Low-cost membranes for use in a submerged MBR

Capital costs of a MBR (Membrane Bio-Reactor) process are substantially inf luenced by the membrane cost itself, which contributes around 50% of the to tal process capital cost. The feasibility of a submerged MBR fitted with th ree pore-sized NWPP (Non-Woven Poly-Propylene) membranes has been studied. The performance was compared with that of a conventional polysulfone (PS) m embrane material. Both the PS and NWPP membranes demonstrated a drastic red uction in permeate flux at the start of operation. Although the NWPP membra ne showed a greater fouling propensity than the PS membrane, the difference in flux decline between the two membranes was not great. All membranes pro duced an effluent extremely low in organic matter and with a low permeate t urbidity (<1 NTU), and ammonia removal was higher than 60% in all cases. Ho wever, whereas the PS membrane achieved a 7-log reduction in total coliform s, the NWPP membranes achieved only a 2 to 4-log reduction. Consequently, l ow-cost NWPP membranes can be considered suitable for use in MBR processes for municipal wastewater treatment, but are possibly less suited to domesti c: wastewater reuse where disinfection is a prerequisite.