The document is a final exam for an environmental studies course (ENV 3001) dated June 18, 2015, consisting of multiple-choice questions covering waste management, water quality analysis, and related calculations. Students are required to fill in their answers and transfer them to an answer sheet, addressing topics such as biochemical oxygen demand (BOD), solid waste generation, and water characteristics. Specific questions involve dilution factors, concentrations, and chemical compositions related to environmental engineering principles.

1. ENV 3001 Final Exam_Summer 2015.pdf
ENV 3001 Name:___________________
Final Exam Date: June 18, 2015
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Answer all questions in the space provided and transfer your
answers to the answer sheet.
1-2. The dilution factor P of an unseeded mixture of liquid
wastewater is 0.03. The initial DO of the
mixture is 10.0 mg/L. After 5 days, DO has dropped to 1.0
mg/L.
Assuming: Reaction rate constant k = 0.22 day
-1
.

4. 1. The 5-day BOD of the waste is most nearly:
a. 600 mg/L
b. 500 mg/L
c. 400 mg/L
d. 300 mg/L
e. 200 mg/L
f. other, write your answer _________________
2. The ultimate BOD of the liquid waste would be most nearly:
a. 550 mg/L
b. 450 mg/L
c. 350 mg/L
d. 240 mg/L
e. 150 mg/L
f. other, write your answer _________________
3-4. A water sample has the following analysis:
Concentration (mg/L) Atomic/ionic weight
Ca
+2

5. 80 40
Mg
+2
30 24.4
Na
+
72 23
K
+
6 39
Cl
-
100 35.5
SO4
-2
201 96
HCO3
-
162 61
3. Total hardness of the water is most nearly (as mg/L as
CaCO3):
a. 479 mg/L
b. 344 mg/L

6. c. 323 mg/L
d. 200 mg/L
e. 135 mg/L
f. other, write your answer _________________
4. Total carbonate harness is most nearly (as mg/L as CaCO3):
a. 479 mg/L
b. 441 mg/L
c. 323 mg/L
d. 266 mg/L
e. 133 mg/L
f. other, write your answer _________________
5. NO2 concentration in air is measures as 0.25 ppm at 25
o
C and 1 atm pressure. The concentration

7. of NO2 in µg/m
3
is most nearly:
Atomic weights: N: 14 O: 16
a. 770
b. 640
c. 520
d. 470
e. 320
f. other, write your answer _________________
6-8. A rural community of 20,000 persons generates solid waste
at an average rate of 7 lbs
per person per day. A 20-acre landfill site (fill area) is
available. The average depth of fill is
limited to 40 ft.
Assume:
Compacted density of refuse : 1,200 lb/yd
3
Uncompacted density of refuse : 300 lb/yd

8. 3
Cover-to-waste ratio: 1 to 4
1 acre = 43,560 ft
2
1 yard = 3 ft
6. Compaction ratio of the waste is:
a. 4
b. 3
c. 2
d. 1
e. 0.33
f. other, write your answer _________________
7. Air space available is (assume the landfill will be a pyramid
with height of 40 ft)
(area of pyramid = base are x height/3)
a. 5.33 million cubic yards
b. 3.24 million cubic yards

9. c. 2.12 million cubic yards
d. 1.35 million cubic yards
e. 0.43 million cubic yards
f. other, write your answer _________________
8. Estimated useful life of the landfill (in years) is:
a. 24
b. 12
c. 8
d. 6
e. 4
f. other, write your answer _________________
9-10. A liquid waste has the following composition:
C : 84%
H : 15.6%
N : 0.4 % (assume N does not burn)
Atomic weights: C: 12 H: 1 O:12 N:14

10. 9. How much oxygen is needed to burn 1 Kg of waste this
waste:
a. 17.5 Kg
b. 15.0 Kg
c. 7.0 Kg
d. 5.0 Kg
e. 3.5 Kg
f. other, write your answer _________________
10. How much air is needed to burn 1 Kg of this waste with
20% excess air:
Assume air is 23% oxygen (w/w)
a. 18.3 Kg
b. 15.1 Kg
c. 7.5 Kg
d. 5.6 Kg
e. 3.5 Kg
f. other, write your answer _________________

