MATHEMATICS MANUAL FOR WATER AND WASTEWATER TREATMENT PLANT OPERATORS - PART 5 docx
Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (2.23 MB, 225 trang )
Part V
Workbook Practice Problems
L1675_C34.fm Page 345 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
34
Workbook Practice Problems
TOPICS
• Basic Math Operations (Problems 1 to 43)
• Fundamental Operations (Water/Wastewater) (Problems 1 to 342)
• Water Treatment Calculations (Problems 1 to 457)
• Wastewater Treatment Calculations (Problems 1 to 574)
• Laboratory Calculations (Water and Wastewater) (Problems 1 to 80)
Note:
Answers to practice problems can be found in the Appendix.
BASIC MATH OPERATIONS (PROBLEMS 1 TO 43)
D
ECIMAL
O
PERATIONS
1. 90.5
¥
7.3 =
2. 9.556
¥
1.03 =
3. 13 ÷ 14.3 =
4. 8.2 ÷ .96 =
5. 2 ÷.053 =
L1675_C34.fm Page 347 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
348
Mathematics for Water/Wastewater Treatment Plant Operators
6. Convert 3/4 into a decimal.
7. Convert 1/6 into a decimal.
8. Convert 3/8 into a decimal.
9. Convert .13 into a fraction.
10. Convert .9 into a fraction.
11. Convert .75 into a fraction.
12. Convert .245 into a fraction.
P
ERCENTAGE
C
ALCULATIONS
13. Convert 15/100 into a percent.
L1675_C34.fm Page 348 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
Workbook Practice Problems
349
14. Convert 122/100 into a percent.
15. Convert 1.66 into a percent.
16. Convert 4/7 into a percent.
17. A 100% decline from 66 leaves us with how much?
F
IND
X
18. If
x
– 6 = 2, find
x
.
19. If
x
– 4 = 9, find
x
.
20. If
x
– 8 = 17, find
x
.
21. If
x
+ 10 = 15, find
x
.
L1675_C34.fm Page 349 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
350
Mathematics for Water/Wastewater Treatment Plant Operators
22. If
x
/3 = 2, find
x
.
23. Solve for
x
when
x
/4 = 10.
24. If 4
x
= 8, find
x
.
25. If 6
x
= 15, find
x
.
26. If
x
+ 10 = 2, find
x
.
27. If
x
– 2 = –5, find
x
.
28. If
x
+ 4 = –8, find
x
.
29. If
x
– 10 = –14, find
x
.
30. If .5
x
– 1 = –6, find
x
.
L1675_C34.fm Page 350 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
Workbook Practice Problems
351
31. If 9
x
+ 1 = 0, find
x
.
32. How much is
x
2
if
x
= 6?
33. If
x
= 3, find
x
4
.
34. If
x
= 10, find
x
0
.
R
ATIO
AND
P
ROPORTION
35. If an employee was out sick for 6 of 96 workdays, what is the ratio of sick days to days
worked?
36. Find
x
when 2:
x
= 5:15.
A
REA
OF
R
ECTANGLES
37. What is the area of the rectangle shown in Figure 34.1?
3 feet
3 feet
Figure 34.1
L1675_C34.fm Page 351 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
352
Mathematics for Water/Wastewater Treatment Plant Operators
38. What is the area of the rectangle shown in Figure 34.2?
39. What is the area of the rectangle shown in Figure 34.3?
C
IRCUMFERENCE
AND
A
REA
OF
C
IRCLES
40. Find the circumference of a circle with diameter of 14 ft.
41. If the circumference of a circle is 8 inches, what is the diameter?
42. If the radius of a circle is 7 inches, what is the area?
43. If the diameter of a circle is 10 inches, what is the area?
Figure 34.2
5 inches
3 inches
1 yard
5 yards
Figure 34.3
L1675_C34.fm Page 352 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
Workbook Practice Problems
353
FUNDAMENTAL OPERATIONS (WATER/WASTEWATER)
(PROBLEMS 1 TO 342)
T
ANK
V
OLUME
C
ALCULATIONS
1. The diameter of a tank is 70 ft. If the water depth is 25 ft, what is the volume of water in
the tank (in gallons)?
