Sand Filter MCQ and Rapid Sand Filter MCQ – Environmental Engineering

21. The maximum spacing of laterals in a rapid sand filter can be

1. 10 cm
2. 30 cm
3. 50 cm
4. 100 cm

22. In rapid sand filters, the depth of tank varies in between

1. 2.5 m to 3.5 m
2. 1 m to 2 m
3. 0.6 m to 0.9 m
4. 3 m to 3.5 m

23. The yield of rapid sand filter is __________ to that of slow sand filter.

1. 15 times
2. 10 times
3. 30 times
4. 20 times

24. As compared to slow sand filters rapid sand filters give

1. lower filtration rate and lower efficiency in removal of bacteria
2. lower filtration rate but higher efficiency in removal of bacteria
3. higher filtration rate but lower efficiency in removal of bacteria
4. higher filtration rate and higher efficiency 1n removal of bacteria

25. The standard rate of filtration through a rapid sand filter is usually

1. 50-60 litre per minute per m²
2. 80-100 litre per minute per m²
3. 120-150 litre per minute per m²
4. 150-180 litre per minute per m²

26. For rapid sand filter, sand should have the following specifications

1. Effective size = 0.1 -0.5 mm
   Uniformity coefficient 2 to 4
2. Effective size = 0.2 – 0.5 mm
   Uniformity coefficient = 2 to 3
3. Effective size = 0.45 – 0.7 mm
   Uniformity coefficient = 1.3 to 1.7
4. Effective size = 0.7 -0.9 mm
   Uniformity coefficient = 1 to 5

27. Cleaning of rapid sand filters is done by

1. providing new sand layers
2. scraping the top layer of filter media
3. back washing
4. all of three mentioned here

28. The period of cleaning for rapid sand filter is

1. 2-3 months
2. 24-48 months
3. 24-48 hours
4. 24-48 weeks

29. The maximum permitted loss of head in a rapid sand filter is

1. 2 m
2. 1 m
3. 4 m
4. 3 m

30. Effective size to be used in rapid sand gravity filter is

1. 0.45-0.70 mm
2. 0.15 – 0.30 mm
3. 0.95 – 1.100 mm
4. 0.75 -0.90 mm