covered or housed within a building enclosure. This shall include all pre-treatment units, aeration tanks, and sludge treatment and handling facilities. The only exception is the secondary clarifier. The bin shall be located on a bunded, paved area adjacent to an access road to the treatment plant.
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Special Requirements
e)
f)
The cover shall comply with BS EN 124 if subject to loading. It shall also be designed to meet the operating condition of the odour extraction system as well as the location and application appropriation. If the cover is exposed to the environment, i)
ii) iii) g) h) i)
j) k)
Metal covers if used, must have appropriate corrosion resistant coating in accordance to Section 4 of this Volume.
Where chipping might occurs at the edge of the cover, stainless steel reinforcement frame on all sides of a plastic or FRP cover shall be provided.
Coatings for the concrete and steel shall include coal tar, vinyls and epoxies in accordance to Section 4. Covers should be hinged and weigh less than 16 kg to enable lifting unaided. Beyond a cover weight of 16 kg, assisted lifting is required.
All unit processes with covers or are housed in a building for odour and visual impact reduction shall be provided with proper air extraction and air scrubbing system. These devices shall be safe to operate and maintain. Odour, noise and visual impact, and aerosol are the major components for consideration in the design of an enclosed wastewater treatment plant. Windows and access hatches that give the operator an extended and uninterrupted view of the treatment process are mandatory for all unit processes that are covered. Covers shall be designed to allow for easy dismantling and easy access for cleaning of the enclosed plant.
The materials used for the cover structure depend on the type of cover selected and the characteristics of the odorous environment. In general, the materials shall be selected to provide durability, ease of maintenance, corrosion resistance and be relatively inexpensive. The three most common materials used for containing odours are concrete, aluminum and FRP. The design requirements for each of these are outlined below. i)
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Plastic or fiberglass cover if used, must be manufactured with UV inhibitor and will not warp or deform due to weathering effect.
Concrete
Concrete can support the greatest weight but limits the plant maintenance worker’s ability to remove the cover for major repairs. Concrete covers are subject to corrosion and should be treated with a protective coating, such as an epoxy resin.
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II)
ii)
Aluminum
Aluminum covers provide the greatest tensile strength with the thinnest cross-sectional area and can be placed on a light weight frame. The lightweight nature and thin crosssectional area of aluminum makes it easier to remove and store the covers during maintenance operations.
Aluminum covers are generally less expensive than FRP and concrete, but periodic maintenance in the form of an anodised coating is necessary to help prevent corrosion. The design of an aluminum cover shall consider the incompatibility of aluminum with concrete and other metals. If not, disintegration of the materials occurs and the structural integrity of the system could be jeopardized.
iii)
FRP
FRP is light weight and generally can be removed by plant operator and stored during maintenance operations. FRP covers also offer resistance to corrosion, but require periodic maintenance with an ultraviolet inhibitor to enhance durability, particularly, if exposed to sunlight on a prolonged basis. Ventilation system
Ventilation systems are required to supply fresh air for workers to work in a more comfortable environment and to minimise health and safety concerns. All covered unit processes must have proper ventilation systems. a) b) c) d) e)
An exhaust ventilation system shall be provided with air distribution patterns that effectively purge work areas.
For waste areas that workers must enter, both blowing and drawing air shall be used to eliminate dead spots. Areas designed for personnel entry must include relief systems to avoid overpressure conditions. Designers must estimate cover system leakage to determine fan capacity. Force air ventilation systems should be inspected and tested periodically to ensure proper air flow and air distribution.
Ventilation of enclosed plants can be either intermittent or continuous. However, intermittent ventilation is not recommended because it has a lower degree of safety and more difficult to operate and maintain than continuous ventilation. Continuous ventilation is typically more expensive to operate because of higher electricity costs for running the blowers. Intermittent
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f)
g)
h)
i) j)
ventilation typically requires a higher rate of ventilation. For example, the wet well and grit removal facility requires 12 air exchanges for continuos ventilation versus 30 air exchanges for intermittent ventilation.
The requirement in Section 6 shall be refer for the design of exchange rate. If the work site is classified as a confined space, workers without proper respiratory equipment must not occupy spaces that cannot be ventilated to less than 25% of the permissible exposure limit (PEL) of the contaminant and less than 10% of the lower explosive limit (LEL). For example, hydrogen sulfide which is one of the most common contaminants in enclosed areas exposed to wastewater has a ceiling concentration of 30 mg/m3 (20 ppm). Combustible alarms set at a percentage of the LEL and ventilation failure alarms should be installed in wet wells, screen rooms, or other enclosed areas where a volatile atmosphere could exist. These alarms must have both audible and visual indicators to alert workers that the area is now potentially dangerous as well as alerting those who are about to enter the problem area.
Before entering the enclosed plant, where there is potential for a hazardous atmosphere to exist, the operator and/or worker must be able to test for oxygen deficiency, and combustible and toxic gases or vapors. Ventilation systems shall be designed on the basis that the potential odourous gases have been isolated and contained by the local exhaust system for odour control. Ventilation design criteria for work space are as follows: i)
ii)
iii) iv)
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Avoid positioning supply and exhaust registers at equal elevations and on the same enclosure wall. This will prevent short-circuiting the ventilation system and creating dead zones (areas with no apparent ventilation or air motion). Equip the makeup air supply and exhaust registers with volume dampers to control the airflow rate. Makeup air supply should be less than what is exhausted to create negative air pressure within the enclosure. A duty and standby ventilation system are mandatory. The standby shall be 100% that of duty. An external visual indicator, such as green/red light, to be provided outside the enclosed plant to warn of ventilation systems failure.
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k)
The design of the ventilation system shall take into account the noise aspects. Generally, the design work shall include for sound insulating material, resilient mountings or other appropriate devices to ensure that the plant runs without noise or vibration in its final installed position. Noise level from machinery shall not exceed the level stipulated by the regulators.
III)
Odour Control System
a)
Isolate odorous gases from general ventilation systems by containment of identified odour generating sources with a separate local exhaust system.
b) c)
d) e) f)
g) h)
IV)
Containment of the odour sources shall be by installing lightweight and corrosion resistant covers/enclosures designed for practical operation and maintenance works. Local exhaust rates for containment shall be designed to provide a negative pressure, prevent build up of toxic, corrosive or explosive gases and include provision for process air or air displaced by changes in the level of liquid inside the covered space. The local exhaust odorous air shall be conveyed through well designed and balanced ductworks by a centrifugal fan to effective odour treatment equipment.
The overall performance of the odour control system shall comply with the requirements of the Department of Environment (DOE). In situations where specific gases such as hydrogen sulphide and ammonia are significantly present, consideration shall be given for the installation of a pre-scrubber unit upstream of the main odour treatment equipment. Effective odour treatment equipment to be a minimum 90% removal efficient. Consideration must be given to the life span of the odour control system and associated costs in operating and maintaining such a system. Vent Stack
The vent stack shall at a minimum 5 m above ground level to ensure sufficient dispersion of air. Where the stack is located adjacent to a building, it should be located at least 1 m above the roof line of this building.
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V)
Noise Level
All mechanical equipment that are likely to generate noise such as blowers, compressor and pumps, shall be acoustically isolated to ensure the noise generated are contained and reduced to below the levels stipulated by the regulators.
VI)
Sludge Handling
a) Due to the compactness of the site, it is not conceivable to have sludge drying beds in an enclosed environment.
Instead, an aerated sludge holding tank shall be provided to prevent the sludge from turning septic. Sand drying beds (either covered or otherwise) are not an acceptable form of sludge treatment in an enclosed plant.
b) Permanent pipework with female coupling and isolation valve should be provided adjacent to the access gate for easy coupling of tanker’s hose during desludge of the holding tank.
VII)
Treatment Process Type
It is preferred that treatment in an enclosed environment employs extended aeration activated sludge because it offers greater process stability and less potential for generating odours. However, other treatment processes warrant further considerations if proven that they have other distinct advantages in an enclosed environment.
VIII) Siting of Plant a)
b)
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The enclosed plant needs to be located away from driveways to allow for regular maintenance of the screens, grit and grease removal units and wet well of pump stations. If this is not possible, then bollards shall be erected to protect the workers while maintaining the plant. Where plants are located within the premise of a private property, direct vehicle access is to be provided from the public road to the plant via a gate in the perimeter fence.
IX)
Groundwater Conditions
a)
Adequate provision must be made to resist the uplift of the structure due to hydrostatic ground water pressures. The side and bottom walls shall be designed to withstand the anticipated hydrostatic pressures.
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b)
The top of the plant shall be located at least 150 mm above the finished surface level to prevent the inflow of surface run off into the enclosed plant.
c)
Good perimeter drainage is to be provided to ensure that the plant is not flooded.
X)
Installation and Removal
Installation and the subsequent removal of all mechanical and electrical equipment need to be taken into account during the design of the cover. The following requirements must be carefully catered for: a) b) c) d)
e)
XI)
Adequate space for servicing must be provided in the design of the enclosed plant.
If the installation and/or removal of the equipment require the service of a crane or any lifting vehicle, then access must be made available within the treatment plant for these lifting vehicles.
An adequate number of access covers and sizes of openings for the removal and installation of the equipment shall be provided.
The design of an enclosed plant must allow for the plant to be fully operational during the installation and/or removal of any equipment. Alternatively, provisions for temporary bypass should be accommodated to prevent disruption to the sewage flow while this work is being carried out. In situations where it is not possible to readily install a duty and standby unit, the standby unit can be supplied as a separate item which is kept in store, provided that the faulty unit can be removed and the spare unit can be installed within two hours by general maintenance workers using normal tools. Mechanical and Electrical Requirements
The wiring, lighting and other electrical or mechanical equipment and appliances that have the potential to generate sparks that may trigger an explosion shall be designed and installed to meet the relevant safety codes to avert the possibility of an explosion.
XII)
Building Plan Approval
If a building structure is used to house the enclosed treatment plant, then the design of this building must comply with the requirements stipulated by the relevant Building By-Laws.
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7.4
Covered and Buried Treatment Plants
7.4.1
Definition
Covered and buried treatment plants refer to treatment plants with covers that are placed below ground or not more than 1.2 m above ground level. Covers are provided to reduce the odour, noise and visual impact.
This type of plant is only applicable to Class 1 and Class 2 sewage treatment plant with treatment capacity no more than 5000 PE. Special approval by the Commission must be obtained if the plant capacity exceeds 5000 PE. A compromised buffer zone of 10 m minimum from the fence to the nearest building boundary line must be provided for this type of plants. However, the height of the structure is normally limited to 1.2 m above ground.
7.4.2
General
Covered and buried treatment plants have inherent hazard and restriction in operability in their actual operation and maintenance. The requirements in the following sections serve to highlight the minimum improvements that must be made to these plants in addition to those set out in Section 3, 4, 5 and 6 of this Volume.
7.4.3
Specific Requirements for Covered or Buried Plants of 5,000 PE or Less
I)
The design of these tanks must allow for adequate openings so that the operator can carry out routine operation and maintenance works in a safe, efficient and effective manner. These requirements apply to all unit processes that are covered or buried from the inlet works to the effluent chamber. Staggered square openings of roughly 600 mm x 600 mm employed in the past for plants of this nature would not be acceptable. These openings, as a minimum, must be opened top around the periphery of the tank.
II)
The designer must take into account the confined space and other related safety issues for entry into such a tank. Provision of proper access into each individual tank is mandatory. Where the depth exceeds 2.5 m, steps with intermediate landings must be included. Other requirements, such as adequate ventilation prior to tank entry, must be considered and provided in the design.
