A Critical Look at Rock Filters

Abstract

Rock filters have been used for more than a decade to remove algal cells from the effluents of sewage lagoons. Previous studies have provided estimates of the serviceable life of rock filters as long as 43 and 55 years. Using mass balance considerations and realistic assumptions concerning the biodegradable fractions of solids and sludge solids-moisture compositions reveal that the serviceable life of these filters will be much shorter.