Water Treatment MCQ – Environmental Engineering

51. As per W.H.O. standards, the permissible limits of chlorides in drinking water

1. 100 mg/L
2. 200 mg/L
3. 300 mg/L
4. 400 mg/L

52. As per IS 2490-1981, the general tolerance limit for suspended solids in inland surface waters is

1. 30 mg/L
2. 75 mg/L
3. 100 mg/L
4. 60 mg/L

53. Alum as a coagulant is found to be most effective when the pH range of water is

1. 2 to 4
2. 4 to 6
3. 6 to 8
4. 8 to 10

54. Self-purification of running streams may be due to

1. Sedimentation, oxidation and coagulation
2. Dilution, sedimentation and oxidation
3. Dilution, sedimentation and coagulation
4. Dilution, oxidation and coagulation

55. Which of the following is not the characteristic of coliform organisms?

1. Bacillus
2. Gram-negative
3. Ferments lactose
4. Spore-forming

56. In which pollution zone of the river, the dissolved oxygen reduced to zero?

1. Zone of degradation
2. Zone of recovery
3. Zone of clean water
4. Zone of active decomposition

57. In water supply pipes, wrought iron and cast iron pipes have relationship as

1. life of wrought iron pipes > life of cast iron pipes
2. life of cast iron pipes > life of wrought iron pipes
3. both life spans are equal
4. life of wrought iron pipes = 2 (life of cast iron pipes)

58. In water supply, a jar test is performed

1. to obtain the optimal dose of coagulant
2. to find out the optimal time required for flocculation
3. to find the chlorine content of water

The correct statement(s) is/are

1. only 1
2. only 2
3. only 3
4. all of the above

59. D.O. concentration may fall to zero, causing anaerobic conditions in a river reach is called

1. zone of degradation
2. zone of active decomposition
3. zone of recovery
4. none of the above

60. The most common coagulant is

1. chlorine
2. bleaching powder
3. magnesium sulphate
4. alum