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Openings of Covered and Buried Tanks
Access for Routine Operations and Maintenance of the Plant
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III)
Pipework and Aeration System Requirements
Piping for buried plant shall be exposed and accessible for ease of maintenance. PVC pipes are not allowed. The aeration system (diffuser) must be retrievable from top opening without emptying the tank. VI)
Lighting
Adequate lighting must be provided through adequate opening at the top of these covered or buried tanks to provide a good view of the treatment process such as the air diffusion system, screening, degritting and secondary clarification. This is important for daily plant operations through visual inspection of the individual unit process and routine maintenance of the plant. V)
Hand Railings
Hand railing provisions must be made to prevent falling into open spaces. These hand rails must be provided on the perimeter of the open tanks and further enhanced with kick plates. VI) Desludging Activities Adequate access within the proposed treatment plant site is to be made available to allow for desludging tankers to be within the reach of the waste activated sludge storage tanks without undue difficulty of maneuvering the vehicle or damaging the buried tanks or pipe works. VII) Labeling of Treatment Unit Process Labeling of each treatment unit is to be provided, from the inlet works to the secondary clarifiers, to avoid confusion with the similar geometry and sizes used for most treatment units. VIII) Noise Control Due to the compromised buffer requirements and proximity to adjacent developments, the potential for noise pollution is accentuated. The designer must ensure all noise generating mechanical and electrical equipment within the treatment plant must be contained and treated acoustically to meet compliance to existing noise levels stipulated by the Department of Environment and that set out in Section 4. IX) Ventilation Adequate ventilation must be made available to allow for the safe routine operation and scheduled maintenance of the treatment plant. During
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Special Requirements
design, this ventilation aspect must be considered. The type of ventilation, portable or permanent, must also be determined during design stage. X)
Odour Control
Odour Control systems to be provided as required in compliance to the EQA. XI)
Buoyancy Effects
The designer must account for the buoyancy effects in the design of buried or covered tanks. This effect is of concern during high groundwater conditions and emptying of the tank content during desludging works. Furthermore, the designer must ensure that the design of these tanks accounts for the hydrostatic force exerted on the floor from the outside does not exceed the compressive strength of these covered or buried tanks. This is to prevent any breakthrough of the floor and subsequent failure of the tank. The designer must ensure that the design of these tank at worse case scenario where the tank is fully emptied. This is to prevent any breakthrough of the floor and subsequent failure of the tank. XII) Covers Covers if employed for odour, visual and noise impacts shall be subjected to the following requirements: a) Lifting may be unaided if the covers are hinged and weigh less 16 kg. b) Assisted lifting is required if the covers weigh equal to or above 16 kg. c) The cover shall comply with BS EN124 loading requirements. d) If the cover is exposed to the environment, i) Plastic or fibreglass cover if used, must be manufactured with UV inhibitor and will not warp or deform due to weathering effect. ii) Metal covers if used, must have appropriate corrosion resistant coating in accordance to Section 4 of this Volume. iii) Where chipping might occurs at the edge of the cover, stainless steel reinforcement frame on all sides of a plastic or FRP cover shall be provided. XIII) Fencing Adequate fencing must be provided for all plants. Adequate security shall be provided against unauthorised access. 196
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7.5
Guidelines for Homestead Developments
7.5.1
Single Developments up to 30 Units or 150 PE in Total
Individual septic tanks may be allowed for single developments of up to 30 units or 150 PE in total.
Septic tanks will be regarded as temporary treatment plants.
The owner must provide all septic tanks as part of the owner’s infrastructure works.
Septic tanks must be constructed to standard design in compliable with MSIG Volume 5.
7.5.2
Single Developments Over 30 Units in Total With Average Housing Density Greater Than Five Units per Hectare
For single developments over 30 units in total with an average housing density greater than 25 persons per hectare, a sewer reticulation and a communal treatment plant must be provided.
The treatment plant may be classified as permanent.
Sewer reticulation must be appropriately designed to achieve acceptable hydraulic conditions within topographic and routing parameters.
7.5.3
Single Developments Over 30 Units in Total with Average Housing Density Less Than Five Units per Hectare
For single developments over 30 units in total and with an average housing density of less than 25 persons per hectare, a sewer reticulation and a communal treatment plant is preferred.
The treatment plant may be classified as permanent.
Where the terrain of the development is such that if a communal system is constructed it will require the construction of too many intermediate pump stations, then individual treatment facilities may be considered, subject to the following conditions:
i)
ii)
The individual system must be a system approved by the Commission. Where the ground conditions permit, soakaway trenches must be used for disposal of the final effluent from the treatment systems.
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iii)
iv) v)
Developers shall ensure that home owners enter into an agreement with the supplier of the systems or licensed contractors, to carry out operation and maintenance of the system as per design requirements.
Tanks shall be desludged by the Service Licensee as per terms of the agreement signed between the Services Licensee and the Commission.
The Commission and DOE may impose stringent conditions, if they believe that such measures are required to ensure that the sewage from the development will not result in an adverse impact on the environment.
All septic tanks shall be designed in accordance with the requirements in MSIG Volume 5.
7.6
Non-Compliance with Standards
7.6.1
Introduction
This section describes the types of incidents, which are outside the control of the operator that may cause a sewage treatment plant to fail its effluent consent. Generally, the more sophisticated the treatment process, the more a process is at risk of failure from one of these incidents. It would be unreasonable to expect the operator of the treatment plants to perform within the effluent quality standards following such incidents. However, the operator must always use his best endeavours to rectify the situation as soon as practicable following such an incident.
The following potential incidents are treated as special cases when meeting absolute compliance with Standard A or Standard B.
7.6.2
Types of Incident’s that Can Cause Treatment Plant Failure I)
Power Interruption
An interruption in the power supply to a treatment plant will cause failure in all mechanical treatment processes. Some large treatment plants have emergency generators which can be brought on stream to ensure inlet pumping continues. However, the crude sewage will pass through the plant receiving only rudimentary treatment and will probably fail to comply with Standard A and Standard B. Furthermore, all existing sewage treatment plants have to be restarted manually once they are tripped through power failure.
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On new works, all treatment plants will be fitted with auto-restart facilities for immediate resumption of operation when power is reconnected. II)
Lightning
When buildings or cabinets housing electrical control equipment are struck by lightning, fail safe surge protection equipment trips all mechanical equipment. This requires all the equipment to be reset and switched on again. On an unmanned plant there will be a delay between the trip-out following the lightning strike and the operators getting to the plant to reset the equipment. During this period the plant may fail to comply with the relevant standards. III)
Storm and Flood
During periods of very heavy rain, areas of the local sewer network may suffer such ingress of storm water that surcharge of the sewer system will result, causing abnormally large flows to arrive at the STP inlet. Under these conditions, the treatment plant would receive much higher flows than that designed for and would suffer severe hydraulic overloading. The effect would be a rapid wash through of sewage and solids causing the works to fail to meet standards. IV)
Major Mechanical Breakdown
In many existing sewage treatment plants, particularly the small ones, insufficient standby equipment has been provided by the developer.
All new plants must be equipped with standby units having an automatic change over system in the event of failure. Existing plants may be out of action for several days while repairs are carried out to failed equipment. To help alleviate this problem, the operator needs to carry critical spare parts to help speed the repair process. V)
Vandalism, Theft and Criminal Damage
If a treatment plant is subject to this form of interference, then the treatment process is at risk until the necessary repairs are carried out. Reasonable measures must be taken to deter vandalism.
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VI)
Deliberate Discharge of Toxic Chemicals
From time to time, irresponsible industrialists may discharge chemical waste to the sewer in contravention of all the relevant legislation. This may occur as a one-off dumping exercise, or may be the result of a small continuous discharge from a trade process which affects the treatability of the sewage and causes the treatment plant to fail. VII)
Accidental Discharge of Substances
Strong Loads or Toxic
From time to time, genuine accidents occur on industrial premises or on the highway that result in abnormal discharges to the sewer. These may take the form of serious fires at industrial premises, the sudden failure of large storage tanks or a major traffic incident involving the transport of liquid products. Such discharges to the sewer system would almost always result in the sewage treatment plant failing to comply until the effects of the discharge have passed through the system. VIII) Major Blockages in the Sewer Network System A blockage in the main sewer network system often causes the sewage to build up behind the blockage and turn septic. The sudden release of this large volume of septic sewage by the clearance of the blockage, may cause temporary overloading of the treatment plant and lead to a reduction in effluent quality beyond the absolute standard for a short period of time. IX)
Defect
Completed treatment plant to be inspected by competent personal. Visual inspection to be conducted during the final stage of construction. Two type of defect generally detected during inspection :
200
a)
Minor Defect
b)
Major Defect
Non-critical, do not immediately or unduly affect the performance of the plant but nevertheless, require attention to rectify faults within reasonable time frame. Critical or serious and require immediate action to be taken in rectifying faults, impair plant performance, unit processes, or system components.
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Consultant’s responsibility to ensure compliance of the design standard and good engineering practice.
7.7
Energy Saving
In selection of treatment process or equipment, the designer should consider the best product which minimized the power consumption for process and major plant equipment without compromising on the quality of treatment discharge.
7.8
Recycle and Reuse
a)
b)
c)
To promote/encourage designer to look into potential of energy reuse. To utilize the recycle water (reclaim water) for cleaning and landscaping purposes,
To promote and encourage design to identify potential of sludge reuse and/or recycle.
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Section 8 Package Sewage Treatment Plant
Package Sewage Treatment Plant
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Package Sewage Treatment Plant
8.1
Definition
A package sewage treatment plant is a form of treatment plant both for fixed film and suspended growth processes. It shall consist of a prefabricated biological treatment system and be limited to the development of the sewage treatment system between the ranges of 150 to 5000 populations equivalent (PE).
The package sewage treatment plant is only applicable to Class 1 and Class 2 STP as defined in Section 4 of this Guidelines. The prefabricated biological treatment system shall have been given approval by the Commission prior to the application.
The major components of a package sewage treatment plant are: I) a) b) c) d)
Inlet works Primary screen. Pump Station (if applicable). Secondary screen. Grit and grease chambers.
II) a) b) c) d) e) f)
Biological treatment system Balancing Tank. Aeration/Anoxic Tank. Clarifier. Sludge Holding Tank. Aeration System including blower house. Sludge Dewatering System.
III)
Outlet works
a)
Disinfection that can be physical, chemical or radiation.
Package sewage treatment plants fall under the category of covered/ buried treatment plants.
8.2
Land Area Requirement The land area requirements for package sewage treatment plants shall comply with those recommended for Class 1 and Class 2 Plants in Section 2 of this Guidelines. The net area does not include the 10 m buffer zone surrounding each plant, but does include the 5 m set backs and access paths within the plant.
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8.3
Design Requirement a) b)
All calculations regarding the inlet works, outlet works, biological processes and hydraulics shall follow the design criteria as stipulated in the Section 4 and Section 5 of this Guidelines.
All units of package sewage treatment plant and foundation shall be designed to meet the extreme case scenario as follows: i)
c)
d) e)
ii)
When the tanks are fully emptied;
During high groundwater conditions.
The structural design of a tank shall consider all factors that can affect the strength and integrity of the tank, like soil conditions, area of installation, etc. All tanks shall be structurally designed to withstand the maximum earth load and hydrostatic pressure equivalent to a backfill depth of 1 m.
All civil works of blower house, pump house and control panel room shall be as recommended in Section 4 and 5 of this Guidelines. The minimum design life span of the components of the package sewage treatment plant shall be as Table 8.1 below:
Table 8.1 Minimum Design Life Span of Package Sewage Treatment Plant Components Component
Prefabricated tank and other structural components Civil
Mechanical & Electrical
Design Life Span
> 50 years > 50 years 10 years
8.4
Components of Package Sewage Treatment Plant
8.4.1
Layout, Piping and Arrangement of Prefabricated Biological Treatment System The prefabricated biological treatment system shall be packaged in terms of layout, piping, arrangement of the tanks and the biological processes. The dimension of each tank shall be fixed for each model of the prefabricated system. All these items shall not be changed once approved.
8.4.2
Prefabricated Tanks The physical properties of the tanks for package plants shall meet the material requirements for STP structures as stipulated in Section 4 of this MSIG. The prefabricated tanks shall come as complete tanks, thus no
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Package Sewage Treatment Plant Package Sewage Treatment Plant
8.4.2
8.4.3
8.4.3
Prefabricated Tanks welding, jointing, fabrication/moulding of tanks’ components is allowed at The site. physical The routeproperties for delivery of tanks tanks shall be planned so as of the for package plantsproperly, shall meet the notmaterial to cause any damage to road facilities and harm to road users. requirements for STP structures as stipulated in Section 4 of this MSIG. The prefabricated tanks shall come as complete tanks, thus no Process Units/Components welding,Treatment jointing, fabrication/moulding of tanks’ components is allowed at site. The route for delivery of tanks shall be planned properly, so as not to The following table provides the recommended number of tanks for each cause any damage to road facilities and harm to road users. unit process against the PE size. The effective volume consideration is also incorporated in the Units/Components table. Process Treatment
The following table provides the recommended number of tanks for each unit process against the P.E size. The effective volume consideration is also incorporated in the table. Table 8.2 Recommended Number of Tanks and Effective Volume Table 8.2: Consideration Recommendedfor Number ofUnit Tanks and Effective Volume Various Processes Consideration for Various Unit Processes Max Number of Tanks PE ≤1 000
Max Number of Tanks Tanks PE >1 000
Aeration Tank
2
4
Anoxic Tank
2
4
Clarifier
2
4
Sludge Holding Tank
2
4
Name of Tank
Balancing Tank
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Effective Volume
2
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Note:
Low water level (LWL) is the minimum submergence level of the pumps to protect it from damage. It is dependent on the type of the pumps, thus the low water level shall be set according to the pump’s manufacturers requirement Top Water Level (TWL) is the normal operating water level with adequate freeboard provided.
