ASPECTS OF MICROFILTRATION AND REVERSE-OSMOSIS IN MUNICIPAL WASTE-WATER REUSE

This paper discusses some of the key issues for reclamation of seconda ry effluent by membranes. The process considered using microfiltration (MF) as pretreatment prior to reverse osmosis (RO). The paper describ es the application of ''critical flux'' operation to optimise flux thr ough the MF membrane. Transmission of the polio virus through the 0.2 mu m pore MF membrane was minimised at low pressure, with crossflow an d in the presence of biomass; log reductions of 2 were observed. For f eed containing significant levels of sewage bacteria, the passage of s mall (0.2-0.3 mu m sized) bacteria was observed, although log reductio ns were >4. Bacterial bioadhesion studies of various RO membranes show ed significant differences between membranes, the least adsorptive bei ng hydrophilic, Further studies are required to optimise the use of me mbrane-based reclamation of secondary effluent.