978-0131190825 Chapter 11 Part 1

Document Type
Homework Help
Book Title
Basic Environmental Technology: Water Supply-- Waste Management & Pollution Control 5th Edition
Jerry A. Nathanson M.S. P.E.
Review Question Page References
(1) - (7) 351 (13) 362
(2) 343 (8) 351 (14) 363
(3) 344 (9) 353 (15) 364
(4) 344 (10) 354 (16) 368
(5) 347 (11) 356 (17) 369
(6) 350 (12) 359 (18) 370
(24) www.epa.gov/epaoswer/osw/cleanup.htm
(25) www.swana.org (26) www.envirosources.com
(19) 372
(20) 372
(21) 370
(22) 374
(23) 374
Solutions to Practice Problems
2. volume reduction = {(8 - 1)/8} x 100 = 87.5 88%
3. volume reduction = {(10 - 1)/10} x 100 = 90%
4. % volume reduction = {(18 - 2)/18} x 100 = 88.9% 89% (Eq. 11-1)
5. 50,000 people x 8 Ib/person/d x 365 d/yr = 146,000,000 Ib/yr
146,000,000 Ib/yr ÷ 1200 Ib/yd3 = 121,667 yd3/yr
6. 240 000 x 25 N/person/d x 365 d/yr = 2 190 000 000 N/yr
2 190 000 000 N/yr ÷ 10 000 N/m3 = 219 000 m3/yr
Depth = 273 750 m3/100 000 m2 2.7 m
7. 20,000 x 5 = 100,000 lb/d of refuse
8. 30,000 x 30 = 900,000 N/d of refuse
300 m3/d 12 m3/truck 25 truckloads per day
9. Available volume = 10 ac x 43,560 ft2/ac x 50 ft = 21,780,000 ft3
10. Available volume = 12 ha x 10 000 m2/ha x 20 m = 2 400 000 m3
11. 35 000 x 30 x 365 = 383 250 000 N/yr = 383 250 kN/yr
12. 70,000 x 4 x 365 = 102,200,000 Ib/yr
13. 30,000 people x 5 Ib/person/d x 365 d/yr = 54,750,000 Ib/yr
14. 50 000 people x 20 N/person/d x 365 d/yr = 365 000 000 N/yr
365,000,000 N/yr ÷ 8000 N/m3 = 45 625 m3/yr
(There are no Practice Problems for Chapter 12.)
Review Question Page References
(1) 416 (11) 421 (21) 429
(40) www.epa.gov/globalwarming/news/index.html
(31) 443
* At 1100 m, the air parcel temperature will be 18 - 1 = 17 degrees while the surrounding air will be
18 + 2 = 20 degrees. Since the cooler air parcel is denser than the surrounding air, it will descend back
towards its original position. At 800 m, the air parcel will be 18 + 2 = 20 degrees while the surrounding
air will be 18 - 4 = 14 degrees. Since the warmer air parcel is lighter than the surrounding air, it will rise
back toward its original position. The atmosphere is stable under these conditions (an inversion).
1. (a) superadiabatic, since the lapse rate exceeds -1 degree/100 m
2. (a) subadiabatic
3. 80 μg/m3 x 1 mg/1000 μg = 0.080 mg/m3
4. 100 μg/m3 x 1 mg/1000 μg = 0.10 mg/m3
5. Molecular weight of CO = 12 + 16 = 28
7. 1.8% x 10,000 ppm/1% = 18,000 ppm
8. 0.1% x 10,000 ppm / 1% = 1,000 ppm
9. Area = πD2/4 = π(0.5)2/4 = 0.1963 ft2
10. Average air flow = (54 + 48)/2 = 51 ft3/min
11. E1 =100 x (1- e-0.15x6000/200) = 98.9%
Review Question Page References
(1) 463 (8) 466 (15) 471
(2) 464 (9) 466 (16) 472
(3) 464 (10) 468 (17) 472
(4) 464 (11) 467 (18) -
(5) 464 (12) 469 (19) 473
(6) 465 (13) 468 (20 474
(7) 465 (14) 470 (21) 475
Solutions to Practice Problems
(22) 475
(23) 475
(24) 475
(25) 476
(26) 476
(27) www.nonoise.org/library/probresp.htm#p6
(28) http://ftp.loc.gov/pub/thomas/clos/h536.ih.txt
(29) www.envirosources.com
1. Distance = velocity x time, so time = distance/velocity
2. Distance = velocity x time, so time = distance/velocity
3. From Eq. 14-1, v = λ x f , and 1500 = λ x 15,000, so λ = 0.1 m
9. 90 dBA; the 75 dBA sound is masked by the 90 dBA sound
10. Using Figure 14.4, 90 + 0.5 = 90.5 dBA
15. (See Example 14.5 for procedure)
dBA Rank % exceeded
16. dBA Rank % exceeded
1. Engineering drawings of a wastewater collection system include:
(a) tax maps and population densities
(b) specifications of constructions materials
(c) plan and profile views showing pipe location, size and slope
(d) construction cost estimates
(e) instructions for pipeline installation and maintenance
2. An inverted siphon is a
(a) device commonly Used in water distribution systems
(b) sewer that drops below the HGL to avoid an obstruction
(c) control device Used in a wastewater pumping station
(d) CSO bypass around a wastewater treatment plant
(e) none of the above
3. Exfiltration testing is used to
(a) ensure noxious gases do not leak out of a sewer line
(b) determine the pumping capacity of water supply wells
(c) check the structural integrity of underground pipelines
(d) test sanitary sewers for watertightness or leaks
