Waste Water Engineering

51. Flocculated particles do not change their

1. Size
2. Shape
3. Weight
4. None of these

View answer

52. For a circular sewer of diameter 'D' running partially full with central angle α,

1. d/D = ½ (1 - cosα/2)
2. a/A - [π/360°) - (sinα/2π)]
3. r/R = [1 - 360°) - (sinα/aπ)]
4. All the above

View answer

53. For a continuous flow type of sedimentation tanks

1. Width of the tank is normally kept about 6 m
2. Length of the tank is normally kept 4 to 5 times the width
3. Maximum horizontal flow velocity is limited to 0.3 m/minute
4. All the above

View answer

54. For a grit chamber, if the recommended velocity of flow is 0.2 m/sec and detention period is 2 minutes, the length of the tank, is

1. 16 m
2. 20 m
3. 24 m
4. 30 m

View answer

55. For a peak discharge of 0.0157 cumec, with a velocity of 0.9 m/sec, the diameter of the sewer main, is

1. 10 cm
2. 12 cm
3. 15 cm
4. 18 cm

View answer

56. For design of sewers, percentage of sewage discharge is assumed

1. 65 to 70%
2. 70 to 75%
3. 75 to 80%
4. 0.85

View answer

57. For design purposes, the normal rate of infiltration of ground water into the sewer, is

1. 500 litres/km/cm
2. 1000 litres/km/cm
3. 1500 litres/km/cm
4. 2000 litres/km/cm

View answer

58. For detecting the nitrates in sewage, the colour may be developed by adding

1. Potassium permanganate
2. Sulphuric acid and napthamine
3. Phenol-di-sulphuric acid and potassium hydroxide
4. None of these

View answer

59. For detecting the nitrites in the sewage, the matching colour may be developed by adding

1. Potassium permanganate
2. Sulphuric acid and napthamine
3. Phenol-di-sulphuric acid potassium hydroxide
4. None of these

View answer

60. For drainage pipes in buildings the test applied before putting them to use, is

1. Water test
2. Smoke test
3. Straightness test
4. All the above

View answer