11. 11-14. The concentration of a solution is given as: 0.03 N
Al2(SO4) 3
Atomic weights: Al: 27, S : 32, Ca: 40, C : 12,
O : 16
11. This solution is:
a 0.030 M
b 0.020 M
c 0.015 M
d 0.010 M
e 0.005 M
f other, write your answer _________________
12. The concentration of Al2(SO4) 3 in the solution above is in
mg/L (most nearly):
a 10,126 mg/L
b 6,840 mg/L
c 10,260 mg/L
d 5,130 mg/L
e 1,710 mg/L

12. f other, write your answer _________________
13. The solution above in % is most nearly:
a 1.01
b 0.685
c 1.51
d 0.34
e 0.17
f other, write your answer _________________
14. The solution above in mg/L as CaCO3 is most nearly:
a 1,500
b 1,000
c 1.5
d 1
e 0.5
f other, write your answer _________________

13. 15. The primary sludge from a wastewater treatment plant is
produced at a rate of 1,200 gals/day at a
solid concentration of 4%. The amount of solids in lbs/day is
(most nearly):
a. 40 lbs/day
b. 400 lbs/day
c. 4,000 lbs/day
d. 40,000 lbs/day
e. 400,000 lbs/day
f. other, write your answer _________________
16. The circular settling tank has a surface area of 10,000 ft
2
and has a depth of 10 ft.
If the overflow rate is 60 ft/d, detention time (hours) is most
nearly:
a. 2 hours
b. 4 hours
c. 6 hours
d. 10 hours
e. 24 hours

14. f. other, write your answer _________________
Q17-18. Two moles of propane (C3H8) gas is burned with 40%
excess air.
Molecular weights: C: 12 H: 1 O: 16 N: 14
17. The % of CO2 in the flue gas on wet basis is most nearly
(v/v):
a. 5%
b. 10%
c. 15%
d. 20%
e. 25%
f. other (write your answer) _____________
18. Volume of propane burned at STP is most nearly:
a. 10.4 L
b. 44.8 L

15. c. 22.4 L
d. 50.2 L
e. 56.2 L
f. other (write your answer) _____________
19. If the solids concentration in a primary sludge is 5% and the
sludge flow is 2 MGD, the amount
solids in the sludge is most nearly:
a. 20 lbs/day
b. 200 lbs/day
c. 2,000 lbs/day
d. 20,000 lbs/day
e. 200,000 lbs/day
f. other (write your answer) _____________
20. The volume of a sedimentation tank receiving 4 MGD
influent with a detention time of 1 hour is

16. most nearly:
a. 40 gallons
b. 96 gallons
c. 4,000,000 gallons
d. 96,000,000 gallons
e. 40,000,000 gallons
f. other (write your answer) _____________
21. If the solids concentration in the primary sludge is 5%, the
solids concentration in mg/L is:
a. 0.05 mg/L
b. 0.5 mg/L
c. 5 mg/L
d. 5,000 mg/L
e. 50,000 mg/L
f. other, write your answer _________________
22. PM10 particles in air
a. Are greater than 10 nanometers in diameter
b. Are less than 10 nanometers in diameter

17. c. Are between 2.5 and 10 nanometers in diameter
d. Are greater than 10 microns in diameter
e. Have an average diameter of 10 microns in diameter
f. Are less than 10 microns in diameter
23. The flow to a primary clarifier is 2 MGD. If the SS
concentration of the influent and
effluent are 300 mg/L and 120 mg/L, respectively; the solids
removed (lbs/day) is most
nearly:
a. 300
b. 500
c. 1,000
d. 2,000
e. 3,000
f. other (provide your answer) _________
24. Overflow rate in primary tank primary clarifier (L= 100 ft,
W= 20 ft, D= 10 ft) is 1,500
gpd/ft
2