8.5
Appurtenances
8.5.1
Piping system
8.5.1.1 General a) b) c) d) e) f) g)
The piping used shall be an approved product, supplied and manufactured by a supplier/manufacturer approved by the Commission and shall be suitable for the application. The arrangement of the piping system and interconnection pipes in the tanks shall not obstruct maintenance work of the equipment in the tanks. All the buried piping shall be properly bedded and supported with the selected compacted fill material.
All the above ground piping shall have a minimum distance of 75 mm from the ground level. It shall be provided with a proper pipe support and bracket. The bracket shall be made of hot dipped galvanised steel.
The arrangement/layout of the above ground piping shall minimise obstruction and maneuverability.
Any installation or assemblies of pipe support that is attached to the prefabricated tank is not allowed.
8.5.1.2 Inlet and Outlet Pipes All inlet and outlet pipes of the units of prefabricated biological treatment system must be pre-fitted at the factory. On-site drilling for holes is strictly prohibited. All jointing and pipe holes connection shall be factory fabricated/moulded. 8.5.1.3 Aeration Pipes a)
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The air distribution pipe used shall be rigid and can withstand temperatures up to 150 ºC and pressures of 25% more than the design pressure of the blower.
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b)
The air pipe from the blower to the process unit shall be above ground.
8.5.1.4 Sludge Transfer Pipes a) b)
No thread union/coupling is allowed at the sludge transfer pump piping. The connection shall be double flange with Grade 304 stainless steel bolt and nut. No bending is allowed for the sewage distribution pipe. A chamber shall be provided for any changing direction of the flow.
8.5.1.5 Effluent Pipes The effluent discharge piping system that passes through/bypasses the disinfection treatment facility shall be designed so as not to cause any nuisance. 8.5.2
Pumping System The pumps installed in the package system shall meet the requirements as stated in Table 8.3 below: Table 8.3 Technical Requirements of Pumping System
Name of Pump
Transfer Pump
Sludge Transfer Pump
RAS/WAS Pump
Application Area
Balancing Tank
Sludge Holding Tank
Clarifier
Minimum Throughlet
50 mm
50 mm
50 mm
Control
Automatic control Manual control by float switch by timer
Number of Pump
1 duty, 1 standby
1 duty for each tank
Type of Pump
Mechanical Submersible Pump
Mechanical Submersible Pump or Self Priming Pump
Necessities
Mandatory
Accessories
All pumps shall be completely installed with duct foot, guide rail and lifting chain made of Grade 304 stainless steel.
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Note:
1)
Non-submersible pumps shall be provided with parking bay with shade.
2)
The duct foot shall be installed and assembled at the factory. No installation/assemblies at site are allowed except for the connection of the transfer pipe and the guide rail. All fasteners of the duct foot shall be watertight.
8.5.3
Diffuser a) b) c)
8.5.4
The diffuser shall not be bolted to the bottom of the tank. The diffuser shall be removable and easy to re-install.
Flow Distribution Chamber a) b)
8.5.5
All diffusers must be supported from the tank base. A typical drawing of the diffuser support is shown in Figure 8.1.
Distribution box shall be provided with adjustable features. A typical drawing of the distribution box is shown in Figure 8.2. The design and construction of the distribution chamber shall prevent any sedimentation.
Manhole Cover/Inspection Chamber Cover The manhole cover shall follow the requirements as in Table 8.4: Table 8.4 Technical Requirements of Manhole Cover Description
FRP
HDPE
Ductile/Cast Iron
Size
600 mm x 600 mm or 600 mm diameter
Installation
At any location on top of the tank except at assembly joints, rib or reinforced ring location.
Load Bearing Capacity
≥ 3.5 kN/m2 (BS EN 12255-1:2002(E))
Maximum Deflection Limit
10 mm or the span divided by 200, whichever is smaller (BS EN 12255-1:2002(E))
Class
B 125 in accordance to BS EN 124:1994 or equivalent
Personnel Load
125 kN (fully walk-able) (BS EN 124:1994)
Design Safety Factor
4:1 for allowable stresses shall be met for all load combinations (ANSI/ASCE 7-98)
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Table 8.4 Technical Requirements of Manhole Cover (Continued) Description
FRP
HDPE
Ductile/Cast Iron
Temperature Range
27°C – 35°C (to incorporate thermal expansion and contraction)
Standard colour
Black
Coating
Aliphatic acrylic polyurethane non-skid coating
Resin
UV Protection
Note:
1. 2. 3. 4.
8.5.6
Black NA
Black - Epoxy coating of 200 µm
- Hot dip galvanised of 200 µm
Corrosion resistant general purpose polyester
NA
NA
Ultraviolet-light inhibitors shall be added to the laminate
Carbon black
NA
The collar of the manhole shall be raised with a minimum height of 100 mm above ground level. The cover shall be equipped with a frame support and hinge, and attached to the manhole opening. Each manhole cover must be properly labeled / marked for ease of identification of the unit process of the system. NA – not applicable
Anchor System Loading The tank anchor system (straps, cables, turnbuckles, etc.) shall have strength of at least 1.5 times the maximum uplift force of an empty tank without backfill in place. All wire straps, cables and turnbuckles must be made of Grade 304 stainless steel.
8.5.7
Landscaping The landscaping of the sewage package system shall be in accordance with those recommended in Section 6 of this Guidelines.
8.5.8
Odour Treatment The odour treatment shall be incorporated into the package sewage treatment plant and shall follow the requirements stipulated in Section 7.4.
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8.5.9
8.6
Ancillary Facilities The requirement and criteria of other ancillaries such as lifting facilities, road, water tank, stand pipe, etc shall be in accordance with the design criteria as stipulated in Section 6 and special requirements in Section 7.4.
Marking and Labelling Each tank shall at a minimum be marked with the following information: •
Manufacture’s name or trademark
•
Manufacturing serial number
• • •
Manufacturing date (MM/YY) Diameter and Capacity
Citation of the standard
The markings shall be printed and adhered to the tank.
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Appendix A Tables
Appendix A - Tables
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Appendix A
Appendix A Tables Table A1
Contaminants of Concern in Sewage Treatment
Table A3
Major Biological Treatment Processes Used for Sewage Treatment
Table A2
Typical Composition of Untreated Domestic Sewage
Table A4
Interim National River Water Quality Standards for Malaysia
Table A6
The Occupational Safety and Health Act 514, 1994 – Brief Summary of Contents
Table A5
Table A7 Table A8
River Clarification
Permissible limits for potentially toxic elements in soil Options for disposal of Sludge and reuse of biosolids
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Appendix A - Tables
Table A1 Contaminants of Concern in Sewage Treatment
Contaminants
Reason for Concern
Suspended solids
Suspended solids can lead to the development of sludge deposits and anaerobic conditions when untreated sewage is discharged in the aquatic environment.
Biodegradable organics
Composed principally of proteins, carbohydrates and fats, biodegradable organics are measured most commonly in terms of BOD (biochemical oxygen demand). If discharged untreated to the environment, their biological stabilisation can lead to the depletion of natural oxygen resources and to the development of septic conditions.
Pathogens
Communicable diseases can be transmitted by the pathogenic organisms in sewage.
Nutrients
Both nitrogen and phosphorus, along with carbon, are essential nutrients for growth. When discharged to the aquatic environment, these nutrients can lead to the growth of undesirable aquatic life. When discharged in excessive amounts on land, they can also lead to the pollution of groundwater.
Refractory organics
These organics tend to resist conventional methods of sewage treatment. Typical examples include surfactants, phenols and agricultural pesticides.
Heavy metals
Heavy metals are usually added to sewage from commercial and industrial activities and may have to be removed if the sewage is to be reused.
Dissolved inorganic solids
Inorganic constituents such as calcium, sodium and sulphate are added to the original domestic water supply as a result of water use and may have to be removed if the sewage is to be reused.
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Appendix A - Tables
Table A2 Typical Composition of Untreated Domestic Sewage Concentration (mg/l)
Constituent
Strong
Solids, total
Medium
Weak
1200
720
350
850
500
250
Fixed
525
300
145
Volatile
325
200
105
350
220
100
75
55
20
275
165
80
Settleable solids, ml/l
20*
10*
5*
Biochemical oxygen demand, 5 day, 20°C (BOD5, 20°C)
400
250
110
Total organic carbon (TOC)
290
160
80
1000
500
250
Nitrogen (total as N)
85
40
20
Organic
35
15
8
Free ammonia
50
25
12
Nitrites
0
0
0
Nitrates
0
0
0
15
8
4
5
3
1
Inorganic
10
5
3
Chlorides
100
50
30
Alkalinity (as CaCO3)
200
100
50
Grease
150
100
50
Dissolved, total
Suspended, total Fixed Volatile
Chemical oxygen demand (COD)
Phosphorus (total as P) Organic
* All values except settleable solids are expressed in mg/l.
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Appendix A - Tables
Table A3
Major Biological Treatment Processes Used for Sewage Treatment
Type
Common Name
Use
Aerobic processes Suspended growth
Carbonaceous BOD removal (nitrification)
Activated-sludge process Conventional (plug flow)
Carbonaceous BOD removal (nitrification)
Continuous-flow stirred-tank
Carbonaceous BOD removal (nitrification)
Step aeration
Carbonaceous BOD removal (nitrification)
Pure oxygen
Carbonaceous BOD removal (nitrification)
Modified aeration
Carbonaceous BOD removal (nitrification)
Contract stabilisation
Carbonaceous BOD removal (nitrification)
Extended aeration
Carbonaceous BOD removal (nitrification)
Oxidation ditch
Carbonaceous BOD removal (nitrification)
Sequencing batch reactor
Carbonaceous BOD removal (nitrification)
Suspended-growth nitrification
Nitrification
Aerated lagoons
Carbonaceous BOD removal (nitrification)
Aerobic digestion
Carbonaceous BOD removal (nitrification)
Conventional air
Stabilisation, carbonaceous BOD removal
Pure oxygen
Stabilisation, carbonaceous BOD removal Carbonaceous BOD removal
High-rate aerobic algal pond Attached growth
Combined processes
Trickling filters Low-rate
Carbonaceous BOD removal (nitrification)
High-rate
Carbonaceous BOD removal (nitrification)
Roughing filters
Carbonaceous BOD removal
Rotating biological contactors
Carbonaceous BOD removal (nitrification)
Packed-bed reactors
Carbonaceous BOD removal (nitrification)
Trickling filter, activated sludge
Carbonaceous BOD removal (nitrification)
Activated sludge, trickling filter
Carbonaceous BOD removal (nitrification)
Anoxic processes Suspended growth
Suspended-growth denitrification
Denitrification
Attached growth
Fixed-film denitrification
Denitrification
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Table A3
(continued)
Type
Common Name
Use
Anaerobic processes Suspended growth
Attached growth
Stabilisation, carbonaceous BOD removal
Anaerobic digestion
Standard-rate, single-stage Stabilisation, carbonaceous BOD removal High-rate, single-stage
Stabilisation, carbonaceous BOD removal
Two-stage
Stabilisation, carbonaceous BOD removal
Anaerobic contact process
Carbonaceous BOD removal
Anaerobic filter
Carbonaceous BOD removal, stabilisation (denitrification)
Anaerobic lagoons (ponds)
Carbonaceous BOD removal (stabilisation)
Aerobic/anoxic or anaerobic process Suspended growth
Single-stage nitrificationdenitrification
Carbonaceous BOD removal, nitrification, denitrification
Nitrification-denitrification
Nitrification, denitrification
Attached growth
Facultative lagoons (ponds)
Carbonaceous BOD removal
Combined processes
Maturation or tertiary ponds
Carbonaceous BOD removal
Anaerobic-facultative lagoons
Carbonaceous BOD removal
Anaerobic-facultative-aerobic lagoons
Carbonaceous BOD removal
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Appendix A - Tables
Table A4
Interim National River Water Quality Standards for Malaysia Classes*
Parameters (units)
II
IIA
IIB
III
IV
V
Ammoniacal Nitrogen (mg/l)
0.1
0.3
0.3
0.9
2.7
>2.7
BOD5 (mg/l)
1
3
3
6
12
>12
COD (mg/l)
10
25
25
50
100
>100
DO (mg/l)
7
5-7
5-7
3-5
<3
<1
PH
6.5-8.5
6-9
6-9
5-9
5-9
-
Colour (TCU)
15
150
150
-
-
-
Elect. Cond.# (mmhos/cm)
1000
1000
-
-
6000
-
Floatables
N
N
N
-
-
-
Odour
N
N
N
-
-
Salinity# (0/00)
0.5
1
-
-
2
Taste
N
N
N
-
-
Total Diss. Solid# (mg/l)
500
1000
-
-
4000
Total SS (mg/l)
25
50
50
150
300
>300
Temperature (0C)
-
Normal ±2
-
Normal ±2
-
-
Turbidity (NTU)
5
50
50
-
-
-
F. Colif. †(counts/100 ml)
10
100
400
5000
5000
-
5000
5000
(20 000)‡
(20 000)‡
> 50 000
50 000
50 000
Tot. Colif. (counts/100 100 ml) N
No visible floatable materials/debris, or no objectionable odour, or no objectionable taste
*
Classes are described on the following table
#
Related parameters, only one recommended for use
†
Geometric mean
‡
Maximum not to be exceeded
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Table A5
River Clarification
Class
Uses
I
♦ Conservation of natural environment ♦ Water supply I - practically no treatment necessary (except by disinfection or boiling only) ♦ Fishery I - very sensitive aquatic species
IIA
♦ Water supply II - conventional treatment required ♦ Fishery II - sensitive aquatic species
IIB
Recreational use with body contact
III
♦ Water supply III - extensive treatment required ♦ Fishery II - common, of economic value, and tolerant species ♦ Livestock drinking
IV
Irrigation
V
None of the above
Note: This data is adapted from the Water Quality Criteria and Standards for Malaysia, Final Report July 1986, Department of Environment.
