Question

The finer the suspended impurities to be removed ___________

(a) Larger will be the sand size

(b) Smaller will be the sand size

(c) Smaller will be the surface area of sand grains

(d) Narrow will be the sand depth of the bed

This question was posed to me in a job interview.

Question is taken from Rapid Sand Filter topic in section Filtration of Environmental Engineering

Answer 1

Correct answer is (b) Smaller will be the sand size

Explanation: The finer the suspended impurities to be removed, smaller will be the sand size in order to increase the surface area of sand grains in the sand bed.