2. A tank is 60 ft in length, 20 ft wide, and 10 ft deep. Calculate the cubic foot volume of the
tank.
3. A tank 20 ft wide and 60 ft long is filled with water to a depth of 12 ft. What is the volume
of the water in the tank (in gal)?
4. What is the volume of water in a tank (in gallons) if the tank is 20 ft wide by 40 ft long
and contains water to a depth of 12 ft?
5. A tank has a diameter of 60 ft and a depth of 12 ft. Calculate the volume of water in the
tank (in gallons).
6. What is the volume of water in a tank (in gallons) if the tank is 20 ft wide by 50 ft long
and contains water to a depth of 16 ft?
C
HANNEL
AND
P
IPELINE
C
APACITY
C
ALCULATIONS
7. A rectangular channel is 340 ft long, 4 ft deep, and 6 ft wide. What is the volume of water
(in cubic feet)?
L1675_C34.fm Page 353 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
354
Mathematics for Water/Wastewater Treatment Plant Operators
8. A replacement section of 10-inch pipe is to be sandblasted before it is put into service. If
the length of pipeline is 1600 ft, how many gallons of water will be needed to fill the
pipeline?
9. A trapezoidal channel is 800 ft long, 10 ft wide at the top, and 5 ft wide at the bottom,
with a distance of 4 ft from the top edge to bottom along the sides. Calculate the gallon
volume.
10. A section of 8-inch diameter pipeline is to be filled with treated water for distribution. If
the pipeline is 2250 ft in length, how many gallons of water will be distributed?
11. A channel is 1200 ft in length, carries water 4 ft deep, and is 5 ft wide. What is the volume
of water (in gallons)?
M
ISCELLANEOUS
V
OLUME
C
ALCULATIONS
12. A pipe trench is to be excavated that is 4 ft wide, 4 ft deep, and 1200 ft long. What is the
volume of the trench (in cubic yards)?
13. A trench is to be excavated that is 3 ft wide, 4 ft deep, and 500 yds long. What is the cubic
yard volume of the trench?
14. A trench is 300 yards long, 3 ft wide, and 3 ft deep. What is the volume of the trench (in
cubic feet)?
L1675_C34.fm Page 354 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
Workbook Practice Problems
355
15. A rectangular trench is 700 ft long, 6.5 ft wide, and 3.5 ft deep. What is the volume of the
trench (in cubic feet)?
16. The diameter of a tank is 90 ft. If the water depth in the tank is 25 ft, what is the volume
of water in the tank (in gallons)?
17. A tank is 80 ft long, 20 ft wide, and 16 ft deep. What is the volume of the tank (in cubic feet)?
18. How many gallons of water are required to fill an 8-inch-diameter pipe that is 4000 ft in
length?
19. A trench is 400 yards long, 3 ft wide, and 3 ft deep. What is the volume of the trench (in
cubic feet)?
20. A trench is to be excavated. If the trench is 3 ft wide, 4 ft deep, and 1200 ft long, what is
the volume of the trench (in cubic yards)?
21. A tank is 30 ft wide and 80 ft long. If the tank contains water to a depth of 12 ft, how many
gallons of water are in the tank?
22. What is the volume of water (in gallons) contained in a 3000-ft section of channel if the
channel is 8 ft wide and the water depth is 3.5 ft?
L1675_C34.fm Page 355 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
356
Mathematics for Water/Wastewater Treatment Plant Operators
23. A tank has a diameter of 70 ft and a depth of 19 ft. What is the volume of water in the tank
(in gallons)?
24. If a tank is 25 ft in diameter and 30 ft deep, how many gallons of water will it hold?
F
LOW
, V
ELOCITY
,
AND
C
ONVERSION
C
ALCULATIONS
25. A channel 44 inches wide has water flowing to a depth of 2.4 ft. If the velocity of the water
is 2.5 fps, what is the flow in the channel (in cfm)?