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Appendix A - Tables
Table A6
The Occupational Safety and Health Act 514, 1994 - Brief Summary of Contents
Part No.
Content
I
Preliminary
II
Appointment of Offices
III
National Council for Occupational Safety and Health
IV
General Duties of Employers and Self Employed Persons
V
General Duties of Designers, Manufacturers and Suppliers
VI
General Duties of Employees
VII
Safety and Health Organisations
VIII
Notification of Accidents, Dangerous Occurrence, Occupational Poisoning and Occupational Diseases and Inquiry
IX
Prohibition Against use of Plant or Substance
X
Industry Codes of Practice
XI
Enforcement and Investigation
XII
Liability for Offences
XIII
Appeals
XIV
Regulations
XV
Miscellaneous
The Occupational Safety and Health Act (OSHA) was enacted by the Parliament in 1994. In general, it is an enabling law in that the duties, responsibilities, penalties and guidelines are to be followed by each specific industry. The following table provides an outline of OSHA. Parts of OSHA have a specific target audience. For example, if the professional is a designer, then Part V would be applicable with respect to Occupational, Safety and Health in their design.
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Table A7
Permissible limits for potentially toxic elements in soil Parameters
Limits (mg/kg)
Zinc
900
Copper
250
Nickel
150
Cadmium
12
Lead
1000
Mercury
4
Chromium
1000
Arsenic
150
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Table A8
No
Options for disposal of Sludge and reuse of bio-solids Type of sludge/ by-product
1
Liquid primary sludge and septage
2
Dewatered primary sludge and dewatered septage
3
Pond sludge
4
Dewatered pond sludge
5
Digested sludge
6
Dewatered digested sludge
7
Lime stabilised sludge
9
Thermally dried sludge (pellets/granules)
8
10
Compost product
Incinerator ash
Source/ Treatment Process
Option for Disposal or Utilization
- Imhoff tanks - Primary and secondary clarifiers - Septic Tanks
D
- Oxidation ponds - Aerated lagoons - Waste stabilization ponds
D, F, R
- Digesters - Sludge lagoons - Anaerobic ponds
D, F, R
- Lime stabilisation
C, D, F, R, S
- Thermal drying
A, C, D, F, L, R, S, SP
- Drying beds - Mechanical dewatering equipment
C, D, I, S
- Drying beds - Mechanical dewatering
C, D, F, I, R, S
- Drying beds - Mechanical dewatering
C, D, F, I, R, S
- Composting
A, C, D, F, L, R, S
- Incineration
C, D, S, SP
NOTES: A = Use in agriculture C = Disposal to controlled dumpsites D = Disposal to dedicated sludge disposal sites F = Use in forestry/non-food crops I = Incinerate L = Use for landscaping at public amenity areas S = Disposal to sanitary landfill sites R = Use in rehabilitation of degraded SP = Recycled into special product, e.g. building material 224
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Appendix B References
Appendix B - References
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Appendix B - References
Malaysian Standards ♦ MS 29 Specification for aggregates from natural sources for concrete ♦ MS 144 Specification for cold reduced mild steel wire for reinforcement of concrete ♦ MS 145 Specification for steel fabric for the reinforcement of concrete ♦ MS 146 Specification for hot rolled steel bars for reinforcement of concrete ♦ MS 416 Code of practice for the use of structural steel in building ♦ MS 523 Specification for concrete including ready mixed concrete Part 1 Guide to specifying concrete Part 2 Methods for specifying concrete mixes Part 3 Procedures to be used in producing and transporting concrete Part 4 Procedures to be used in sampling, testing and assessing compliance of concrete ♦ MS 739 Specification for hot-dip galvanised coatings on threaded fasteners ♦ MS 740 Specification for hot-dip galvanised coatings on iron and steel articles ♦ MS 822 Specification for sawn-timber foundation piles ♦ MS 1037 Specification for sulphate resisting portland cement ♦ MS 1195 Code of practice for structural use of concrete Part 1 Design and construction Part 2 Part 3
Special circumstances Design charts for singly reinforced, doubly reinforced beams and rectangular columns ♦ MS 1227 Specification for portland pulverised fuel ash cement ♦
MS 1228: 1991
Code of Practice for Design and Installation of Sewerage Systems
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Appendix B - References
♦
MS 1241
Specification for fibreglass water tanks - effective capacity of less than 2000 litres ♦
MS 1292
Specification for rubber seals – water stops for sealing joints in concrete ♦
MS 1387
Specification for ground granulated blast furnace slag for use with portland cement ♦
MS 1390
Specification for glass-reinforced polyester panels and panel water tanks British Standards ♦
BS 476
Fire tests on building materials and structures ♦
BS 1161
Specification for aluminium alloy sections for structural purposes ♦
BS 1615
Specifications for anodic oxidation coatings on aluminium. ♦
BS 3396
Woven glass fibre fabrics for plastics reinforcement ♦
BS 3532
Method of specifying unsaturated polyester resin systems ♦
BS 3749
Specification for E glass fibre woven roving fabrics for the reinforcement of polyester and epoxy resin systems ♦
BS 4248
Specification for supersulfated cement ♦
BS 4848
Hot rolled structural steel sections
Part 2 Specification for hot finished hollow sections ♦ BS 4921 Specification for sherardized coatings on iron and steel ♦
BS 5493
Code of practice for protective coating of iron and steel structures against corrosion
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Appendix B - References
BS 7079
♦
Preparation of steel substrates before application of paints and related products BS 7123
♦
Specification for metal arc welding of steel and concrete BS 8118
♦
reinforcement
Structural use of aluminium Part 1 Part 2
Code of practice for design Specification for materials, workmanship and protection
European Standard EN 10088
♦
Stainless Steel Part 1 Part 3
List of Stainless Steels Technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright products of corrosion resisting steels for general purposes
EN 10029
♦
Specification for tolerances on dimensions, shape and mass for hot rolled steel plates 3 mm thick or above EN ISO 9445
♦
Continuously cold-rolled stainless steel narrow strip, wide strip, plate/sheet and cut lengths. Tolerances on dimensions and form EN 754
♦
Aluminium and aluminium alloys. Cold drawn rod/bar and tube. Part Part Part Part
1 2 7 8
♦
Technical conditions for inspection and delivery Mechanical properties Seamless tubes, tolerances on dimensions and form Porthole tubes, tolerances on dimensions and form
EN 755
Aluminium and aluminium alloys. Extruded rod/bar, tube and profiles. Part Part Part Part Part Part Part Part
1 2 3 4 5 6 7 8
Technical conditions for inspection and delivery Mechanical properties Round bars, tolerances on dimensions and form Square bars, tolerances on dimensions and form Rectangular bars, tolerances on dimensions and form Hexagonal bars, tolerances on dimensions and form Seamless tubes, tolerances on dimensions and form Porthole tubes, tolerances on dimensions and form
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Appendix B - References
Part 9 ♦
Profile, tolerances on dimensions and form
EN 1676
Specifications for aluminium and aluminium alloy. Alloyed ingots for remelting. ♦
EN 12373
Specification for aluminium and aluminium alloys. Anodizing. Part 1 ♦
Method for specifying decorative and protective anodic oxidation coatings on aluminium and its alloys.
EN 10162
Specification for cold rolled steel sections. Technical delivery conditions. Dimensional and cross-sectional tolerances. ♦
EN 13923
Filament-wound FRP pressure vessels. Materials, design, manufacturing and testing. ♦
EN ISO 8503
Preparation of steel substrates before applications of paints and related products. Surface roughness characteristics of blast-cleaned steel substrates. Part 1 ♦
Specifications and definitions for ISO surface profile comparators for the assessment of abrasive blast-cleaned surfaces.
EN 10025
Hot rolled products of structural steels. Part 1 Part 3 Part 4 ♦
General technical delivery conditions. Technical delivery conditions for normalized/normalized rolled weldable fine grain structural steels. Technical delivery conditions for thermomechanical rolled weldable fine grain structural steels
EN ISO 2063
Thermal spraying. Metallic and other inorganic coatings. Zinc, aluminium and their alloys. ♦
EN 14020
Reinforcements. Specification for textile glass roving. Part 1
Designation
Part 3
Specific requirements
Part 2 ♦
Methods of test and general requirements EN 10210
Specification for hot finished structural hollow sections of non-alloy and fine grain steels
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Part 2
Tolerances, dimensions and sectional properties. EN 10296
♦
Welded circular steel tube for mechanical and general engineering purposes. Technical delivery conditions. Part 1 Part 2
Non-alloy and alloy steel tubes. Stainless steel
EN 10297
♦
Seamless circular steel tubes for mechanical and general engineering purposes. Technical delivery conditions. Part 1
Non-alloy and alloy steel tubes.
EN 10305
♦
Steel tubes for precision applications. Technical delivery conditions. Part Part Part Part
1 2 3 4
Part 5 Part 6 ♦
Seamless cold drawn tubes Welded cold drawn tubes Welded cold sized tubes Seamless cold drawn tubes for hydraulic and pneumatic power systems Welded and cold sized square and rectangular Welded cold drawn tubes for hydraulic and pneumatic power systems EN 14118
Reinforcements. Specification for textile glass mats. (chopped strand and continuous filament mats). Part 1 Part 2 Part 3 ♦
Designation Methods of tests and general requirements Specific requirements EN 10083
Specification for steels for quenching and tempering Part 3
Technical delivery conditions for alloy steels
ASTM Standard ♦
ASTM D4097
Standard specification for contact-moulded glass-fibre-reinforced thermo set resin corrosion-resistant tanks.
