Civil Engineering - Waste Water Engineering MCQs Part 6
1. To maintain aerobic biological activity, the moisture content of the compost mass should be about
A.
45%
45%
B.
50%
50%
C.
55%
55%
D.
60%.
60%.
Answer Option C
2. The sewer that unloads the sewage at the point of treatment is called
A.
main sewer
main sewer
B.
outfall sewer
outfall sewer
C.
branch sewer
branch sewer
D.
house sewer.
house sewer.
Answer Option B
3. No treatment of the sewage is given if dilution factor is
A.
less than 150
less than 150
B.
between 150 to 200
between 150 to 200
C.
between 200 to 300
between 200 to 300
D.
between 400 to 500
between 400 to 500
E.
more than 500
more than 500
Answer Option E
4. R.M.O. expenses include
A.
running expenses
running expenses
B.
maintenance expenses
maintenance expenses
C.
operation expenses
operation expenses
D.
all the above.
all the above.
Answer Option D
5. For drainage pipes in buildings the test applied before putting them to use, is
A.
water test
water test
B.
smoke test
smoke test
C.
straightness test
straightness test
D.
all the above.
all the above.
Answer Option B
6. In normal conditions, the period for sludge digestion, is
A. 10 days
B. 20 days
C. 30 days
D. 60 days
E. 90 days.
Answer Option C
7. The bottom of the sewage inlet chamber of septic tanks, is provided an outward slope
A. 1 in 5
B. 1 in 10
C. 1 in 15
D. 1 in 20
E. 1 in 25
Answer Option B
8. For a continuous flow type of sedimentation tanks
A. width of the tank is normally kept about 6 m
B. length of the tank is normally kept 4 to 5 times the width
C. maximum horizontal flow velocity is limited to 0.3 m/minute
D. capacity of the tank for 24 hours, is kept equal to maximum daily flow of sewage
E. all the above.
Answer Option E
9. The temperature affects the
A. biological activity of bacterias in sewage
B. solubility of gases in sewage
C. viscosity of sewage
D. all the above.
Answer Option D
10. Which of the following pumps in used to pump sewage solids with liquid sewage without clogging the pump is
A. centrifugal pump
B. pneumatic ejector
C. reciprocating pump
D. none of these.
Answer Option A
11. For having central angle α, the area of cross-section of sewers running partially full, is
A.
B.
C.
D.
Answer Option B
12. The pressure exerted by
A. the sewage when running full from inside, is called internal pressure
B. the internal pressure if any, causes tensile stress in the pipe material
C. pressure sewers are designed to be safe in tension
D. All the above.
Answer Option D
13. A cylindrical ejector having its height 2 m fills after every 10 minutes with a peak sewage discharge of 0.0157 cumec. The diameter of the ejector chamber, is
