True about slow sand filter is -
Option A - wrong, slow sand filter occupy more space Option B - wrong, it is less expensive Option C - correct, rate of filtration is very slow (2-3m.g.a.d.) hence takes longer time Option D - wrong, effective sand size in slow sand filter is 0.2-0.3 mm (PARK TB 25th edition pg 773)
Occupies less space
More expensive
Requires longer duration
Sand size 0.4-0.7 mm
Environment and health