26. A tank is 20 ft long and 12 ft wide. With the discharge valve closed, the influent to the tank
causes the water level to rise 0.8 ft in 1 minute. What is the flow to the tank (in gpm)?
27. A trapezoidal channel is 4 ft wide at the bottom and 6 ft wide at the water surface. The
water depth is 40 inches. If the flow velocity through the channel is 130 ft/min, what is the
flow rate through the channel (in cfm)?
28. An 8-inch diameter pipeline has water flowing at a velocity of 2.4 fps. What is the flow
rate through the pipeline (in gpm)? Assume the pipe is flowing full.
29. A pump discharges into a 3-ft-diameter container. If the water level in the container rises
28 inches in 30 seconds, what is the flow into the container (in gpm)?
L1675_C34.fm Page 356 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
Workbook Practice Problems
357
30. A 10-inch-diameter pipeline has water flowing at a velocity of 3.1 fps. What is the flow
rate through the pipeline if the water is flowing at a depth of 5 inches (in gpm)?
31. A channel has a rectangular cross section. The channel is 6 ft wide, and water flows to a
depth of 2.6 ft. If the flow rate through the channel is 14,200 gpm, what is the velocity of
the water in the channel (in ft/sec)?
32. An 8-inch diameter pipe flowing full delivers 584 gpm. What is the velocity of flow in the
pipeline (in ft/sec)?
33. A special dye is used to estimate the velocity of flow in an interceptor line. The dye is
injected into the water at one pumping station, and the travel time to the first manhole 550 ft
away is noted. The dye first appears at the downstream manhole in 195 seconds. The dye
continues to be visible until the total elapsed time is 221 seconds. What is the velocity of
flow through the pipeline (in ft/sec)?
34. The velocity in a 10-inch-diameter pipeline is 2.4 ft/sec. If the 10-inch pipeline flows into
an 18-inch-diameter pipeline, what is the velocity in the 8-inch pipeline (in ft/sec)?
35. A float travels 500 ft in a channel in 1 minute 32 sec. What is the estimated velocity in the
channel (in ft/sec)?
36. The velocity in an 8-inch-diameter pipe is 3.2 ft/sec. If the flow then travels through a 10-
inch diameter section of pipeline, what is the velocity in the 10-inch pipeline (in ft/sec)?
L1675_C34.fm Page 357 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
358
Mathematics for Water/Wastewater Treatment Plant Operators
A
VERAGE
F
LOW
R
ATES
37. The following flows were recorded for the week: Monday, 4.8 MGD; Tuesday, 5.1 MGD;
Wednesday, 5.2 MGD; Thursday, 5.4 MGD; Friday, 4.8 MGD; Saturday, 5.2 MGD; Sunday,
4.8 MGD. What was the average daily flow rate for the week?
38. The total reading for the month of September was 121.4 MG. What was the average daily
flow (ADF) for the month of September?
F
LOW
C
ONVERSIONS
39. Convert 0.165 MGD to gpm.
40. The total flow for 1 day at a plant was 3,335,000 gallons. What was the average gpm flow
for that day?
41. Express a flow of 8 cfs in terms of gpm.
42. What is 35 gps expressed as gpd?
43. Convert a flow of 4,570,000 gpd to cfm.
44. What is 6.6 MGD expressed as cfs?
L1675_C34.fm Page 358 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
Workbook Practice Problems
359
45. Express 445,875 cfd as gpm.
46. Convert 2450 gpm to gpd.
G
ENERAL
F
LOW
AND
V
ELOCITY
C
ALCULATIONS
47. A channel has a rectangular cross section. The channel is 6 ft wide with water flowing to
a depth of 2.5 ft. If the flow rate through the channel is 14,800 gpm, what is the velocity
of the water in the channel (in ft/sec)?
48. A channel 55 inches wide has water flowing to a depth of 3.4 ft. If the velocity of the water
is 3.6 fps, what is the flow in the channel in cfm?
