1. For a continuous flow type of sedimentation tanks
Correct : D. All the above
2. The asbestos cement sewers are
Correct : D. All the above
3. For efficient working of a sewer, it must be ensured that
Correct : C. Both (a) and (b)
4. Bottom openings 15 cm × 15 cm in the standing baffle wall are provided
Correct : B. 22.5 cm c/c
5. For drainage pipes in buildings the test applied before putting them to use, is
Correct : B. Smoke test
6. The pressure exerted by
Correct : D. All the above
7. No treatment of the sewage is given if dilution factor is
Correct : D. More than 500
8. Which of the following pumps in used to pump sewage solids with liquid sewage without
clogging the pump is?
Correct : A. Centrifugal pump
9. Acid regression stage of sludge digestion at a temperature 21°C extends over a period of
Correct : D. 90 days
10. The coagulant which is generally not used for treating the sewage, is
Correct : A. Alum
11. The layers of vegetable wastes and night soil alternatively piled above the ground to form a mound, is called
Correct : C. Windrow
12. If the flame of a miner's safety lamp in the upper layers of the sewer forms an explosive, the
sewer certainly contains
Correct : C. Methane
13. The gas which may cause explosion in sewers, is
Correct : B. Methane
14. Pick up the incorrect statement from the following:
Correct : C. The gases produced in sludge digestion process, contain 75% carbon dioxide
15. The sewer pipes
Correct : D. All the above
16. The settling velocity of the particles larger than 0.06 mm in a settling tank of depth 2.4 is 0.33 m
per sec. The detention period recommended for the tank, is
Correct : D. 2 hours
17. The Chezy's constant C in the formula V = C 𝑟𝑠 depends upon
Correct : D. All the above
18. To prevent settling down of sewage both at the bottom and on the sides of a large sewer,
selfcleaning velocity recommended for Indian conditions, is
Correct : D. 0.75 m/sec
19. Assertion (A): The determination of pH value of sewerage is important. Reason (R): The efficiency of certain treatment methods depends upon the availability of pH value.
Correct : A. Both A and R are true and R is the correct explanation of A
20. The normal values of over flow rates for sedimentation tanks using coagulant, ranges between
Correct : C. 50,000 to 60,000 litres/sqm/day
21. During preliminary treatment of a sewage
Correct : D. All the above
22. Dry weather flow is:
Correct : D. Water supply allowance per capita
23. If q is the average sewage flow from a city of population P, the maximum sewage flow
Correct : D. Q = [(5 + 𝑝 )/(15 + 𝑝 )] q
24. If the flame of a miner's safety lamp in a manhole extinguishes within 5 minutes, the sewer
certainly contains
Correct : B. Carbon dioxide
25. Hydraulic mean radius is
Correct : D. Cross-sectional area/wetted perimeter
26. If the depth of flow in a circular sewer is 1/4th of its diameter D, the wetted perimeter is
Correct : C. 𝝅𝑫𝟑
27. At the junction of sewers
Correct : D. None of these
28. The sewage treatment units in which anaerobic decomposition of organic matter is used, are
called
Correct : B. Trickling filters
29. The sewer which received discharge from two or more main sewers, is known as
Correct : A. A trunk sewer
30. The grit and silt of the grit chambers, may not be used for
Correct : B. Concreting
31. For treating the sewage of a large city, you will recommend
Correct : A. A sedimentation tank and an activated sludge treatment plant
32. Imhoff cone is used to measure
Correct : D. Settleable solids
33. 1000 kg of sewage contains
Correct : D. Both (a) and (c) of above
34. For the COD test of sewage, organic matter is oxidised by K2 Cr2O7 in the presence of
Correct : A. H2SO4
35. The sludge does not contain waste water from
Correct : D. Toilets
36. In sewers the velocity of flow should not be
Correct : B. Less than the self-cleansing velocity
37. In sewers the effect of scouring is more on
Correct : B. Bottom side
38. The sewer which resists sulphide corrosion, is
Correct : D. Lead sewer
39. In a sedimentation tank (length L, width B, depth D) the settling velocity of a particle for a
discharge Q, is
Correct : D. Q/(B × L)
40. The formula which accepts the value of rugosity coefficient n = 0.012 to be used in Manning's
formula, is given by
Correct : B. Crimp and Bruges
41. The amount of oxygen consumed by the aerobic bacterias which cause the aerobic biological decomposition of sewage, is known
Correct : B. Dissolved Oxygen (D.O.)
