Water Treatment MCQ – Environmental Engineering

31. Dechlorination of water is achieved by adding

  1. Sodium thiosulphate
  2. Sodium sulphate
  3. Sodium biosulphate
  4. None of these
Answer
Answer. a

32. In a water treatment plant, dissolved iron and manganese can be removed by

  1. Aeration
  2. Aeration and flocculation
  3. Aeration and coagulation
  4. Aeration and sedimentation
Answer
Answer. d

33. Which of the following is not used as coagulant in water treatment?

  1. alum
  2. hydrated ferrous sulphate and lime
  3. sodium carbonate
  4. chlorinated copperas
Answer
Answer. c

34. A fluoride concentration of __________ in water is beneficial for the prevention of dental caries in children.

  1. 0.1 p.p.m. to 0.6 p.p.m.
  2. 0.7 p.p.m. to 1.2 p.p.m.
  3. 1.4 p.p.m. to 2.0 p.p.m.
  4. 2.5 p.p.m. to 3.0 p.p.m.
Answer
Answer. b

35. Which of the following is not a unit process in water treatment systems?

  1. Coagulation
  2. Flocculation
  3. Adsorption
  4. Softening
Answer
Answer. b

36. Which one of the following treatment is economically effective in the control of guinea worm disease?

  1. Filtration
  2. Chlorination
  3. Sedimentation
  4. Ozonation
Answer
Answer. a

37. The process in which the chlorination is done beyond the breakpoint is known as

  1. post chlorination
  2. super chlorination
  3. breakpoint chlorination
  4. hyper chlorination
Answer
Answer. b

38. The second stage of water treatment is

  1. Disinfection
  2. Mixing and Coagulation
  3. Sedimentation
  4. Filtration
Answer
Answer. c

39. Alum increases

  1. sulphates in water
  2. hardness of water
  3. carbonates of water
  4. acidity of water
Answer
Answer. d

40. Removal of excessive iron from public water supply is usually done by

  1. chemical precipitation
  2. aeration
  3. ion exchange
  4. coagulation
Answer
Answer. b
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