Sand Filter MCQ and Rapid Sand Filter MCQ – Environmental Engineering

31. In rapid sand filters, the ratio of length and diameter of lateral should not be greater than

1. 10
2. 15
3. 20
4. 25

32. In rapid sand filter the bacterial impurities of water can be removed up to

1. 90%
2. 70%
3. 50%
4. 30%

33. Ratio of total area of orifices to the filter area served in Rapid sand filter is

1. 0.3% to 0.6%
2. 5% to 10%
3. 0.15% to 5%
4. 4% to 7%

34. In rapid sand filters

1. the effective size of the sand is approx 0.5 mm
2. rate of filtration is of the order of 120-160 m³/m²/day
3. bacteria removal is upto 90%

Of the above statements, the correct statements(s) is/are

1. only i
2. i and ii
3. all of the above
4. ii and iii

35. Uniformity coefficient of filter sand is achieved by

1. D₅₀/D₅
2. D₅₀/D₁₀
3. D₆₀/D₅
4. D₆₀/D₁₀

36. Vacuum filters are used for

1. filtration of sewage
2. filtration of sludge
3. dewatering of sludge
4. both filtration of sewage and filtration of sludge

37. In water treatment, rapid gravity filters are adopted to remove

1. dissolved organic substances
2. dissolved solids and gasses
3. bacteria and colloidal solids
4. floating solids and dissolved inorganic solids

38. In a rapid gravity filter

1. Raw water from a river reservoir is supplied as input
2. Disinfected water is the input
3. Water passed through coagulation tank is the input
4. Water after settling only is the usual input

39. In double filtration, the name of the first filter is

1. pressure filter
2. roughing filter
3. gravity filter
4. rapid sand filter

40. The U.C. (Uniformity coefficient) D₆₀/D₁₀ for best filter media sand should be

1. 5
2. 2
3. 3
4. 4