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Appendix B - References
♦
ASTM E84
Standard test method for surface burning characteristics of building materials. ♦
ASTM C582
Standard specification for contact-moulded reinforced thermosetting Plastic (RTP) laminates for corrosion-resistant equipment. AS Standard ♦
AS 3750.2
Paints for steel structures – Ultra high-build paint ♦
AS/NZS 3750.12
Paints for steel structures – Alkyd/micaceous iron oxide ♦
AS/NZS 2312
Guide to the protection of structural steel against atmospheric corrosion by the use of protective coatings. Other Reference Materials ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦
232
Buffer Guidelines for the Siting and Zoning of Industries, Department of Environment Environmental Quality Act 1974
Environmental Quality (Sewage and Industrial Effluents) Regulations, 1979 Occupational Safety and Health Act, 1994 (OSHA)
Water Quality Criteria and Standards for Malaysia, Final Report, July 1986, Department of Environment
Environmental Impact Assessment Guidelines for Municipal Solid Waste, Sewage Treatment and Disposal Projects, Department of Environment. Factories and Machinery Act 1967 (Revised – 1974) Uniform Building By-Law (UBBL), 1984 Town and Country Planning Act, 1976 Sewerage Services Act 1993
Water Services Industry Act 2006 Electrical Act
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Appendix B - References
Other Guidelines in This Set The Malaysian Sewerage Industry Guidelines is comprised of 5 volumes: ♦ ♦ ♦ ♦
Volume 1
Sewerage Policy for New Developments
Volume 3
Sewer Networks and Pump Stations
Volume 2 Volume 5
Sewage Treatment Plants
Sewerage Works Procedures Septic Tanks
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Appendix C Supervisory Control and Data Acquisition System (SCADA)
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
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Appendix C - Supervisory Control and Data Acquisition System (SCADA)
C-1
Introduction: Overview
SCADA is the acronym for Supervisory Control And Data Acquisition, SCADA or Human-Machine Interface (HMI). The system allows distributed input to be continuously monitored without the intervention of an operator and allows supervisor or operator (depending on security level) to remotely control of equipment operating status. Data acquisition begins at the Programming Logic Controller, PLC level and includes meter readings and equipment statuses that are communicated to the SCADA as required. Data is then compiled and formatted in such a way that a control room operator using the HMI can make appropriate supervisory decisions that may be required to over-ride normal PLC controls. (A SCADA system includes all the pieces, HMI, controllers, I/O devices, networks, software, etc.). SCADA systems typically implement a distributed database which contains data elements called tag points. A tag point represents a single input or output value monitored or controlled by the system. Tag points can be either “hard” or “soft”. A hard point is representative of an actual input or output connected to the system, while a soft point represents the result of logic and math operations applied to other hard and soft points. The point values are normally stored as value-timestamp combinations; the value and the timestamp when the value was recorded or calculated. A series of value-timestamp combinations is the history of that point. The SCADA provides a user-friendly front-end to a control system containing programmable logic controller (PLC) that provide automated, pre-programmed control over a process. This enables the SCADA system to gather data automatically and remotely rather than manually and site in-situ. A SCADA software can be linked to a database (normally SQL-Structured Query Language), to provide instant trending, diagnostic data, scheduled maintenance procedures, logistic information, detailed schematics for a particular sensor or machine, and expert-system troubleshooting guides. Most major PLC manufacturers have offered integrated HMI/SCADA systems, many of them using open and nonproprietary communications protocols (such as MODBUS or Profibus). In short, interfacing on of SCADA with PLC offers efficient monitoring and control of process in a large installation site and with large number of distributed equipment at a site. SCADA provide alarm notification, historical and on-line trending plots of control parameters for effective process monitoring and control. SCADA system can also be implemented with PPM schedule maintenance notification and reminder. The SCADA that are installed at the remote sites can be linked to a Master Station via communication system (Radio frequency or WIFI or other on-line communication channels). The data from an equipment is collected via on-line data acquisition or, unless otherwise allowed, on batch mode via data logging devices.
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Appendix C - Supervisory Control and Data Acquisition System (SCADA)
The SCADA software can also activate alarm messaging to inform the operator station for exceptional event (critical alarm) reporting. Remote Access Server (RAS) features can provide for either via Internet or other dial-up method (fixed line and/ or wireless modem). All the proposed SCADA software shall be scalable and flexible enough to allow the integration of any additional SCADA controller in future expansion. It shall provide with many industrial standard protocols to allow the user to integrate easily.
C-2
Purpose
This document will provide basic technical requirement for implementation of integrated SCADA/HMI in sewerage system.
C-3
General Requirements
The SCADA system shall be scalable process control solutions designed to meet the required automation needs in the sewerage industries. The system shall provide the required level of performance, flexibility, ease of use, and low life-cycle cost of ownership, making use of the following technology that includes: The SCADA system shall be Window based client/server system and make use of the following technologies: • • • •
C-4
Dynamic data caching, alarming, human machine interface, history collection, and reporting functions; Web viewable, providing secure, advanced user interface HMI capabilities based on an open industry standard html file format and Web Browser access; Extensive list of communication interfaces; Secure Internet Browser based on-line documentation and support.
Architecture
The SCADA architecture shall be flexible and scalable to allow expansion requirements. The basic architecture shall incorporate all but not limited to the followings: • • • • •
238
Standard based workstations; powerful Windows based server(s); Windows based clients; Industry communication standards shall follow IEEE specification; object-based configuration tools;
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• • • • • •
C-5
controllers/remote terminal units; with power surge protection; Modem: digital or analog; Network switches or routers; Uninterrupted Power Supply (UPS); data logger & storage devices for continuous monitoring of operation in the event of cessation of communication;
SCADA Requirement
The SCADA shall utilize all but not limited to the followings available technologies and features: • •
• • • •
HMI Web – A web-based architecture that allows HMI and application data which uses HTML display format to provide casual access of process graphic displays. Real-time Database – a true Client/Server architecture where a real-time database on the server provides data to a number of client applications including: o Operator stations o Microsoft office applications (such as Microsoft Excel or Microsoft Access) o Internet explorer Open Systems – incorporates open technologies and standards including SQL, ODBC, DDE, Visual Basic, and other OLE for process control. Infrastructure – in cooperate alarm/event management system; configure reports, history collection and a variety of standard system trends. On-line documentation – provides users access to system information and documentation. Interfaces – Data acquisition ability from a wide variety of remote terminal units and controllers.
Other powerful supervisory control features include: • • • • • • • • •
Integrated detail displays, custom graphics, alarms, history, and reports Standard control functions Operator security Redundant Windows XP/server operation A common interface for SCADA and other control types such as Hybrid Control Database and diagnostic integration with process and discrete controllers Graphical building tools Standard and user-definable application templates International system and local language support
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•
Optional applications such as Alarm Pager interface, Downtime Analysis, and statistical Process Quality Control
Standard facilities shall include but not limited to the followings: •
Windows based HMI
Multiple local and remote operator stations Interface: TCP/IP, fieldbus, Modbus, Hart •
Support for redundant controller/RTU communications
Integration of multiple systems Real-time data access for a wide variety of process connected devices • Supervisory data acquisition and control of controllers and remote terminal units • alarm management • Extensive historian and trending • Flexible standard or customized reports • Optional Live Video Capture integration • Industry standard local and wide area network integration • Secure data integration with third party applications • ActiveX Document and Scripting support
C-6
Operator Interface
The operator interface station shall allow object based graphics to provide the HMI for the user with object concern. The system shall employ industry de-factor standards, such as Microsoft Windows, HTML and the Internet so as to minimize operator training due to familiarity of operating environment. Critical information is conveyed using dedicated enunciators for alarms, controller communication failures, operator/controller messages and equipment downtime conditions. A dedicated alarm line shows the most recent (or oldest) highest priority, unacknowledged alarm at all times. Software system displays shall include but not limited to the followings: • Menu/navigation displays • Alarm summary • Event summary • Trends • Operating groups • System status displays • Configuration displays • Loop Tuning displays • Diagnostic and maintenance displays • Summary displays
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Optional Live Video integration shall provide remote viewing and viewing control features. Security software feature shall provide restricted access, no access and full access (plant management). Network access shall permit authorized operator stations on a network to share a preconfigured number of connections to the system. This allows a number of users on a network to access production data on off-line basis.
C-7
Database
The SCADA software shall but not limited to the following real-time database: • Analog configuration parameters • Digital configuration parameters • Accumulator configuration parameters • User defined configuration parameters Each point in the database has a number of associated configurable parameters, all of which can be referenced relative to a single ‘tag name’. SCADA shall maintain the real time database that requires frequent high-speed access as memory resident information and other less frequently accessed data as disk resident data. Memory resident data is logged to data storage device every specified time frame defined by the administrator to minimize the loss of data in the event of loss of power.
C-8
Alarm/Event Management
The SCADA software System shall provide comprehensive alarm and event detection, management, and reporting facilities. Alarm presentation of alarm / event management shall include but not limited to the followings: • • • • • • • •
Multiple alarm priorities Dedicated alarm zone Configurable alarm priority colors Associated display Audible alarms Alarm cutout Area assignment Operator log
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• • • •
Hierarchical alarming Alarm/event reporting Alarm/communication/ message/downtime annunciator Alarm priority escalation
The standard Alarm Summary display shall allow operators to focus on the problem at hand by supporting filters. Alarms may be filtered by: • • •
Area or location or unit processes Acknowledge Status Priority
Colors for the various priority levels of alarms can be configured by the user for display purposes in the Alarm Summary and on custom graphics. The recommended color codes are provided in Appendix 1. The software shall support configuration of alarm priority colors and display on all process graphic displays to enables operators immediately determine critically of the alarm. The alarm shall annunciate in the status zone blinks with the color of the highest priority for unacknowledged alarm. The alarms configuration shall consist but not limited to the followings: • • • • • •
SPV Hi SPV Lo Transmitter Hi Transmitter Lo Trip Time out
With each of the configured alarms assigns a priority ranging from "Attention" acknowledge of non-critical alarm that required maintenance attention, "Responsive" - action required with predefined period, "Urgent" - action required immediately. The Alarm/Event summary shall list but not limited to the followings: • Alarms
• Alarm Acknowledgments • Return to normal
• Operator Control Actions
• Operator Login & Security Level Changes • On-line Database Modifications • Communications Alarms
• System Restart Messages 242
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C-9
Historian
Historical trend shall provide wide range of sampling frequencies in both datapoint and average formats. The history trend intervals are shall be able to but not limited to the following displays: • second data-point of pre-defined scale • minute data-point of pre-defined scale • hour data-point of pre-defined scale • minute-average of pre-defined scale • hour-average of pre-defined scale • day-average of pre-defined scale • Month-average of pre-defined scale The historical data is to be display in various formats describe herewith: • Graphical trend plot displays (average, max, min, and other statically format) • Tabulation displays (average, max, min, and other statically format) • Query databases of selected parameters.
C-10 Graphical Trending Graphical trending configuration shall be able to configure by selecting the parameters to be plot and its time-scales. Minimum trend types shall include but not limited to the followings: • Single and Multi bar graphs (selectable scales) • Single and Multi-line trends plot (selectable scales) • Multi-range trends plot (selectable scales) • X-Y line and scatter trend plots (selectable scales) •
Mathematical plots (logarithm scale, moving average, etc)
Functions provided for analyzing and manipulating data include: • Combination real-time/historical plots • zooming, panning, and scrolling • Configurable trend density • Saving of trend plot and expert to various format (*.xls, HTML, XLM, etc) • clipboard copy/paste enable
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C-11 Report Format The software shall provide but not limited to the following report formats: • • • •
Alarm/Event Log reports - selectable time frame, filterable events and alarms to enable traceability of alarm. Exportable Excel / Access format - able to save selected data/report format to Microsoft Excel/Access format. Statistical data analysis format - generates reports of selectable statistical functions such as Max/Min and standard deviation. Point Attribute Log - displaying specific attributes selectable from a list.
Reports should be generated as required time frame (interval), event-driven, or ondemand basis. Report may be directed to screen, printer, file, or directly to another computer for analysis or viewing electronically.
C-12 Security The SCADA software shall provide configurable security levels, control levels and area assignments. These may be configured for each individual operator or alternatively for each operator station. The security levels shall be able to configure the following security levels: Level Level Level Level
1: 2: 3: 4:
Sign-on for View mode only View only mode with alarm acknowledge Level 2 plus control of field parameters Level 3 plus field parameters of level 4, configure standard system infrastructure such as reports Level 5: Level 4 plus user configured field parameters Level 6: Unlimited access Operator sign-on/sign-off shall be logged. Any actions initiated by an operator are logged in the Event database with the operator identifier. In addition any control actions to a given point is only allowed if the control level configured in the operator profile exceeds the level assigned to the point. Logon password shall not be less than 6 alphanumeric characters and shall be encrypted. Operators may change own passwords; however, new password shall not be the same as the last 10 passwords used in the previous 3 months. Three unsuccessful attempts of logon shall lock the operator out for a lock-out period. Once logged on, an operator can log off at any time or will be automatically signed off after a defined period of inactivity.
