1-1
CHAPTER 1 SOLUTIONS 1-1
Total daily withdrawal Given: Population in 2000 = 281,421,906 Solution: a. Using the total daily withdrawal of 5,400 Lpcd: (281,421,906 people)(5,400 Lpcd) = 1.52 x 1012 L · d-1 b. Converting to m3 1.52 × 1012 L · d -1 = 1.52 × 10 9 m 3 · d -1 3 1000L · m
1-2
Estimate per capita withdrawal for public supply Given: Population data from 1950 to 2000 and corresponding public supply withdrawal Solution: a. Use a spreadsheet to estimate the withdrawal
Population
Withdrawal, m3/d
Year
Withdrawal, Lpcd
151325798 179323175 203302031 226542203 248709873 281421906
5.30E+07 7.95E+07 1.02E+08 1.29E+08 1.46E+08 1.64E+08
1950 1960 1970 1980 1990 2000
350.24 443.33 501.72 569.43 587.03 582.75
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1-2
Liters per capita per day
Problem 1-2:Per Capita Daily Water Withdrawal for Public Supply 650.00 600.00 550.00 Estimated = 575 Lpcd 500.00 450.00 400.00 350.00 300.00 250.00 200.00 150.00 100.00 50.00 0.00 1940 1950 1960 1970 1980 1990 2000 2010 Year Fig ure S-1-2: Per capita daily water withdrawal 1-3
Additional average daily water production required Given: 280 houses and, from text: 1,320 L · d-1 · house-1 Solution: (280 houses)(1,320 L · d-1 · house-1) = 3.7 x 105 L · d-1
1-4
Additional average water production required with low-flush toilets Given: 320 houses that have low flush valves that reduce water consumption by 14% and, from text, 1,320 L · d-1 · house-1 Solution: Additional demand = (320 houses)(1,320 L · d-1 · house-1)(1 – 0.14) = 3.18 x 105 L · d-1
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1-3
1-5
Repeat Prob. 1-3 for peak demand Given: 280 metered houses, AWWA average Solution: a. From text: peak hour = 5.3(avg. day) (5.3)(280 houses)(1,320 L · d-1 · house-1) = 1.96 x 106 or 2 x 106 L · d-1 at the peak hour
1-6
Water lost (in liters) in one year Given: One drop per second, 0.150 mL per drop Solution: (0.150 mL · s-1)(86,400 s · d-1)(365 d · y-1)(1 x 10-3 L · mL-1) = 4,730 L · y-1
1-7
Monthly cost of not repairing valve Given: Valves deliver 130.0 L · min-1, Water cost = $0.45 per cubic meter Solution: a. Assuming 30 d · mo-1 (130.0 L · min-1)(1440 min · d-1)(30 d · mo-1)(1 x 10-3 m3 · L-1) = 5,616 m3 · mo-1 (5,616 m3 · mo-1)($0.45 m-3) = $2,527.20 or $2,530 mo-1
1-8
Value of water lost Given: Year 2000 data from Prob. 1-2, 15% water loss, cost of water = $0.45 m-3 Solution: a. Amount of water lost (1.6 x 108 m3 · d-1)(0.15) = 2.4 x 107 m3 · d-1 b. Value (2.4 x 107 m3 · d-1)($0.45 m-3) = $1.08 x 107 or $1.1 x 107 d-1
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1-4
1-9
Cost of bottled water Given: 0.5 L bottle of water costs $1.00 Solution: a. Convert L to m3 0 .5 L = 0.0005 or 5.0 x 10-4 m3 −3 1000L ⋅ m
b. Cost $1.00 = $2 × 10 3 or $2000 m-3 −4 3 5.0 × 10 m
1-10
Daily per capita withdrawal for South Carolina Given: USGS circular 1268 at /usgs.gov Solution: a. From the web site Domestic withdrawal for SC = 63.5 x 106 gal · d-1 Population = 4,010 x 103 b. Per capita 63.5 × 10 6 gal ⋅ d −1 = 59.94 Lpcd 4010 × 10 3 people 0.2642gal ⋅ L−1
( 1-11
)(
)
Lowest domestic withdrawal in the world Given: Pacific Institute web site (www.worldwater.org/table2.html) Solution: a. From the web site column labeled “Domestic Use” in m3 · p-1 · y-1 Gambia and Haiti tied at 1 m3 · p-1 · y-1 b. Convert to Lpcd
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1-5
(1m
3
)(
)
· p -1 · y -1 1000L ⋅ m 3 = 2.74 or 3 Lpcd 365d ⋅ y −1
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1-6
CHAPTER 1 DISCUSSION QUESTIONS 1-1
Defining hypothesis, theory, law Given: Explanation to a non-scientist Solution: A hypothesis is a statement that under certain circumstances certain phenomena may be observed. A set of generalizations that may be tied together under a given set of assumptions are formulated as a theory. Theories that have gained acceptance over a long period of time are known as laws.
