A Pilot MBR-RO Study for Water Reclamation

The membrane bioreactor (MBR), a combination of conventional activated sludge process (ASP) and membrane separation can produce consistently high quality of effluent from municipal wastewater. Successful pilot studies have already demonstrated the advantages of MBR technology for reclaiming the domestic sewage in Singapore. The objective of this pilot study was to further investigate a new option of the MBR-RO process to produce high grade water directly from domestic sewage. The MBR-RO process was evaluated over five months for its ability to produce better quality effluent. Trial runs on various fluxes of the RO membrane were conducted. Comparison of the new MBR-RO process to the conventional ASP-MF-RO process was also made. The results showed that the new MBR-RO process demonstrated the capability of producing the same or more consistent product quality (in terms of TOC, NH4 and NO3) compared to the conventional ASP-MF-RO process in reclamation of domestic sewage. RO membranes in the MBR-RO process could be operated at 13 gfd without CIP during the whole study period of five months, which was 30% higher than that (10 gfd) in the ASP-UF-RO process for NEWater production. RO permeate quality was improved with increasing the membrane flux. It was concluded that the MBR-RO process could be a new option for NEWater production.