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Area assignments limit operator access to graphics, alarms and point data to assigned areas, providing effective plant partitioning. Individual operator profiles, including security levels, control levels and area assignments, are activated when operators sign on to the system. In addition, area profiles can be created enabling plant areas to be enabled or disabled for control, between certain time and date criteria.
C-13 Scripting The software shall have the VB or VBA scripting language enable to allow user to create script that will run when a display is active or scripts can also be attached to server objects like point parameters, alarm events, report completion and other events.
C-14 Interfaces SCADA software provides Data Acquisition and Control facilities to communicate with a wide range of controllers and Remote Terminal Units (RTUs). The controllers connection type shall comply with the following communication protocol: Serial / TCP/IP / ControlNet / Modbus+ / ASCII / TCP/IP / Ethernet Data Acquisition –supports acquisition of data using either: Periodic Scanning
C-15 Distributed Server Architecture Distributed Server Architecture is integrated processes when there are multiple control stations, or for segmenting control across units, providing the ultimate flexibility for both operations and control. Distributed Server Architecture also provides the maximum flexibility for geographically distributed sites.
C-16 Web Server SCADA software shall provide Web Server capability to provide integration mechanism for plant-centric operational information. Based on the SCADA software Distributed Server Architecture, a web server bridges the Process Control and Enterprise domains, dynamically tracking the “pulse” of the enterprise. Web server brings many benefits to the end user: • •
Isolation of non-critical enterprise functions from the process control system Consolidated business system integration to/from many SCADA software systems
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• • •
Consolidation of casual users’ accounts and licenses in one location Cross-system reporting Minimal engineering requirements
C-17 Digital Video Monitoring The software may have optional Digital Video Monitoring that integrates digital video controls and storage with the software to assist in process monitoring. Some of the features are: • • • • •
Remote monitoring of unmanned sites Integration with SCADA software, providing event-based capture and storage of video images Event-activated, user-activated, and scheduled recording Ability to search stored video, based on SCADA software events Scalability from 4 cameras to more than 1,000 cameras.
The DVM shall base on open system hardware that digitizes video from standard video cameras and transports the video to SCADA software clients anywhere on the network for real-time viewing.
C-18 Integrated Maintenance Management Integrated Maintenance Management (IMM) delivers computerized maintenance management system (CMMS) – completely integrated with SCADA software. IMM shall deliver but
not limited to the following key benefits: • • • •
More efficient preventive and predictive maintenance Reduced downtime of critical plant equipment Effective work scheduling Automated creation of work orders from SCADA software events and data values
IMM enables the automated creation, assignment, tracking and closing of maintenance work orders. If required, work orders can also be manually raised. This is all managed from either your IMM SQL server database with full access available through the open Web-based interface of IMM.
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C-19 Application Report The SCADA software shall have the capability to produce but not limited to the following reports: • • • • • •
Batch Report Downtime analysis Schedule maintenance Statistical Process & Quality Control (SPQC) Event archiving Alarm messaging (SMS or pager)
Batch Reporting –integrated reporting of batches process data, to be compiled and archived by the SCADA software. The batch reports either as a CSV file or Microsoft Excel, if available. Downtime Analysis –to detect, record and code any equipment breakdowns or process delays to provide plant downtime analysis. A list of all current downtime events is maintained as well as the history of previous downtime events, with each assigned a category and a reason code. Downtime reports may be printed periodically or on-demand, showing downtime duration sorted by categories and reasons. Schedule Maintenance –allows supervisory control to schedule at a specified time. The maintenance report of the equipment is to be reported. Statistical Process & Quality Control (SPQC) - generates statistical report of average (of specified time period) of the real-time data collected by the system. Event Archiving –archiving events logged data by the system that based on sampling frequency and storage capacity. Alarm Messaging – reports the alarm messages sent designated supervisors. The report shall incorporate summary of alarm messages by alarm type and supervisors.
C-20 Application Programming Interface Application programming interface (API) shall be provided for interfacing with SCADA software server and the client network based. The API (programmed in C/C++(visual) or programmed in VB (Visual Basic)) on the server includes the following functions: • •
read and write to control module parameters in the database access to historical data
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• • • • •
initiate supervisory control actions access to the alarm/event subsystem access to user-defined database provide a prompt for operator input create alarms/events
C-21 User Documentation SCADA software documentation shall be made available in three basic forms: •
•
•
Electronic On-line Documentation using HTML Internet Browser
On-line Help (F1 function key from within applications) Printed documentation
C-22 Specifications and Sizing SCADA software Client/Server Specifications
Basic Server Workstation Specifications Processor Memory Hard Disk Size Display Resolution Operating System (Minimum) Network Protocols
Pentium Processor (Latest version) 1 GB 200 GB 1024 x 768, 65K colors Microsoft Windows (Latest edition) TCP/IP
Basic Client Workstation Specifications Processor Memory Hard Disk Size Display Resolution Operating System (Minimum) Network Protocols
248
Pentium Processor (Latest version) 1 GB 200 GB 1024 x 768, 65K colors Microsoft Windows NT (Latest edition) TCP/IP, NFS
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Appendix C - Supervisory Control and Data Acquisition System (SCADA)
SCADA software Server Performance
Operational Display Update Maximum Continuous Display Update Rate
1 sec
Typical Field Change to Display Update Time with 100 Parameters Per Display on a Single Station/ Server
< 2 sec
Typical Display Call Up Time with 100 Parameters on a Single Station/Server (call up time is dependent on display complexity; this excludes the first initial call up)
< 2 sec
SCADA Storage Sizing
Standard Sampling Rate
Default Duration
1 minutes
24 hours
1441
69 days
100 000
6 minute average
7 days
1682
416 days
100 000
1 hour average
7 days
170
11.4 years
100 000
8 hour average
3 months
281
91.2 years
100 000
24 hour average
1 year
368
273.8 years
100 000
Sewage Treatment Plants
Default Samples
Volume 4
Maximum Duration
Storage Capacity (maximum no. of samples)
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Appendix C - Supervisory Control and Data Acquisition System (SCADA)
Attachment C - 1: Status/Alarm Event State
250
Color Coding for Equipment Status
Color & Blinking Status
Notes of Event
Running
Green (Non-Blinking)
Equipment is in operating status
Standby
Red (Non-Blinking)
Equipment is in standby operating status
Off
Red (Blinking)
Equipment is “Off” or “Manual” mode.
Trip
Amber (Blinking):
Equipment “Tripped” due to the followings reasons: 1) ELR detection; 2) PSR detection; 3) Over-current; 4) Over-heated motor; 5) MCB Trip;
SP High Level
Yellow (Non-Blinking)
Alarm event of high level than set point
SP Low Level
Light Blue (NonBlinking)
Alarm event of lower level than set point
Transmitter Hi
Yellow (Blinking)
Alarm event due to transmitter high (<=4mA) value.
Transmitter Lo
Light Blue (Blinking)
Alarm event due to transmitter low (<=4mA) value.
Time Out
Amber (Blinking)
Alarm due to time out by PLC timer or other timer.
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Malaysian Sewerage Industry Guidelines
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
Instrumentation Panel - Local
Instrumentation Panel - Remote Instrumentation Panel - Battery Low TNB Power (kWh meter)
PLC System
PLC (battery Low)
DO
DI
AO
1
1
Indicator
1
1
Data Record
1
1
Indicator
1
1
Measure
Battery Charger Penstock
SCADA Control / Monitoring
Indicator Indicator
Analog (A)/ Digital (D) AI
Description of Control Point (For Each Equipment)
Description of Monitoring Point (For Each Equipment)
Instrumentation Panel
SCADA Control and Monitoring Function Requirement
Qty
Item
Attachment C - 2:
1
1
1
1
Alarm Low (Fault Report)
Alarm (Fault Report)
Penstock Panel: Manual Switch
Indicator
1
1
Penstock Position Actuator (%)
IP open close control
1
RTU via RS-485 Serial Link Alarm - High torque
Penstock - Fully Open
Indicator
1
1
Penstock Panel: Auto Switch
Penstock - Fully Close
Penstock - To Open / To Close
Penstock - UPS Low UPS (battery Low) Penstock Primary Coarse Screen
Indicator
Inlet
Indicator Remote Control Indicator
Measure
1
1
1
1
1
1
1
1
1
1
Screen - Trip
Indicator
1
1
Alarm (Fault Report)
Screen - Manual Mode
1
1
Screen - To Start / Stop
1
1
Screen - Run-hour record
Indicator Remote Control Reset of HourRun meter
0
Software counter running hours
Differential Level : Upstream
1
1
Differential Downstream
Control Start / Stop operation by diff. level
Screen - Run
Indicator
Screen - Auto Mode
Level
RSP Pumps Pump - Run Pump - Trip Pump - Off (MCCB)
Pump - To Start / Stop
Pump - Run-hour record
Pump - Ampere Pump - Voltage
Sewage Treatment Plants
Indicator
Indicator :
Indicator
Indicator Indicator Indicator Remote Start/ Stop Reset of HourRun meter Reading Reading
1
1
1
1
1
1
Counter - Number of start / stop
Ref level for upstream.
1 1 1
1 1 1
Record number of Start / stop Alarm (Fault Report) Record non-operation hours
1
1
Software control / PLC
0
Software counter running hours
1 1
1 1
Record when operation Record when operation
Volume 4
251
AO
DI
DO
1
1
RJ45 / RS485
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Cut-off operation Control Start / Stop operation by diff. level Control Start / Stop operation by diff. level Control Start / Stop operation by diff. level Control Start / Stop operation by diff. level For fault identification (Alarm Fault report) For fault identification (Alarm Fault report) For fault identification (Alarm Fault report) For fault identification (Alarm Fault report) For fault identification (Alarm Fault report)
1
Record number of Start / stop
1
Record non-operation hours
Pump - Soft Starter Amp/Volt Comm.
Parameters Setting / Review
Float level US Level
Float Level - L0 On/Off Float Level - L1 On/Off
Level measurement
Float Level - L2 On/Off
Indicator
Float Level - L3 On/Off
Indicator
Float Level - L4 On/Off
Indicator
Float Level - L0 Fault
Indicator
Float Level - L1 Fault
Indicator
Float Level - L2 Fault
Indicator
Float Level - L3 Fault
Indicator
Float Level - L4 Fault
Indicator
Sump Pump / Dewatering Pump Pump - Run
Indicator
1
Pump - Off (MCCB) Pump - To Start / Stop
1
Pump - Trip
Indicator Indicator
Indicator
Pump - Run-hour record
Ampere / Volmeters
Indicator Remote Start / Stop Reset of Hour-Run meter
Pump - Ampere
Reading
Float level
Pump - Voltage
1
1
Alarm (Fault Report)
1
1
Software control / PLC
0
Software counter running hours
1
1
Record when operation
1
1
Record when operation
1
1
Indicator
1
1
Screen - Run
Indicator
1
1
Record number of Start / stop
252
Screen - Trip
Screen - Auto Mode
Screen - Manual Mode
Screen - To Start / Stop
Indicator
1
Indicator Indicator
1
Remote Control
1 1
Volume 4
1 1 1
Indicator
1
Float Level - L0 Fault
1
Float Level - L1: ON / OFF
Indicator
1
Float Level - L1 Fault Secondary Fine Screen
Indicator
Cut-off operation Control Start / Stop operation by diff. level For fault identification
Float Level - L0: ON / OFF
Reading
SCADA Control / Monitoring
AI
Description of Control Point (For Each Equipment)
Description of Monitoring Point (For Each Equipment)
Analog (A)/ Digital (D)
Qty
Item
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
1
1
For fault identification Alarm (Fault Report)
Malaysian Sewerage Industry Guidelines
Screen c/v - Trip
Screen c/v - Run
Screen c/v - Auto Mode
Screen c/v - Manual Mode
Screen c/v - To Start / Stop
DO
DI
Mechanical Differential Level : Upstream Mechanical Differential Level : Downstream Screenings Conveyor
AO
Screen - Run-hour record
AI
Description of Control Point (For Each Equipment)
Description of Monitoring Point (For Each Equipment)
Analog (A)/ Digital (D)
Qty
Item
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
SCADA Control / Monitoring
0
Software counter running hours
Indicator
1
1
Indicator
1
1
Ref level for upstream.