49. The following flows were recorded for 3 months: June, 102.4 MG; July, 126.8 MG; August,
144.4 MG. What was the average daily flow for this 3-month period?
50. A tank is 12 ft by 12 ft. With the discharge valve closed, the influent to the tank causes the
water level to rise 8 inches in 1 minute. What is the rate of flow to the tank (in gpm)?
51. An 8-inch diameter pipe flowing full delivers 510 gpm. What is the velocity of flow in the
pipeline (in ft/sec)?
52. Express a flow of 10 cfs in terms of gpm.
L1675_C34.fm Page 359 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
360
Mathematics for Water/Wastewater Treatment Plant Operators
53. The total reading for the month of December was 134.6 MG. What was the average daily
flow (ADF) for the month of September?
54. What is 5.2 MGD expressed as cfs?
55. A pump discharges into a 3-ft-diameter container. If the water level in the container rises
20 inches in 30 seconds, what is the rate of flow into the container (in gpm)?
56. Convert a flow of 1,825,000 gpd to cfm.
57. A 6-inch diameter pipeline has water flowing at a velocity of 2.9 fps) What is the flow rate
through the pipeline (in gpm)?
58. The velocity in a 10-inch pipeline is 2.6 ft/sec. If the 10-inch pipeline flows into an 8-inch
diameter pipeline, what is the velocity in the 8-inch pipeline (in feet per second)?
59. Convert 2225 gpm to gpd.
60. The total flow for 1 day at a plant was 5,350,000 gallons. What was the average gpm flow
for that day?
L1675_C34.fm Page 360 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
Workbook Practice Problems
361
C
HEMICAL
D
OSAGE
C
ALCULATIONS
61. Determine the chlorinator setting (lb/day) required to treat a flow of 5.5 MGD with a chlorine
dose of 2.5 mg/L.
62. To dechlorinate a wastewater, sulfur dioxide is to be applied at a level 4 mg/L more than
the chlorine residual. What should the sulfonator feed rate be (in lb/day) for a flow of 4.2
MGD with a chlorine residual of 3.1 mg/L?
63. What should the chlorinator setting be (in lb/day) to treat a flow of 4.8 MGD if the chlorine
demand is 8.8 mg/L and a chlorine residual of 3 mg/L is desired?
64. A total chlorine dosage of 10 mg/L is required to treat the water in a unit process. If the
flow is 1.8 MGD and the hypochlorite has 65% available chlorine, how many lb/day of
hypochlorite will be required?
65. The chlorine dosage at a plant is 5.2 mg/L. If the flow rate is 6,250,000 gpd, what is the
chlorine feed rate (in lb/day)?
66. A storage tank is to be disinfected with 60 mg/L of chlorine. If the tank holds 86,000
gallons, how many lb of chlorine (gas) will be needed?
67. To neutralize a sour digester, one lb of lime is to be added for every lb of volatile acids in
the digester liquor. If the digester contains 225,000 gal of sludge with a volatile acid (VA)
level of 2220 mg/L, how many lb of lime should be added?
L1675_C34.fm Page 361 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
362
Mathematics for Water/Wastewater Treatment Plant Operators
68. A flow of 0.83 MGD requires a chlorine dosage of 8 mg/L. If the hypochlorite has 65%
available chlorine, how many lb/day of hypochlorite will be required?
BOD, COD,
AND
SS L
OADING
C
ALCULATIONS
69. The suspended solids concentration of wastewater entering a primary system is 450 mg/L.
If the plant flow is 1,840,000 gpd, how many lb/day suspended solids enter the primary
system?
70. Calculate the BOD loading (lb/day) on a stream if the secondary effluent flow is 2.90 MGD
and the BOD of the secondary effluent is 25 mg/L.
71. The daily flow to a trickling filter is 5,450,000 gpd. If the BOD content of the trickling
filter influent is 260 mg/L, how many lb/day BOD enter the trickling filter?
