True about slow sand filter is –: (A) Occupies less space, (B) More expensive, (C) Requires longer duration, (D) Sand size 0.4 - 0.7 mm
Answer is C. Slow sand filter occupies large area (more space).
Slow and filter requires less skilled operation.
Slow sand filter removes more bacteria and has better bacterial control (99.9-99.99%)
Slow sand filter requires longer duration for purification.
Size of sand is smaller (0.2-0.3 mm).
Slow sand filter requires more time (duration).