Sewerage System MCQ – Environmental Engineering

1. In very first stage of decomposition of the organic matter in sewage

  1. Nitrites are formed
  2. Nitrates are formed
  3. Carbon dioxide is formed
  4. Ammonia is formed
Answer. d

2. The means of access for inspection and cleaning of sewer line is known as

  1. Inlet
  2. Manhole
  3. Catch basin
  4. Drop manhole
Answer. b

3. Removal of oil and grease from sewage is known as

  1. Screening
  2. Skimming
  3. Filtration
  4. All of the above options
Answer. b

4. Combined system of sewers may be favoured where

  1. Rainfall is concentrated in a season of the year and DWF is often fluctuation from day to day
  2. Rainfall is scattered throughout the year and DWF is too small compared to storm water
  3. Rainfall is distributed throughout the year such that it is ≤ 10 × DWF
  4. City is on steep rocky slopes
Answer. c

5. A well 0xidized sewage contains nitrogen mainly as

  1. Nitrates
  2. Nitrites
  3. Ammoniacal Nitrogen
  4. Free ammonia
Answer. a

6. A combined sewage system collectively carries

  1. domestic sewage and industrial sewage
  2. storm sewage and domestic sewage
  3. storm sewage and industrial sewage
  4. storm domestic and industrial sewage
Answer. b

7. The drop manholes are provided in sewerage system when there is

  1. Change in alignment of sewer line
  2. Change in size of sewers
  3. Change in the elevation of ground level
  4. Change from gravity system to pressure system
Answer. c

8. Manhole covers are made circular

  1. To strengthen the cover
  2. To make the entry convenient
  3. For architectural reason
  4. To prevent falling of the cover into the manhole
Answer. d

9. Manholes on sewer lines are provided for

  1. Period cleaning
  2. Providing air for oxidation
  3. Removal of part of sewerage
  4. All of the above
Answer. d

10. The most suitable sewer in combined sewerage system is

  1. Circular
  2. Rectangular
  3. Parabolic
  4. Egg shaped
Answer. d

11. A drop manhole is provided in a sewerage system, when there is

  1. change from gravity system to pressure system
  2. change in elevation of ground level
  3. change in alignment of sewer line
  4. change in size of sewer
Answer. c

12. Sewerage system is usually designed for

  1. 7 years
  2. 5 years
  3. 100 years
  4. 25 years
Answer. d

13. Pickup the incorrect statement from the following

  1. the mixture of water and waste products is called sewage.
  2. the treated sewage effluents are generally used for irrigation crops.
  3. the process of collecting, treating and disposing the sewage is called sewerage.
  4. the old conservancy system was definitely better than water carried sewerage system
Answer. d

14. A drop manhole may be provided along the sewer line

  1. To provide inspection channels in the sewer line
  2. When a branch sewer outfalls into it from a height of more than 0.6 or 0.9
  3. To provide self cleaning velocity in the sewer line
  4. None of the above
Answer. b

15. Manholes on sewer lines are provided for

  1. removal of part of sewage
  2. periodic cleaning
  3. providing air for oxidation
  4. all of three mentioned here
Answer. b

16. Which of the following is FALSE about vitrified sewer pipes?

  1. Highly resistant to sulphide corrosion
  2. Highly imperious
  3. High compressive strength
  4. Light weight
Answer. d

17. Which one of the following options is true for combined system of sewerage system?

  1. Sewage and rain water
  2. Dry weather flow and rain water
  3. Sewage and industrial waste
  4. Industrial waste and rain water
Answer. b

18. Type of pumps most generally used in sewage pumping area

  1. axial flow screw pumps
  2. air ejectors
  3. centrifugal pumps
  4. submersible pumps
Answer. a

19. In a sewerage system, flushing tank is located at

  1. intersection of two sewers at different levels
  2. at summit end of sewer
  3. sewer line with steep gradient
  4. intersection of two sewers of different sizes
Answer. c

20. The water carried sewerage system removes

  1. Industrial sewage
  2. Domestic sewage
  3. Storm sewage
  4. All the above
Answer. d

21. The sewer pipes have to be designed and checked for

  1. only maximum flow
  2. average flow
  3. both maximum and minimum flow
  4. only minimum flow
Answer. c