72. The flow to an aeration tank is 2540 gpm. If the COD concentration of the water is 144
mg/L, how many lb of COD are applied to the aeration tank daily?
73. The daily flow to a trickling filter is 2300 gpm with a BOD concentration of 290 mg/L.
How many lb of BOD are applied to the trickling filter daily?
BOD
AND
SS R
EMOVAL
(lb/day)
74. If a primary clarifier removes 152 mg/L suspended solids, how many lb/day suspended
solids are removed when the flow is 5.7 MGD?
L1675_C34.fm Page 362 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
Workbook Practice Problems
363
75. The flow to a primary clarifier is 1.92 MGD. If the influent to the clarifier has a suspended
solids concentration of 310 mg/L and the primary effluent has 122 mg/L SS, how many lb/day
suspended solids are removed by the clarifier?
76. The flow to a primary clarifier is 1.88 MGD. If the influent to the clarifier has a suspended
solids concentration of 305 mg/L and the primary effluent has 121 mg/L SS, how many
lb/day suspended solids are removed by the clarifier?
77. The flow to a trickling filter is 4,880,000 gpd. If the primary effluent has a BOD concen-
tration of 150 mg/L and the trickling filter effluent has a BOD concentration of 25 mg/L,
how many lb of BOD are removed daily?
78. A primary clarifier receives a flow of 2.13 MGD with a suspended solids concentration of
367 mg/L. If the clarifier effluent has a suspended solids concentration of 162 mg/L, how
many lb of suspended solids are removed daily?
79. The flow to the trickling filter is 4,200,000 gpd with a BOD concentration of 210 mg/L. If
the trickling filter effluent has a BOD concentration of 95 mg/L, how many lb/day BOD
does the trickling filter remove?
P
OUNDS
OF
S
OLIDS
U
NDER
A
ERATION
80. The aeration tank has a volume of 400,000 gallons. If the mixed liquor suspended solids
concentration is 2230 mg/L, how many lb of suspended solids are in the aerator?
L1675_C34.fm Page 363 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
364
Mathematics for Water/Wastewater Treatment Plant Operators
81. The aeration tank of a conventional activated sludge plant has a mixed liquor volatile
suspended solids concentration of 1890 mg/L. If the aeration tank is 115 ft long by 40 ft
wide and has wastewater to a depth of 12 ft, how many lb of MLVSS are under aeration?
82. The volume of an oxidation ditch is 23,800 cubic feet. If the MLVSS concentration is 3125
mg/L, how many lb of volatile solids are under aeration?
83. An aeration tank is 110 ft long and 40 ft wide. The operating depth is 16 ft. If the mixed
liquor suspended solids concentration is 2250 mg/L, how many lb of mixed liquor suspended
solids are under aeration?
84. An aeration tank is 105 ft long and 50 ft wide. The depth of wastewater in the tank is 16 ft.
If the tank contains an MLSS concentration of 2910 mg/L, how many lb of MLSS are under
aeration?
WAS P
UMPING
R
ATE
C
ALCULATIONS
85. The WAS suspended solids concentration is 6150 mg/L. If 5200 lb/day solids are to be
wasted, what must the WAS pumping rate be (in MGD)?
86. The WAS suspended solids concentration is 6200 mg/L. Assume that 4500 lb/day solids
are to be wasted. (a) What must the WAS pumping rate be (in MGD)? (b) What is this rate
expressed in gpm?
87. It has been determined that 6070 lb/day of solids must be removed from a secondary system.
If the RAS suspended solids concentration is 6600 mg/L, what must be the WAS pumping
rate (in gpm)?
L1675_C34.fm Page 364 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
Workbook Practice Problems
365
88. The RAS suspended solids concentration is 6350 mg/L. If 7350 lb/day solids are to be
wasted, what should the WAS pumping rate be (in gpm)?
89. A total of 5750 lb/day of solids must be removed from a secondary system. If the RAS
suspended solids concentration is 7240 mg/L, what must be the WAS pumping rate (in gpm)?