(e) determine the fire flow capacity of a water main
Crown corrosion in sanitary sewers is caused by
(a) bacteria that produce hydrogen sulfide gas and sulfuric acid
(b) abrasion of the pipe wall by suspended solids in the sewage
(c) normal wear and tear of the pipeline
(d) excessively high wastewater flow velocities
(e) acidic industrial wastewater
5. A check valve is commonly used for
(a) tight shutoff of flow in a water main
(b) throttling the flow in a water main
(c) controlling the flow of wastewater in a gravity sewer
(d) protection of maintenance workers in drop manholes
(e) prevention of backflow in pump discharge piping after shut off
6. The main function of distribution storage in a water supply system is
(a) provision of reserve supplies for emergencies
(b) reduction of required pipe sizes and capacities
(c) to meet hourly variations in water demand
(d) to stabilize pressures in the water distribution system
(e) all of the above
7. Thermal stratification may significantly affect the
(a) rate of flow in a pipe
(b) capacity of a well
(c) peak urban runoff rate
(d) drought flow in a stream
(e) water quality in a lake or reservoir
8. Pumps that can operate under a wide variety of operating pressures are
(a) centrifugal
(b) screw-feed
(c) air lift
(d) rotary displacement
(e) reciprocating positive displacement
9. Which of the following statements about centrifugal pumps is true?
(a) With the valve in the discharge piping closed, the rotating impeller churns
in the water, causing the pressure at the outlet to rise to the shut-off head.
(b) If the discharge valve is gradually opened, allowing increasing flow of
water, the pump head decreases.
(c) When the pump lifts water from a reservoir into a piping system, the
resistance of flow at various rates of discharge is described by a system head
(d) With increasing rate of discharge, pump efficiency rises to an optimum
value and then slowly falls.
(e) All of the above.
10. A equivalent pipe is an
(a) average length of pipe replacing a looped pipe system
(b) average pipe diameter replacing a series or parallel pipe system
(c) average pipe that has the same flow rate as a given real system
(d) theoretical pipe that has a minimum head loss for a given flow
(e) theoretical pipe that replaces a section of a real system so that
the head loss in the two systems are identical for any flow
11. Flow rates in water mains or force mains may be measured by using a
(a) Parshall flume
(b) rectangular weir
(c) v-notch weir
(d) venturi meter
(e) all of the above
12. The three-edge bearing test is used to determine the
(a) backfill load on a buried pipe
(b) wheel load on a buried pipe
(c) capacity of a fire hydrant
(d) coefficient of runoff for a drainage basin
(e) crushing strength of a pipe
13. The streamflow used for designing a water supply reservoir is the
(a) flood flow
(b) minimum flow
(c) one-in-ten-year minimum seven consecutive day low flow
(d) average flow
(e) none of the above
14. The spring overturn or spring circulation is associated with
(a) the formation of the epilimnion and hypolimnion in a lake
(b) high infiltration flows in a sanitary sewer system
(c) change in potable water demand or consumption
(d) mixing of lake water due to thermal destratification
(e) the decrease in dissolved oxygen levels in nutrient-rich lakes
15. A combined sewer collects
(a) wastewater from laterals and trunk sewers
(b) flows from sanitary sewers and force mains
(c) stormwater and infiltration flows
(d) industrial and commercial wastewater
(e) domestic wastewater and stormwater
16. A major difference in the design of sanitary and storm sewers is
(a) sanitary sewers are designed to flow half full
(b) storm sewers may surcharge and overflow periodically
(c) storm sewers are designed to flow half full
(d) sanitary sewers may surcharge and overflow periodically
(e) none of the above
17. If a storm is said to have a recurrence interval of 25 years, then the
(a) probability of it occurring in any one year is 25 percent
(b) probability of it occurring in any one year is 4 percent
(c) probability of it occurring in any one year is 0.25 percent
(d) probability of it occurring in any one year is 75 percent