42. Water content of sewage is about
Correct : D. 9.9 %
43. Skimming tanks are
Correct : A. Used to remove the grease and oil
44. The most efficient cross-section of sewers in a combined sewerage system is
Correct : B. Circular
45. The detention period for plain sedimentation water tanks, is usually
Correct : A. 4 to 8 hours
46. The factor responsible for purification of sewage in river is
Correct : D. All the above
47. Hume steel pipes are
Correct : D. Both (B) and (C)
48. To maintain aerobic biological activity, the moisture content of the compost mass should be
about
Correct : C. 55 %
49. Pick up the correct statement from the following:
Correct : D. The larger the sewer in size, deposition will take place
50. The pH value of sewage is determined with the help of
Correct : C. Potentiometer
51. The normal value of over flow rates for plain primary sedimentation tanks, ranges between
Correct : B. 40,000 to 50,000 litres/sqm/day
52. Which one of the following statements regarding septic tanks is wrong?
Correct : D. The depth of tank is kept equal to its width
53. In areas where rainy season is limited to a few months, the type of sewerage system
recommended is
Correct : C. Separate system
54. The rate of accumulation of sludge in septic tanks is recommended as
Correct : A. 30 litres/person/year
55. Dried sewage after treatment is used as
Correct : A. Fertilizer
56. For drains up to 15 cumecs, the depth “d” and “B” width are related by
Correct : B. d = 0.5 B
57. In areas where light rains are uniformly distributed throughout the year, the type of sewerage
system to be adopted is
Correct : B. Combined system
58. Self-cleansing velocity is
Correct : C. Velocity at which no accumulation remains in the drains
59. 5 days-biochemical oxygen demand (BOD5) is taken at a temperature of
Correct : C. 20°C
60. A well oxidized sewage contains nitrogen mainly as
Correct : A. Nitrates
61. In a sludge tank, the gas mainly produced, is
Correct : D. Carbon dioxide
62. If “D” is the diameter of upper circular portion, the overall depth of New Egg shaped sewer
section, is
Correct : D. 1.625 D
63. In normal conditions, the period for sludge digestion, is
Correct : C. 30 days
64. For evaporation and measurement of settable solids, the apparatus used, is
Correct : D. An Imhoff cone
65. In trickling filter, B.O.D. is reduced to
Correct : C. 60 to 80%
66. For design of sewers, percentage of sewage discharge is assumed
Correct : C. 75 to 80%
67. The grit chambers of sewage treatment plants, are generally cleaned after
Correct : D. 14 days
68. Maximum permissible velocity 1.5 m/sec, is adopted in drains
Correct : C. Both (a) and (b)
69. The average temperature of sewage in India, is
Correct : C. 20°C
70. Pick up the in-correct statement from the following:
Correct : C. Inlets are generally provided in all sewers
71. The moisture content of sludge is reduced from 90% to 80% in a sludge digestion tank. The
percentage decrease in the volume of sludge, is
Correct : B. 50 %
72. If ‘D’ is the diameter of upper circular portion, the overall depth of New Egg shaped sewer
section, is
Correct : D. 1.625 D
73. In trickling filter, B.O.D. is reduced to
Correct : C. 60 to 80%
74. For design of sewers, percentage of sewage discharge is assumed
Correct : C. 75 to 80%
75. The grit chambers of sewage treatment plants, are generally cleaned after
Correct : D. 14 days
76. In the activated sludge process
Correct : B. Aeration is done with an admixture of previously aerated sludge
77. For detecting the nitrates in sewage, the colour may be developed by adding
Correct : C. Phenol-di-sulphuric acid and potassium hydroxide
78. The settling velocity of a spherical particle of diameter less than 0.1 mm as per Stock's law, is
Correct : B. Vs = 418 (Gs - Gw)d² [(3T + 70)/100]
79. Inter-distance between ventilation columns in a sewer line is kept
Correct : D. 150 m to 300 m
80. Stone ware pipes are
Correct : D. Especially suited to pressure pipes
81. The intensity of rain is expressed in
Correct : B. cm/hour
82. The ratio of the diameter of a circular section and the side of a square section hydraulically
equivalent, is
Correct : A. 1.095
83. Which one of the following part of human body withstands minimum radiation?
Correct : D. Ovaries/testis
84. Drop manholes are the manholes
Correct : D. Having drains at different levels
85. The bottom of the sewage inlet chamber of septic tanks, is provided an outward slope
Correct : B. 1 in 10
86. Primary treatment of sewage consists of removal of
Correct : A. Large suspended organic solids
87. Cement concrete sewers are only suitable if non-scouring velocity is between
Correct : A. ) 2.5 to 3.0 m/sec (B) (C) (D)
88. The most widely used pump for lifting sewage is
Correct : A. Centrifugal pump
89. Setting out the alignments of sewers may start from
Correct : C. Tail end
90. The detention time of a circular tank of diameter d and water depth H, for receiving the sewage
Q per hour, is
Correct : A. d² (0.011d + 0.785H)/Q
91. Lead acetate test in sewer manhole is done to test the presence of
Correct : B. Hydrogen sulphide
92. Anti syphonage pipe is fitted
Correct : C. With a W.C. trap
93. In a grit chamber of a sewage treatment plant,
Correct : D. All the above
94. The ratio of maximum sewage flow to average sewage flow for mains up to 1 m in diameter, is
Correct : B. 2.0
95. pH value of sludge during alkaline regression stage, is
Correct : A. More than 7
96. The arrangement made for passing the sewer line below an obstruction below the hydraulic
gradient lines called
Correct : D. all of these
97. Pick up the incorrect size of stone ware sewers
Correct : D. None of these
98. Chlorination of water is done for the removal of
Correct : A. Bacterias
99. Sludge banks are formed if sewage is disposed of in
Correct : B. Seas
100. The clarigesters are
Correct : D. Circular Imhoff double storey tanks without bottom hoppers