Indicator
1
1
Record number of Start / stop
Reset of Hour-Run meter
Indicator
1
Indicator
1
Indicator
Remote Control
1 1
1 1 1
1
Control Start / Stop operation by diff. level
Alarm (Fault Report)
Screen c/v - Run-hour record
Reset of Hour-Run meter
0
Screenings Wash Water Pumps
Software counter / Interlock with screen operation with delay off.
Wash-water Pump - Trip
Indicator
1
1
Alarm (Fault Report)
Wash-water Pump - Run
Wash-water Pump - Auto Mode Wash-water Pump - Manual Mode Wash-water Pump - To Start / Stop
Indicator
1
Indicator
1
1 1
Indicator
1
1
Remote Control
1
1
Wash-water Pump - Run-hour record
Reset of Hour-Run meter
0
Grit Blower - Run
Indicator
Indicator
1
Software counter / Interlock with screen operation with delay off.
1
1
Alarm (Fault Report)
Grit / Grease System Grit Blower - Trip
Grit Blower - Auto Mode
Grit Blower - Manual Mode
Grit Blower - To Start / Stop
Indicator
1
Indicator
Remote Control
1 1
1 1 1
1
Grit Blower - Run-hour record
Reset of Hour-Run meter
0
Grit Pump : On
Indicator
1
1
Grit Pump - To Start / Stop
Remote Control
1
1
Record number of Start / stop
Grit Pump : Trip
Indicator
1
1
Record number of Start / stop
Software counter / software Timer control operation by rotation. Record number of Start / stop Alarm (Fault Report)
Grit Pump - Run-hour record
Reset of Hour-Run meter
0
Grit Classifier : On
Indicator
1
1
Software counter / software Timer control operation by rotation. Record number of Start / stop
Grit Classifier - To Start / Stop
Remote Control
1
1
Grit Classifier : Trip
Indicator
1
1
Grit Classifier - Run-hour record
Reset of Hour-Run meter
0
Grit Auger : On
Indicator
1
1
Grit Auger : Trip
Sewage Treatment Plants
Indicator
1
Volume 4
1
Alarm (Fault Report)
Software counter / software Timer control operation by rotation.
Record number of Start / stop Alarm (Fault Report)
253
Description of Control Point (For Each Equipment)
AO
DI
DO
SCADA Control / Monitoring
AI
Description of Monitoring Point (For Each Equipment)
Analog (A)/ Digital (D)
Qty
Item
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
Grit Auger - To Start / Stop
Remote Control
1
1
Grit Auger - Run-hour record
Reset of Hour-Run meter
0
Grit Drum Screen : On
Indicator
1
1
Software counter / software Timer control operation by rotation. Record number of Start / stop
Remote Control
1
1
Grit Drum Screen : Trip Grit Drum Screen - To Start / Stop
Grit Drum Screen - Run-hour record
Reset of Hour-Run meter
0
Auxiliary
Software counter / software Timer control operation by rotation.
Indicator
1
1
Status
Indicator
1
1
Alarm (Fault Report)
Indicator
1
1
Alarm (Fault Report)
Reading
1
1
Record
Reading
1
1
Record
Reading
1
1
Indicator
1
1
Reading
1
1
Record
LV System Main LV Board Main Breaker : ON Main LV Board Main Breaker : TRIP (Earth Fault) Main LV Board Main Breaker : TRIP (Over Current) Main LV Board Main Breaker : Ampere Main LV Board Main Breaker : Voltage Room Temperature Monitoring / Alarm Bus Couple : ON
kWHr Meter: HT System
Bus Couple : OFF
HT Income Panel VCB : ON HT Income Panel VCB: TRIP (Earth Fault) HT Income Panel VCB: TRIP (Over Current) HT Income Panel VCB: Ampere
Battery Charger
HT Income Panel VCB: Voltage Battery Low
Room Temperature Monitoring / Alarm
254
Indicator
Indicator
Indicator
1
1
1
1
1
1
Alarm (Fault Report)
Status
Indicator
1
1
Alarm (Fault Report)
Indicator
1
1
Alarm (Fault Report)
Reading
1
1
Record
Indicator
1
1
Record (Alarm fault)
Reading
Indicator
1 1
1 1
Record
Record (Alarm Low)
Reading
1
1
Record / Alarm (High)
kWHr Meter Transformer System
Reading
1
1
Record
Transformer Pressure Alarm CO2 System TNB Room: CO2 Panel Activated Switch Gear: CO2 Panel Activated Transformer Room: CO2 Panel Activated
Indicator
1
1
Record / Alarm (High)
Transformer Temperature Alarm
Indicator
1
1
Record / Alarm (High)
Indicator
1
1
Record / Alarm (activated)
Indicator
1
1
Record / Alarm (activated)
Indicator
1
1
Record / Alarm (activated)
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Malaysian Sewerage Industry Guidelines
CO2 Panel DC supply Battery Low Gen Set System
Gen Set - Trip
Gen Set - Run
Gen Set - To Start / Stop (Remote) Gen Set - To Stop (Remote)
Gen Set - Run-hour record
Gen Set -Battery Charge
Gen Set -DC Battery Low
Gen Set -Diesel Fuel oil low
Surge Vessel Compressors System Air Compressor - Run
Air Compressor - Auto Mode
Air Compressor - Trip
Air Compressor - Manual Mode
Air Compressor - To Start / Stop Air Compressor - Run-hour record Surge Vessel Level Indicator
Fan : Manual
Surge Vessel Pressure Indicator Force Ventilation: Grit System Fan : Auto Fan : ON / OFF
Indicator Indicator Indicator
Indicator
Remote Start / Stop Remote Start / Stop Reset of Hour-Run meter Indicator Indicator
1
1
Record / Alarm (activated)
1
1
Record / Alarm (activated)
1
1
Record / Alarm (activated)
1
1
Record number of Start / stop
1
1
Alarm (Fault Report)
1
1
Software control / PLC
1
1
Software control / PLC
1
Software counter running hours
1
1
Record / Alarm (Fault)
1
1
Record / Alarm (Low)
1
Record / Alarm (Low)
Indicator
1
1
Record number of Start / stop
Indicator
1
1
Indicator
1
Indicator
Remote Control Reset of Hour-Run meter Level Measure Pressure Measure Indicator Indicator Indicator
Scrubber Fan : Auto Scrubber Fan : ON / OFF
Indicator Indicator
Indicator
Scrubber Fan : Trip Scrubber Fan : To Start / Stop
Aeration Blower
Indicator Remote Start / Stop
Blower - Trip
Indicator
Sewage Treatment Plants
Record / Alarm (activated)
Blower - Off (MCCB)
Gas Scrubber System
1
Blower - Run
Indicator Remote Start / Stop
1
Indicator
Fan : Trip Fan : To Start / Stop
Scrubber Fan : Manual
1
Indicator
DO
Indicator
DI
Main Switch Room: CO2 Panel Activated MCC Room: CO2 Panel Activated Gen Set- CO2 Panel Activated
SCADA Control / Monitoring
AO
Description of Monitoring Point (For Each Equipment)
Analog (A)/ Digital (D) AI
Description of Control Point (For Each Equipment)
Qty
Item
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
Indicator
Indicator
1 1
1 1
1
Alarm (Fault Report)
0
Software counter running hours
1
1
1
1
1 1
1
1
Status & Software counter running hours
1
1
1
1
1
1
1 1
1
1
1
1
1
1
1 1
1
Record number of Start / stop
1
Volume 4
1
1
1
1
Status & Software counter running hours Alarm (Fault Report)
Alarm (Fault Report)
Alarm (Fault Report)
Record non-operation hours
255
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
Blower - Ampere Blower - Voltage
Temperature Sensor
Blower - Temperature Air Flow Meter Air Flow Meter
Force Ventilation: Blower Room Fan : Manual
Fan : Trip
Fan : Run-Hour record
Fan : Auto Fan : ON / OFF
Fan : To Start / Stop
D.O. Meter D.O. Meter
Anoxic Mixer
Anoxic Mixer - Run Anoxic Mixer - Trip
Anoxic Mixer - Off (MCCB)
Anoxic Mixer - To Start / Stop
Anoxic Mixer - Run-hour record
Anoxic Mixer - Ampere
Anoxic Mixer - Voltage
Primary or Secondary Clarifier Clarifier - Run
Clarifier - Trip
Clarifier - Off (MCCB)
Clarifier - To Start / Stop
Clarifier - Run-hour record
Clarifier - Ampere
256
Clarifier - Voltage
Reset of Hour-Run meter Measure Measure
1
Software control / PLC
1
1
0
1
1
RTU via RS-485 Serial Link Software counter / software Timer control operation by rotation. Record when operation
Measure
1
Measure
1
Indicator Indicator Indicator Remote Start / Stop Reset of Hour-Run meter
Indicator Indicator
Remote Start / Stop Reset of Hour-Run meter Measure Measure
Indicator Remote Start / Stop Reset of Hour-Run meter Measure
1
Record when operation
Record & Alarm (High Temp)
Record & Alarm (low level)
1
1
1
1
1
1
Status & counter no. of start / stop Alarm (Fault Report)
1
1
1
1
1
1
1
1
1
Status & counter no. of start / stop Alarm (Fault Report)
1
1
Software control / PLC
0
Software counter
1
1
Record when operation
1
1
Indicator
1
Indicator
Measure
1
1
Indicator
Measure
1
1
Indicator
DO
Blower - Run-hour record
DI
Blower - VSD Parameters
AO
Remote Start / Stop Speed Control
SCADA Control / Monitoring
AI
Blower - To Start / Stop
Analog (A)/ Digital (D) Qty
Item
Description of Control Point (For Each Equipment)
Description of Monitoring Point (For Each Equipment)
1
1
Record / Control Speed & Alarm (Low)
Record non-operation hours
Record when operation
1
1
1
1
1
Software control / PLC
0
Software counter
1
1
Record when operation
1
Volume 4
1
1
Software counter / software Timer control operation by rotation.
