REDUCTION OF FECAL-COLIFORM BACTERIA IN SEWAGE EFFLUENTS USING A MICROPOROUS POLYMERIC MEMBRANE

A study has been undertaken to assess the performance of an extruded, polymeric, tubular, microfiltration membrane with respect to its abili ty to disinfect and clarify sewage effluents. Membranes of two differe nt pore sizes were investigated and the membrane module operated cycli cally with 10 min on and 0.5 min off. Both membranes were seen to be e ffective st improving the physiochemical properties of the sewage effl uents, with significant reductions in suspended solids (SS), chemical oxygen demand (COD) and turbidity. The smaller pore size membrane, how ever, was more efficient at removing faecal coliform bacteria (FCB) fr om the effluents with a rejection that was comparable with existing me mbrane systems. It was seen that breakthrough of FCB occurs at the beg inning of a cycle and that removal efficiency quickly rises to a highe r and more stable level of removal during the cycle. The performance, with reference to FCB rejection, against the primary effluent was sign ificantly better than for the secondary effluent for the larger pore s ize membrane. (C) 1998 Elsevier Science Ltd. All rights reserved.