21. Which of the following unit works in anaerobic conditions ?
A. sludge digestion tank
B. sedimentation tank
C. activated sludge treatment
D. trickling filters
✅ The correct answer is option A.
Environmental Engineering MCQs
22. The main disadvantage of oxidation pond is that________________?
A. large area is required for construction
B. maintenance and operation cost are high
C. BOD removal is very low
D. none of the above
✅ The correct answer is option A.
23. For a country like India, where rainfall is mainly confined to one season, the suitable sewerage system will be________________?
A. separate system
B. combined system
C. partially combined system
D. partially separate system
✅ The correct answer is option A.
24. Which of the following values of pH represents a stronger acid?
A. 2
B. 5
C. 7
D. 10
✅ The correct answer is option A.
25. The method of analysis of distribution system in which the domestic supply is neglected and fire demand is considered is________________?
A. circle method
B. equivalent pipe method
C. electrical analysis method
D. Hardy cross method
✅ The correct answer is option A.
26. Sludge volume index is defined as the ratio of_______________?
A. percentage of sludge by volume to percentage of suspended solids by weight
B. percentage of sludge by volume to percentage of total solids by weight
C. percentage of suspended solids by weight to percentage of sludge by volume
D. percentage of total solids by weight to percentage of sludge by volume
✅ The correct answer is option A.
27. The water carriage system of collection of waste product________________?
A. is cheaper in initial cost than dry conservancy system
B. requires treatment before disposal
C. creates hygenic problem
D. all of the above
✅ The correct answer is option B.
28. For the same solid content, if the quantity of sludge with moisture content of 98% is X, then the quantity of sludge with moisture content of 96% will be__________________?
A. X/4
B. X/2
C. X
D. 2X
✅ The correct answer is option B.
29. The pipe which is used to carry the discharge from sanitary fittings like bath rooms, kitchens etc. is called_______________?
A. waste pipe
B. soil pipe
C. vent pipe
D. antisiphonage pipe
✅ The correct answer is option A.
30. The settling velocity of a particle in a sedimentation tank depends on__________________?
A. depth of tank
B. surface area of tank
C. both depth and surface area of tank
D. none of the above
✅ The correct answer is option B.