1
1
Status & counter no. of start / stop Alarm (Fault Report)
1
Record non-operation hours
Record when operation
Malaysian Sewerage Industry Guidelines
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
Description of Control Point (For Each Equipment)
Analog (A)/ Digital (D) AI
AO
DI
DO
SCADA Control / Monitoring
Qty
Item
Description of Monitoring Point (For Each Equipment)
Pump - Run
Indicator
1
1
Pump - Trip
Indicator
1
Pump - To Start / Stop
1
1
Software control / PLC
Pump - Run-hour record
0
Software counter
Pump - Ampere
Indicator Remote Start / Stop Reset of Hour-Run meter Measure
1
Status & counter no. of start / stop Alarm (Fault Report)
1
1
Record when operation
RAS/WAS Flow Rate Meter
Pump - Off (MCCB)
Pump - Volt
Sludge Flow Meter
RAS/WAS Flow Rate Totalizer
Flow Meter System
Flow Meter (Data record of flow rate)
Measure
1
1
Measure
1
Measure
1
1
1 1
1
Record non-operation hours
Record when operation
Record Record
Measure
1
1
Record
Flow Meter (Totalizer) Gravity Thickener
Measure / Reset
1
1
G. Thickener - Run
Indicator
1
1
G. Thickener - Trip
Indicator
1
1
SCADA Software Accumulator Status & counter no. of start / stop Alarm (Fault Report)
G. Thickener - To Start / Stop
1
1
G. Thickener - Run-hour record
0
G. Thickener - Ampere
1
1
G. Thickener - Off (MCCB)
G. Thickener - Voltage Thickened Sludge Digester Feed Pump: Primary & Secondary
Indicator Remote Start / Stop Reset of Hour-Run meter Measure Measure
1
1
1
1
Feed Pump - Run
Indicator
1
1
Feed Pump - Trip
Indicator
1
1
Feed Pump - To Start / Stop
1
1
Feed Pump - Run-hour record
0
Feed Pump - Ampere
Indicator Remote Start / Stop Reset of Hour-Run meter Measure
1
1
Feed Pump - VSD Parameters
Speed Control
1
1
Sludge Feed Flow Rate Meter
Measure
1
1
Feed Pump - Off (MCCB)
Feed Pump - Voltage Sludge Flow Meter
Sludge Feed Flow Rate Totalizer
Gas Blower
Measure
Measure
1
1
1
1
1
1
1
Gas Blower - Trip
Indicator
1
1
Sewage Treatment Plants
Volume 4
1
Record non-operation hours Software control / PLC Software record of running hours Record when operation
Record
1 1
Status & counter no. of start / stop Alarm (Fault Report)
Indicator Indicator
Record when operation
Gas Blower - Run Gas Blower - Off (MCCB)
Software control / PLC Software record of running hours Record when operation
Record when operation Speed control : RTU via RS-485 Serial Link
Record non-operation hours
Record
Status & counter no. of start / stop Alarm (Fault Report) Record non-operation hours
257
Gas Blower - Run-hour record
Gas Blower - Ampere
Gas Blower - Temperature
Measure
Gas Blower - Voltage Temperature Sensor Gas Flow Meter
Gas Flow Meter Digester Gas Detector Meters
Measure
Measure
DO
Remote Start / Stop Reset of Hour-Run meter Measure
DI
Gas Blower - VSD Parameters
SCADA Control / Monitoring
AO
Analog (A)/ Digital (D) AI
Description of Control Point (For Each Equipment)
Description of Monitoring Point (For Each Equipment)
Qty
Item
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
1
1
0
1
1
Speed control : RTU via RS-485 Serial Link Software record of running hours Record when operation
1
1
Record & Alarm (High)
1
1
1
1
Record when operation
Record
Record & Alarm (Detection & Fault) Record & Alarm (Detection & Fault) Record & Alarm (High-Low & Fault) Record & Report Record & Alarm (High-Low & Fault) Alarm (High)
H2S Meter at Dewatering House
Measure
1
1
Methane Gas Meter
Measure
1
1
PVRV Sensor Meter
Measure
1
1
Internal Digester Gas Analyzer Floating Roof Gas Holder
Measure
1
1
Floating Roof Level
Measure
1
1
High Lever Alarm
Indicator
1
1
PVRV Sensor Meter
Measure
Alarm (Low) Record & Alarm (High-Low & Fault)
Indicator
1
1
Record & Timer
Indicator
1
1
Record & Timer
Indicator
1
1
Indicator
1
1
Program Control operation
Indicator
1
1
Status & counter no. of start / stop
Indicator
1
1
Alarm (Fault Report)
1
1
Software control / PLC
1
1
Software control / PLC
1
1
Low Lever Alarm
Gas Flare System Gas Control Actuator Open Gas Control Actuator Close Gas Control Actuator Manual Gas Control Actuator Auto
Indicator
Valve: Full Valve: Full Valve: Valve:
Gas Control Actuator Valve: ON
1
1
Gas Control Actuator Valve: TRIP Gas Control Actuator Valve: To Turn Clockwise Gas Control Actuator Valve: To Turn Counter-Clockwise
Flare Igniter : Manual
Indicator
1
1
Flare Igniter : ON
Indicator
1
1
Pilot Light Igniter
Flare Igniter : Auto
Remote Start / Stop Remote Start / Stop Indicator Indicator
1
1
Record & Alarm (flame distinguished)
Program Control operation
Flare Indicator
Indicator
1
1
Pressure Indicator: Inlet
Measure
1
1
Program Control operation Record & Alarm (flame distinguished) Record & Report Fault
Belt Press Feed Pump - Manual
Indicator
1
1
258
Pressure Indicator: Discharge Sludge Feed Pump to Belt Press
Measure
1
Volume 4
1
Record & Report Fault
Malaysian Sewerage Industry Guidelines
Description of Control Point (For Each Equipment)
AO
DI
DO
SCADA Control / Monitoring
AI
Description of Monitoring Point (For Each Equipment)
Analog (A)/ Digital (D) Qty
Item
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
Belt Press Feed Pump - Auto
Indicator
1
1
Belt Press Feed Pump - Run
Indicator
1
1
Belt Press Feed Pump - Trip Belt Press Feed Pump - Off (MCCB) Belt Press Feed Pump - To Start/ Stop Belt Press Feed Pump - Run-hour record Belt Press Feed Pump - Ampere
Indicator
1
1
Program Control operation Status & counter no. of start / stop Alarm (Fault Report)
Indicator
1
1
Record non-operation hours
1
1
Software control / PLC
0
1
1
Speed Control
1
1
Indicator
1
1
Belt Press Feed Pump - Voltage Belt Press Feed Pump - VSD Parameters Belt Press Compressors System
Air Compressor - Trip
Air Compressor - Run
Air Compressor - Auto Mode
Air Compressor - Manual Mode
Air Compressor - To Start/Stop/ Stop Air Compressor - Run-hour record Sludge Cake Conveyor
Screen c/v - Trip
Screen c/v - Run
Screen c/v - Auto Mode
Screen c/v - Manual Mode
Screen c/v - To Start / Stop / Stop
Screen c/v - Run-hour record
Belt Backwash Washwater Pumps Washwater Pump - Run
Washwater Pump - Auto Mode
Washwater Pump - Trip
Washwater Pump - Manual Mode
Washwater Pump - To Start / Stop / Stop
Remote Start / Stop Reset of Hour-Run meter Measure Measure
1
Indicator
1
Indicator
1
Indicator
1
Remote Control Reset of Hour-Run meter Indicator Indicator Indicator Remote Control
1 1 1
Record when operation Speed control : RTU via RS-485 Serial Link
Alarm (Fault Report)
Record number of Start / stop Program Control operation
1
1
Software control / PLC
0
Software counter running hours
1
1
Alarm (Fault Report)
1 1
Indicator
1
Software record of running hours Record when operation
1
1 1
Program Control operation
Indicator
1
1
Record number of Start / stop
Indicator
1
1
Program Control operation
Indicator
1
1 1
1
Record number of Start / stop
0
1
Reset of Hour-Run meter
1
Software counter / Interlock with screen operation with delay off.
Indicator
1
Alarm (Fault Report)
Remote Control
1
1
Washwater Pump - Run-hour record
Reset of Hour-Run meter
0
Polymer Preparation Unit
Software counter / Interlock with screen operation with delay off.
Polymer Mixing - Trip
Indicator
1
1
Alarm (Fault Report)
Polymer Mixing - Run
Polymer Mixing - Auto Mode
Polymer Mixing - Manual Mode
Polymer Mixing - To Start / Stop
Sewage Treatment Plants
Indicator
1
Indicator Indicator
1
Remote Control
1 1
Volume 4
1 1 1
1
Software control / PLC
Record number of Start / stop Program Control operation
Software control / PLC
259
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
Description of Control Point (For Each Equipment)
AI
AO
DI
DO
SCADA Control / Monitoring
Qty
Item
Description of Monitoring Point (For Each Equipment)
Analog (A)/ Digital (D)
Polymer Mixing - Run-hour record
Reset of Hour-Run meter
0
Software counter / Interlock with screen operation with delay off
Polymer Dilution Skid - Trip
Indicator
1
1
Alarm (Fault Report)
Polymer Dilution Skid - Run
Polymer Dilution Skid - Auto Mode Polymer Dilution Skid - Manual Mode Polymer Dilution Skid - To Start/ Stop
Indicator
1
1
Record number of Start / stop
Indicator
1
1
Program Control operation
Indicator
1
1
Remote Control
1
1
Software control / PLC
Polymer Dilution Skid - Runhour record
Reset of Hour-Run meter
0
Software counter / Interlock with screen operation with delay off.
Fan : Manual
Indicator
1
1
Fan : Run
Indicator
1
1
Fan : Off
1
1
Fan : To Start / Stop
1
1
Fan : Run-Hour record
1
Indicator Remote Start / Stop Reset of Hour-Run meter
Status & counter no. of start / stop Alarm (Fault Report)
Software record of running hours
Force Ventilation: Sludge Feed & Dewatering Room Fan : Auto
Notes: AI = Analog Input Qty = Quantity
260
Indicator
1
1
AO = Analog Output DI = Digital Input
Volume 4
DO = Digital Output
Malaysian Sewerage Industry Guidelines
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
Attachment C - 3: Representation of SCADA Control Symbols Attachment C - 3: Representation of SCADA Control Symbols PUMPS & AERATION DEVICES PUMPS & AERATION DEVICES
OFF MODE
EQUIPMENT
PUMPS (Centrifugal)
PUMPS (Progressive Cavity) BLOWER
SURFACE AREATOR
Sewage Treatment Plants
234
ON MODE
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261
Malaysian Sewerage Treatment Plant
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
ACCESSORIES & FITTINGS ACCESSORIES & FITTINGS EQUIPMENT
OFF MODE
ON MODE
Valves (General)
BUTTERFLY VALVE
AGITATOR
CONVEYORS
CONVEYORS SCREW
262
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Third Edition Volume 4
Malaysian Sewerage Industry Guidelines
Page 235
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
Appendix C - Supervisory Control and Data Acquisition System (SCADA)
OTHERS OTHERS SYMBOLS
EQUIPMENT PLC CONTROLLER
WIRELESS COMMUNICATION
SCADA WORKSTATION
POWER TRANSMISSION
METER
COMPRESSOR
TANK
Sewage Treatment Plants
236
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263
Malaysian Sewerage Treatment Plant
Appendix D Duty and Standby Requirements
Appendix D - Duty and Standby Requirements
266
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Appendix D - Duty and Standby Requirements
Appendix D Table D1 Table D2 Table D3 Table D4
Duty and Standby Requirements
Duty and Standby Requirements for Activated Sludge Systems (Utilising Diffused Aeration)
Duty and Standby Requirements for Activated Sludge Systems (Utilising Mechanical Surface Aerator)
Duty and Standby Requirements for Rotating Biological Contactor Systems Duty and Standby Requirements for Trickling Filter Systems
Sewage Treatment Plants
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Appendix D - Duty and Standby Requirements
268
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Appendix D - Duty and Standby Requirements
Sewage Treatment Plants
Volume 4
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Appendix D - Duty and Standby Requirements
270
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Appendix D - Duty and Standby Requirements
Sewage Treatment Plants
Volume 4
271
Appendix E Glossary of Abbreviations
Appendix E - Glossary of Abbreviations
274
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Appendix E - Glossary of Abbreviations
Glossary of Abbreviations ABF
Activated Biofilter
AL
Aerated Lagoon
AS
Activated Sludge
ATU
Allyl Thio Urea
BOD
Biochemical Oxygen Demand
BOD5
Total Five Day Biochemical Oxygen Demand
CAS
Conventional Activated Sludge
CF
Certificate of Fitness
CMAL
Complete Mixed Aerated Lagoon
CMAS
Conventional Mode Activated Sludge
COD
Chemical Oxygen Demand
CPR
Cardio Pulmonary Resuscitation
DMF
Dual Media Filtration
DO
Dissolved Oxygen
DOE
Department of Environment
DOSH
Department of Occupational Safety and Health
DS
Deep Shaft
EA
Extended Aeration
EAMAS
Extended Aeration Mode Activated Sludge
F/M
Food to Microorganism ratio
FAL
Facultative Aeration Lagoon
FWSP
Facultative Waste Stabilisation Ponds
GRP
Glass Reinforced Plastic
HAZOP
Hazard and Operability Review
HRT
Hydraulic Retention Time
HRTF
High Rate Trickling Filter
MCRT
Mean Cell Residence Time
MLSS
Mixed Liquor Suspended Solids
MLVSS
Mixed Liquor Volatile Suspended Solids
Sewage Treatment Plants
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275
Appendix E - Glossary of Abbreviations
276
MOD
Modified Oxidation Ditch
MP
Maturation Pond
MS 1228
Malaysian Standard 1228: Code of Practice for Design and Installation of Sewerage Systems
OD
Oxidation Ditch
OP
Oxidation Pond
OASH
Occupational Safety and Health Act
PE
Population Equivalent
Qavg
Average Flow
Qpeak
Peak Flow
QRAS
Return Activated Sludge Flow
RAS
Return Activated Sludge
RBC
Rotating Biological Contactor
SBC
Submerged Biological Contactor
SBR
Sequential batch Reactor
SIRIM
Standards and Industrial Research Institute of Malaysia
SS
Suspended Solids
SPAN
Suruhanjaya Perkhidmatan Air Negara (National Water Services Commission)
SST
Secondary Settlement Tank
STP
Sewage Treatment Plant
TDH
Total Dynamic Head
TF
Trickling Filter
TOL
Total Organic Load
VSS
Volatile Suspended Solids
WAS
Waste Activated Sludge
Volume 4
Malaysian Sewerage Industry Guidelines
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