90. Determine the chlorinator setting (lb/day) required to treat a flow of 3,650,000 gpd with a
chlorine dose of 2.5 mg/L.
91. Calculate the BOD loading (lb/day) on a stream if the secondary effluent flow is 2.10 MGD
and the BOD of the secondary effluent is 17 mg/L.
92. The flow to a primary clarifier is 4.8 MGD. If the influent to the clarifier has a suspended
solids concentration of 310 mg/L and the primary effluent suspended solids concentration
is 120 mg/L, how many lb/day suspended solids are removed by the clarifier?
93. What should the chlorinator setting be (lb/day) to treat a flow of 5.5 MGD if the chlorine
demand is 7.7 mg/L and a chlorine residual of 2 mg/L is desired?
94. The suspended solids concentration of the wastewater entering primary system is 305 mg/L.
If the plant flow is 3.5 MGD, how many lb/day suspended solids enter the primary system?
L1675_C34.fm Page 365 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
366
Mathematics for Water/Wastewater Treatment Plant Operators
95. A total chlorine dosage of 10 mg/L is required to treat water in a unit process. If the flow
is 3.1 MGD and the hypochlorite has 65% available chlorine, how many lb/day of hypochlo-
rite will be required?
96. A primary clarifier receives a flow of 3.44 MGD with a suspended solids concentration of
350 mg/L. If the clarifier effluent has a suspended solids concentration of 140 mg/L, how
many lb of suspended solids are removed daily?
97. A storage tank is to be disinfected with 60 mg/L of chlorine. If the tank holds 90,000
gallons, how many lb of chlorine gas will be needed?
98. An aeration tank is 110 ft long by 45 ft wide. The operating depth is 14 ft. If the mixed
liquor suspended solids concentration is 2720 mg/L, how many lb of mixed liquor suspended
solids are under aeration?
99. The WAS suspended solids concentration is 5870 mg/L. If 5480 lb/day solids are to be
wasted, what must the WAS pumping rate be (in MGD)?
100. The flow to an aeration tank is 2300 gpm. If the COD concentration of the water is 120 mg/L,
how many lb COD enter the aeration tank daily?
101. The daily flow to a trickling filter is 2210 gpm. If the BOD concentration of the trickling
filter influent is 240 mg/L, how many lb/day BOD are applied to the trickling filter?
L1675_C34.fm Page 366 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
Workbook Practice Problems
367
102. The 1.7-MGD influent to the secondary system has a BOD concentration of 220 mg/L. The
secondary effluent contains 24 mg/L BOD. How many lb of BOD are removed each day
by the secondary system?
103. The chlorine feed rate at a plant is 330 lb/day. If the flow is 5,300,000 gpd, what is this
dosage expressed in mg/L?
104. It has been determined that 6150 lb/day solids must be removed from a secondary system.
If the RAS SS concentration is 5810 mg/L, what must be the WAS pumping rate (in gpm)?
H
YDRAULIC
L
OADING
R
ATE
C
ALCULATIONS
105. A trickling filter 100 ft in diameter treats a primary effluent flow of 2.5 MGD. If the
recirculated flow to the clarifier is 0.9 MGD, what is the hydraulic loading on the trickling
(in gpd/sq ft)?
106. The flow to a 90-ft-diameter trickling filter is 2,850,000 gpd. The recirculated flow is
1,675,000 gpd. At this flow rate, what is the hydraulic loading rate (in gpd/sq ft)?
107. A rotating biological contactor treats a flow of 3.8 MGD. Information provided by the
manufacturer indicates a media surface area of 870,000 sq ft. What is the hydraulic loading
rate on the RBC (in gpd/sq ft)?
108. A pond receives a flow of 2,100,000 gpd. If the surface area of the pond is 16 acres, what
is the hydraulic loading (in in./day)?
L1675_C34.fm Page 367 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
368
Mathematics for Water/Wastewater Treatment Plant Operators
109. What is the hydraulic loading rate (in gpd/sq ft) to a 90-ft-diameter trickling filter if the
primary effluent flow to the tickling filter is 3,880,000 gpd and the recirculated flow is
1,400,000 gpd?
