Evaluating Membrane Bioreactor Performance When Used with RO for Water Reclamation in Singapore

Abstract

A large pilot study was conducted in Singapore to evaluate the performance of membrane bioreactors (MBRs) when used with reverse osmosis (RO), particularly focusing on energy consumption. MBRs using microfiltration (MF) membranes made from polyvinylidene difluoride were set up with anoxic, aeration, and day membrane tanks at wastewater treatment plants in Bedok and Ulu Pandan, Singapore. During commissioning, the energy demand of the MBRs was dramatically decreased by increasing the amount of treated water that was calculated by flux. After commissioning, MBR minimum specific energy demand was 0.57 kW·h/m³ in the case of 33-lmh flux operation. Based on the MBR–RO pilot test for treating municipal wastewater, suitable MF and RO flux were 35 lmh and 20.8 lmh, respectively, without clean-in-place procedures for a longterm operation. For stable operation of the RO process, chloramines had a positive effect on RO membrane permeability. It was demonstrated that high-quality product water, stable MF/RO membrane operation, and low energy consumption could be achieved with MBR–RO.