Question

A water filtration plant consisting of 8 dual-media filters in parallel treats 1.8 m3 /s at an average filtration rate of 10.0 m3 /h.m2 when all units are operating. Each unit is backwashed for 8 minutes every 24 hours with a backwash flow equal to 2.0 % of the filters output. Determine: a) The filtration rate, in m3 /h.m2 , when one out of eight filter units is out for backwashing. b) The backwash rate, in m3 /h.m2 . c) The uniformity coefficient of the sand if it is desired to have at least 15 cm of media intermixing, and the dual media is composed of anthracite with U =1.2, and sand. Assume 10% expansion during backwash.

Answer 1