(e) none of the above
18. The advantages of tight shut-off and low head-loss apply to
(a) gate valves
(b) check valves
(c) magnetic flow meters
(d) butterfly valves
(e) venturi meters
19. A stage-discharge curve is a
(a) plot of minimum streamflow and probability of occurrence
(b) graph of water level in a river and corresponding flow rate
(c) plot of rainfall intensity and duration of rainfall events
(d) graph of pumping head and pumping flow rate
(e) plot of hourly water consumption versus time of day
20. The time of concentration of a drainage basin is the
(a) longest time required for water to flow to the basin outlet
(b) time during which the storm intensity will not be exceeded
(c) duration of a precipitation event in the drainage basin
(d) service life of the drainage basin drainage infrastructure
(e) none of the above
21. Total dynamic head (TDH) in a pumping system is the
(a) static head plus velocity head
(b) velocity head plus friction head plus atmospheric pressure head
(c) static head plusfriction head plus velocity head
(d) friction head plus velocity head plus suction lift
(e) none of the above
22. The operating point of a centrifugal pump is the intersection of the
(a) system head curve and the pump efficiency curve
(b) system head curve and pump characteristic curve
(c) pump characteristic curve and pump efficiency curve
(d) pump characteristic curve and intensity-duration curve
(e) mass diagram and pump efficiency curve
23. The characteristic curve of a centrifugal pump shows that
(a) pumping head decreases as flow rate increases
(b) flow increases as pumping head increases
(c) pump efficiency varies inversely with the flow rate
(d) power output increases as flow rate decreases
(e) none of the above
24. If two centrifugal pumps are operating in series in a system,
(a) total head equals the sum of the heads for each pump
(b) total flow rate equals the sum of the flows through each pump
(c) both the above
(d) the flow rate is more than twice the original flow
(e) none of the above
25. Turbidity is an important water quality parameter because
(a) of esthetic reasons - consumers demand crystal clear water
(b) high turbidity makes filtration more difficult and expensive
(c) turbidity can interfere with the disinfection process
(d) all of the above
(e) none of the above
26. The presence of iron and/or manganese in water causes
(a) "blue babies", or methemoglobinemia
(b) scale deposits in plumbing
(c) tooth decay
(d) depletion of dissolved oxygen
(e) none of the above
27. The MPN is the result of which of the following laboratory tests?
(a) membrane filter
(b) fermentation tube
(c) biochemical oxygen demand
(d) dissolved oxygen
(e) turbidity
28. The theoretical detention time of a sedimentation tank is equal to
(a) flow rate divided by tank volume
(b) tank volume divided by flow rate
(c) overflow rate divided by tank surface area
(d) tank surface area divided by overflow rate
(e) none of the above
29. The process of adding chemicals to water to aid in sedimentation is
(a) bio-precipitation
(b) coagulation
(c) disinfection
(d) aeration
(e) softening
30. The term “flocculation” in water treatment refers to
(a) slow mixing of the water with chemicals
(b) complete destruction of pathogenic bacteria
(c) periodic cleaning of rapid sand filters
(d) metabolism of organic waste by bacteria
(e) injection of compressed air to increase DO levels
31. A type of filter commonly used for municipal water treatment is the
(a) trickling filter
(b) diatomaceous-earth filter
(c) closed pressure filter
(d) open mixed-media filter
(e) membrane filter
32. Manholes in wastewater collection systems should be placed
(a) no more than 30 meters apart
(b) at each pipe intersection and change of pipe slope or size
(c) at intervals no closer than 200 meters
(d) with inverts no more than 2 meters below grade
(e) all of the above
33. The "strength" of sewage is characterized primarily by its
(a) BOD and turbidity
(b) turbidity and odor
(c) suspended solids and BOD
(d) MPN and coliform count
(e) TDH and BOD
34. The BOD of wastewater is determined by
(a) evaporating the sample and weighing the residue
(b) filtering the sample and weighing the trapped solids