A. 2.30 m
B. 2.40 m
C. 2.45 m
D. 2.50 m.
Answer Option C
14. The flow velocity in detritus tanks is
A. 0.05 m/sec
B. 0.09 m/sec
C. 1.25 m/sec
D. none of these.
Answer Option B
15. The following is the physical characteristic of sewage
A. turbidity
B. colour
C. odour
D. temperature
E. all the above.
Answer Option E
16. The normal value of over flow rates for plain primary sedimentation tanks, ranges between
A. 25, 000 to 35, 000 litres/sqm/day
B. 40, 000 to 50, 000 litres/sqm/day
C. 50, 000 to 60, 000 litres/sqm/day
D. 80, 000 to 100, 000 litres/sqm/day
E. none of these.
Answer Option B
17. The asbestos cement sewers are
A. light in weight
B. not structurally strong to bear large compressive stress
C. susceptible to corrosion by sulphuric acid
D. All the above.
Answer Option D
18. Bottom openings 15 cm x 15 cm in the standing baffle wall are provided
A. 15 cm c/c
B. 22.5 cm c/c
C. 30 cm c/c
D. 50 cm c/c.
Answer Option B
19. Faculative bacterias survive in
A. the presence of oxygen
B. the absence of oxygen
C. both cases (a) and (b)
D. neither (a) nor (b).
Answer Option C
20. The ratio of maximum sewage flow to average sewage flow for trunk mains having diameters more than 1.25 m, is
A. 1.5
B. 2.0
C. 3.0
D. 4.0
Answer Option A
21. Acid regression stage of sludge digestion at a temperature 21°C extends over a period of
A. 15 days
B. 30 days
C. 60 days
D. 90 days.
Answer Option D
22. If the pH value of sewage is 7
A. it is acidic
B. it is alkaline
C. it is neutral
D. none of these.
Answer Option C
23. Pick up the correct statement from the following :
A. Maximum daily flow = 2 times the average daily flow
B. Maximum daily flow = x average daily flow
C. Sewers are designed for minimum permissible velocity at minimum flow
D. All the above.
Answer Option D
24. Pick up the incorrect statement from the following :
A. The mixture of water and waste products, is called sewage
B. The treated sewage effluents, are generally used for irrigating the crops
C. The process of collecting, treating and disposing off the sewage, is called sewerage
D. The old convergency system was definitely better than water carried sewerage system
E. None of these.
Answer Option D
25. Pick up the correct statement from the following :
A. Hydrogen sulphide gas in excess, may cause corrosion of concrete sewers
B. 4 ppm of Dissolved Oxygen (D.O.) is ensured before discharging the treated sewage in river
C. Solubility of oxygen in sewage is 95% of that of distilled water
D. Dissolved oxygen content of sewage, may be determined by Winkler's method
E. All the above.
Answer Option E
26. Pick up the correct statement from the following :
A. Small sewers are cleaned by flushing
B. Medium sewers are cleaned by cane rodding
C. Medium sewers may be cleaned by pills
D. Large sewers are cleaned by removing the deposited materials
E. All the above.
Answer Option E
27. Cement concrete sewers are only suitable if non-scouring velocity is between
A. 2.5 to 3.0 m/sec
B. 3.0 to 4.0 m/sec
C. 3.5 to 4.5 m/sec
D. 4.5 to 5.5 m/sec.
Answer Option A
28. The grit chambers of sewage treatment plants, are generally cleaned after
A. 2 days
B. 5 days
C. 7 days
D. 12 days
E. 14 days.
Answer Option E
29. The spacing of bars for perforations in coarse screens used for the treatment of sewage, is
A. 20 mm
B. 30 mm
C. 40 mm
D. 50 mm
E. 100 mm.
Answer Option D
30. In very first stage of decomposition of the organic matter in sewage
A. nitrites are formed
B. nitrates are formed
C. carbondioxide is formed
D. ammonia is formed.
Answer Option D
31. For sewers, inverted siphon is provided for
A. one pipe
B. two pipes
C. three pipes
D. four pipes.
Answer Option C
32. The coagulant which is generally not used for treating the sewage, is
A. alum
B. ferric chloride
C. ferric sulphate
D. chlorinated copperas.
Answer Option A
33. Fresh sewage is generally
A. alkaline
B. acidic
C. highly decomposed
D. a source of objectionable odour.
Answer Option A
34. In a trickling filter
A. filtration process is used
B. biological action is used
C. neither (a) nor (b)
D. both (a) and (b).
Answer Option B
35. If the flame of a miner's safety lamp in a manhole extinguishes within 5 minutes, the sewer certainly contains
A. Hydrogen sulphide
B. Carbon dioxide
C. Methane
D. Oxygen
E. None of these.
Answer Option B
36. The layers of vegetable wastes and night soil alternatively piled above the ground to form a mound, is called
A. a heap
B. plateu
C. windrow
D. none of these.
Answer Option D
37. If the discharge of a sewer running half is 628 1.p.s., i = 0.001, and n = 0.010, the diameter of the sewer, is
A. 1.39 m
B. 1.49 m
C. 1.59 m
D. 1.69 m
E. 1.79 m.
Answer Option D
38. For efficient working of a sewer, it must be ensured that
A. minimum velocity of 0.45 m/sec, is maintained at its minimum flow
B. a maximum velocity of 0.90 m/sec, is maintained at its maximum flow
C. both (a) and (b)
D. neither (a) nor (b).
Answer Option C
39. A manhole is generally provided at each
A. bend
B. junction
C. change of gradient
D. change of sewer diameter
E. all the above.
Answer Option E
40. Pick up the correct statement from the following :
A. Rate of digestion of slugde is more at higher temperature
B. Thermophilic organisms digest the sludge if the temperature ranges from 40° to 60°C
C. Mesophilic organisms digest the sludge if the temperature is between 25° and 40°C
D. 90% of digestion takes place in 30 days at 29°C, the optimum mesophilic temperature
E. All the above.
Answer Option E
41. In Chezy's formula V = C rs for calculating the velocity of flow in circular sewer of diameter D running full, the value of hydraulic mean radius is
A. D
B.
C.
D.
E.
Answer Option D
42. The sewer which collects the discharge from a collecting system and delivers it to a treatment plant, is known
A. house sewer
B. lateral sewer
C. branch sewer
D. sewer outfall.
Answer Option D
43. If the depletion of oxygen is found to be 5 ppm after incubating a 2.5% solution of sewage sample for 5 days at 21°C, B.O.D. of the sewage is
A. 50 ppm
B. 100 ppm
C. 150 ppm
D. 200 ppm
E. 250 ppm.
Answer Option D
44. Setting out the alignments of sewers may start from
A. city
B. out-fall
C. tail end
D. any point.
Answer Option C
45. If the flame of a miner's safety lamp in the upper layers of the sewer forms an explosive, the sewer certainly contains
A. Hydrogen sulphide
B. Carbon dioxide
C. Methane
D. Oxygen
E. None of these.
Answer Option C
46. The underground sewers are more subjected to
A. tensile force
B. compressive force
C. bending force
D. shearing force.
Answer Option B
47. Pick up the correct statement from the following :
A. the sewer pipes of sizes less than 0.4 m diameter are designed as running full at maximum discharge
B. the sewer pipes of sizes greater than 0.4 m diameter are designed as running 2/3rd or 3/4th full at maximum discharge
C. the minimum design velocity of sewer pipes is taken as 0.8 m/sec
D. all the above.
Answer Option D
48. The sewer pipes
A. carry sewage as gravity conduits
B. are designed for generating self-cleansing velocities at different discharge
C. should resist the wear and tear caused due to abrasion
D. all the above.
Answer Option D
49. The normal values of over flow rates for secondary sedimentation tanks, ranges between
A. 25, 000 to 35, 000 litres/sqm/day
B. 40, 000 to 50, 000 litres/sqm/day
C. 50, 000 to 60, 000 litres/sqm/day
D. 80, 000 to 10, 000 litres/sqm/day
E. none of these.
Answer Option A
50. The Brake Horse power of the motor (efficiency 60%) required for a pump of capacity 0.075 cumec for a total lift of 12 m, is
A. 10
B. 15
C. 20
D. 25
Answer Option C
Comments
Post a Comment