110. A 20-acre pond receives a flow of 4.4 acre-feet/day. What is the hydraulic loading on the
pond (in in./day)?
S
URFACE
O
VERFLOW
R
ATE
C
ALCULATIONS
111. A sedimentation tank 70 ft by 25 ft receives a flow of 2.05 MGD. What is the surface
overflow rate (in gpd/sq ft)?
112. A circular clarifier has a diameter of 60 ft. If the primary effluent flow is 2.44 MGD, what
is the surface overflow rate (in gpd/sq ft)?
113. A sedimentation tank is 110 ft long and 50 ft wide. If the flow to the tank is 3.45 MGD
what is the surface overflow rate (in gpd/sq ft)?
114. The primary effluent flow to a clarifier is 1.66 MGD. If the sedimentation tank is 25 ft wide
by 70 ft long, what is the surface overflow rate of the clarifier (in gpd/sq ft)?
115. The flow to a circular clarifier is 2.66 MGD. If the diameter of the clarifier is 70 ft, what
is the surface overflow rate (in gpd/sq ft)?
L1675_C34.fm Page 368 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
Workbook Practice Problems
369
F
ILTRATION
R
ATE
C
ALCULATIONS
116. A filter 40 ft by 20 ft receives a flow of 2230 gpm. What is the filtration rate (in gpm/sq ft)?
117. A filter 40 ft by 25 ft receives a flow of 3100 gpm. What is the filtration rate (in gpm/sq ft)?
118. A filter 26 ft by 60 ft receives a flow of 2500 gpm. What is the filtration rate (in gpm/sq ft)?
119. A filter 40 ft by 20 ft treats a flow of 2.2 MGD. What is the filtration rate (in gpm/sq ft)?
120. A filter has a surface area of 880 sq ft. If the flow treated is 2850 gpm, what is the filtration
rate (in gpm/sq ft)?
B
ACKWASH
R
ATE
C
ALCULATIONS
121. A filter 14 ft by 14 ft has a backwash flow rate of 4750 gpm. What is the filter backwash
rate (in gpm/sq ft)?
122. A filter 20 ft by 20 ft has a backwash flow rate of 4900 gpm. What is the filter backwash
rate (in gpm/sq ft)?
123. A filter is 25 ft by 15 ft. If the backwash flow rate is 3400 gpm, what is the filter backwash
rate (in gpm/sq ft)?
L1675_C34.fm Page 369 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
370
Mathematics for Water/Wastewater Treatment Plant Operators
124. A filter 25 ft by 30 ft backwashes at a rate of 3300 gpm. What is this backwash rate expressed
as gpm/sq ft?
125. The backwash flow rate for a filter is 3700 gpm. If the filter is 15 ft by 20 ft, what is the
backwash rate expressed as gpm/ft?
U
NIT
F
ILTER
R
UN
V
OLUME
(UFRV) C
ALCULATIONS
126. The total water filtered during a filter run is 3,770,000 gallons. If the filter is 15 ft by 30 ft,
what is the unit filter run volume (UFRV) (in gal/sq ft)?
127. The total water filtered during a filter run (between backwashes) is 1,860,000 gallons. If
the filter is 20 ft by 15 ft, what is the unit filter run volume (UFRV) (in gal/sq ft)?
128. A filter 25 ft by 20 ft filters a total of 3.88 MG during a filter run. What is the unit filter
run volume (in gal/sq ft)?
129. The total water filtered between backwashes is 1,410,200 gal. If the filter is 20 ft long and
14 ft wide, what is the unit filter run volume (in gal/sq ft)?
130. A filter is 30 ft by 20 ft. If the total water filtered between backwashes is 5,425,000 gallons,
what is the UFRV (in gal/sq ft)?
L1675_C34.fm Page 370 Saturday, January 31, 2004 6:09 PM
© 2004 by CRC Press LLC