(c) heating the sample for 5 days and then measuring the DO
(d) measuring the DO consumed in a diluted sample after 5 days
(e) measuring the suspended solids after 5 days of settling
35. Bar screens and grit chambers are used
(a) only in primary wastewater treatment plants
(b) in most municipal wastewater treatment plants
(c) very rarely due to applications of modern technology
(d) only in advanced wastewater treatment plants
(e) in most municipal water supply facilities
36. Grit chambers are used to
(a) digest organic solids in sewage sludge
(b) reduce primary wastewater effluent BOD levels
(c) remove suspended solids that may damage equipment
(d) remove colloidal solids that cannot be removed by sedimentation
(e) none of the above
37. Mixed liquor is a term used to describe the
(a) contents of a sludge digestion tank
(b) contents of an activated sludge aeration tank
(c) film of microorganisms growing on a trickling filter
(d) drink a treatment plant operator has with his or her lunch
(e) contents of a sludge thickening tank
38. In the trickling filter process
(a) primary effluent fIows over stones coated with microorganisms
(b) raw sewage flows over stones coated with purifying chemicals
(c) sewage is mixed with flocs of microorganisms and then filtered
(d) secondary effluent trickles through a sand filter to "polish" it
(e) none of the above
39. A process in which sewage is aerated for about 24 hours is called
(a) step aeration
(b) contact stabilization
(c) extended aeration
(d) advanced treatment
(e) none of the above
40. A vacuum filter is used to
(a) digest sludge
(b) dewater sludge
(c) purify drinking water
(d) test for coliforms
(e) test for suspended solids
41. Tertiary treatment may be used to
(a) soften municipal water supplies
(b) remove toxic chemicals from wastewater
(c) remove plant nutrients from wastewater
(d) prepare sludge for final disposal
(e) prepare crystal clear drinking water
42. The percolation or perc test is important in the design of
(a) activated sludge systems
(b) trickling filter systems
(c) water disinfection systems
(d) subsurface sewage disposal systems
(e) water desalting systems
43. A 12-inch pipe and an 18-inch intersect at a manhole. If the invert elevation of
the 12-inch pipe is 100.00 ft, the invert of the 18-inch pipe should be
(c) 99.50
(e) 98.50
44. Compared to sanitary sewers, storm sewers are usually
(a) in shallower trenches
(b) of smaller pipe diameter
(c) less efficient
(d) in deeper trenches
(e) none of the above
45. The most commonly used pump in water and sewage systems is the
(a) centrifugal pump
(b) screw-feed pump
(c) air lift pump
(d) rotary displacement pump
(e) reciprocating displacement pump
46. Flow rates in open channels may be determined by using a
(a) Parshall flume
(b) rectangular weir
(c) v-notch weir
(d) any of the above
(e) none of the above
47. The minimum recommended size for lateral sanitary sewers is
(a) 4 in (100 mm)
(b) 6 in (150 mm)
(c) 8 in (200 mm)
(d) 10 in (250 mm)
(e) 12 in (300 mm)
48. By what percent should backwash water expand a sand filter bed?
(a) 0 -10
(b) 10 - 20
(c) 20 - 30
(d) 30 - 40
(e) 40 - 50
49. Compared to surface water, ground water usually contains
(a) a higher mineral content
(b) more microorganisms
(c) less dissolved minerals
(d) less fluorides
(e) less hydrogen sulfide, carbon dioxide, and methane
50. The objectionable feature of iron and manganese in drinking water is
(a) health hazard
(b) staining of plumbing fixtures
(c) mottled teeth
(d) scale deposits on plumbing fixtures
(e) none of the above
51. Water treatment filters remove or reduce
(a) color
(b) tastes and odors
(c) calcium and magnesium sulfates
(d) carbon dioxide
(e) turbidity
52. Compared to groundwater water, surface water usually contains more
(a) dissolved minerals
(b) microorganisms
(c) dissolved minerals
(d) fluorides
(e) hydrogen sulfide
53. A combined wastewater collection system may carry
(a) sanitary sewage and industrial sewage
(b) stormwater from both urban and rural areas
(c) stormwater and industrial sewage
(d) sanitary sewage, industrial sewage, and stormwater
(e) sanitary sewage and stormwater

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