MATHEMATICAL-MODELING OF DOWNFLOW FLOATING MEDIUM FILTER (DFF) WITH IN-LINE FLOCCULATION ARRANGEMENT

A laboratory-scale set-up consisting of rapid mixing device and floati ng medium filter was used to study the use of a downflow floating medi um filter (DFF) with an in-line flocculation arrangement as a static f locculator and a prefilter. The semi-empirical mathematical model form ulated incorporates flocculation within the filter, particle/floc atta chment onto the filter and the detachment of flocs from the medium. Th e mathematical model for filtration takes into account the expansion o f the filter bed. The removal efficiency of DFF and headless developme nt were successfully simulated for different conditions of filtration velocity, filter depth and influent suspended solids (SS). The values of attachment coefficient a(p) beta and headless coefficient beta' wer e found to be independent of filtration velocity, filter depth and inf luent SS concentration. Copyright (C) 1996 IAWQ. Published by Elsevier Science Ltd.