Question

In which of the following filters, the rate of filtration is highest?

(a) Slow sand filter

(b) Rapid sand filter

(c) Pressure filter

(d) Roughing filter

The question was asked at a job interview.

Question is from Comparison Between Slow and Rapid Sand Filter in section Filtration of Environmental Engineering

Answer 1

The correct option is (c) Pressure filter

For explanation I would say: The rate of filtration is highest in pressure filter and its filtration rate lies between 6000 to 15000 litres per hour per m^2 of filter area while in rapid sand and roughing filter, it is between 6000 to 8000 litres per hour per m^2 of filter area.