1-2
Per capita water consumption Given: requirements to determine water consumption for local college or university Solution: Data to be collected include population served and the average water use for the institution.
1-3
Internet search Given: Clean Air Act and requirements to identify subject matter of Title II, chemical name of first hazardous air pollutant under Title III, last year that carbon tetrachloride can be produced. Solution: Title II addresses mobile sources. First hazardous air pollutant is acetaldehyde. 1999 was the last year that carbon tetrachloride could be produced.
1-4
URL for regulations Given: Federal Register and Code of Federal Regulations Solution: Find Federal Register at www.epa.gov/fedrgstr
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1-7
Find Code of Federal Regulations at www.epa.gov/epahome/cfr40.htm 1-5
Shiny Plating Co. ethics problem Given: Long ethics problem dealing with Shiny Plating Company Solution: In the interest of waste minimization, the company should install the pollution control equipment. The two year payback is reasonable. “Lack of capital and high interest rates,” are common excuses for not installing control equipment. The short payback time is indicative of long term profitability of the control device.
1-6
Leather tannery ethics problem Given: Long ethics problem dealing with leather tannery Solution: Select answer A. The discharge was illegal and not reporting is likewise illegal. Both professional ethics and environmental ethics require the choice.
NOTE: Discussion Questions 1-7 through 1-10 appeared as a survey in Chemical Engineering in 1970/1971. The responses were collected and tabulated. Because of changes in the law as well as society’s more progressive attitude toward and understanding of environmental ethics, the 1970/1971 responses are, at best, an anachronism. The answers provided below are the author’s based current law as well as our understanding of environmental ethics in the 21st century. 1-7
The correct response is A. Using Table 1-5 as a guide, this is in keeping with the 1st, 2nd, and 4th canons. Since the mid-1980s, all point source discharges must have an NPDES permit. This plant would be in violation if they did not have a permit to discharge. Part B: I would expect that most engineers would choose A but a survey of your class’ response would be a way to stimulate discussion and interest.
1-8
Based on environmental ethics, B is the correct choice. Using Table 1-5: 1st, 2nd, and 4th canons Part B: A is the correct choice based on environmental ethics.
1-9
The correct response is A. Besides being good environmental ethics, numerous environmental laws and regulations (TOSCA, the toxic release inventory –Form R, and Sorbane-Oxley Act) will force release of the information once the plant is in operation even if the permitting process does not reveal it. Under Sorbane-Oxley the corporate
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1-8
management may be liable for civil and criminal penalties for not revealing the information. 1-10
Based on environmental ethics, the correct answer is D. Although the community discharge is into the ocean, none of the arguments given by the engineer are correct today. Manufacturers in the United States have eliminated phosphorus builders from their products. Other sources of phosphorus are controlled by treatment at the wastewater treatment facility. The ocean discharge approach is only valid if the discharge is sufficiently distant from the tidal areas to prevent harm. This issue is not addressed in the problem statement.
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