Question

The filtration rate of a slow sand filter is _____ litres of water per square metre.

(a) 20

(b) 30

(c) 50

(d) 100

This question was addressed to me during an online exam.

This intriguing question originated from Theory and classification of Filtration topic in chapter Filtration of Environmental Engineering

Answer 1

Right answer is (d) 100

For explanation I would say: The surface area of the slow sand filter lies between 50m^2 to 1000m^2 and its filtration rate lies between 100 to 200 litres of water per m^2.