18. . Settling velocity (ft/min) is most nearly: (7.48 gallons = 1 ft
3
)
a. 0.10
b. 0.14
c. 0.18
d. 0.20
e. 0.24
f. other (provide your answer) _________
25-27. An activated sludge process has the following
conditions:
Q= 15 MGD
SS = 150 mg/L
BOD = 200 mg/L
R
WAS
Volume= 1 MG
MLSS= 3500 mg/L
Q= 15 MGD
SS = 2 mg/L

19. BOD = 2 mg/L
Yield coefficient: 0.5 lbs /lb of BOD
R/Q = 1/3
25. Mass of dry solids produced (lbs/day) by the activated
sludge process (in WAS) is most
nearly:
a. 1250
b. 12,385
c. 18,765
d. 29,190
e. 437,850
f. other (write your answer) _____________
26. If waste activated sludge (WAS) contains 15,000 lbs/day
solids at 1% concentration, the
flow rate of the waste activated sludge is most nearly (gpd) ?
a. 15,000
b. 150,000
c. 180,000
d. 1,500,000

20. e. 1,800,000
f. other (write your answer) _____________
27. If the solids concentration is to be increased from 1% to 6%
by a thickener, the volume
reduction by the thickener (%) is most nearly?
(assume sludge has similar density as water)
a. 17
b. 33
c. 50
d. 75
e. 83
f. other (write your answer) _____________
28. 50 m

21. 3
/day sludge is thickened from 1% to 5% according to the
following schematic. The
flow rate of thickened sludge (stream 2 below) is most nearly:
Q=50 m3/day
SS= 1%
SS= 0%
SS= 5%
Q=50 m3/day
SS= 1%
1
2
3
a 40 m
3
/day
b 30 m
3
/day
c 25 m
3
/day

22. d 20 m
3
/day
e 10 m
3
/day
e other, write your answer _________________
29-31. Referring to the following bar graph of ionic
constituents, where the concentrations are
expressed as mg/L as CaCO3:
Ca+2 Mg+2 Na+
HCO3
- SO4
-2 Cl2
0 120 260
370
0 150
310
29. Total hardness is (as mg/L as CaCO3):
a 370

23. b 310
c 260
d 150
e 120
e other, write your answer _________________
30. Referring to the above figure, total carbonate hardness is (as
mg/L as CaCO3):
a 370
b 310
c 260
d 150
e 120
e other, write your answer _________________
31. Referring to the above figure, total noncarbonate hardness is
(as mg/L as CaCO3):

24. a 310
b 260
c 150
d 120
e 110
e other, write your answer _________________
32. 6 MGD of wastewater with a dissolved oxygen
concentration of 0.9 mg/L is discharged to a
river flowing at 40 ft
3
/sec. The river initially is saturated with oxygen. The
saturation DO
is 11.30 mg/L. The oxygen content of the river (mg/L)
immediately after mixing is most
nearly: (conversion factor: 7.48 gal= 1 ft
3
)
a 11.30
b 9. 34
c 9.00
d 8.85

25. e 7.24
e other, write your answer _________________
33-35. For the following oxygen sag curve:
0 5 10 15 20 25
10
8
6
4
2
0
D
O
(
m
g/
L)
Time (mg/L)
33. Initial DO deficit is most nearly

26. a 9 mg/L
b 6 mg/L
c 3 mg/L
d 1 mg/L
e 0 mg/L
e other, write your answer _________________
34. Referring to the figure above, critical deficit is most nearly
a 9 mg/L
b 8 mg/L
c 6 mg/L
d 3 mg/L
e 1 mg/L
e other, write your answer _________________
35. Referring to the figure above, after 20 days, DO deficit is
most nearly
a 9 mg/L

27. b 6 mg/L
c 3 mg/L
d 1 mg/L
e about 0.05 mg/L (nearly zero)
e other, write your answer _________________
__MACOSX/._ENV 3001 Final Exam_Summer 2015.pdf
ENV 3001 Formula sheet.pdf
__MACOSX/._ENV 3001 Formula sheet.pdf