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A pilot study was conducted to evaluate the quality of the effluent of an enhanced tertiary treatment process consisting of MBR/RO or MF/RO units and explore the feasibility of reclamation of treated effluent for potable and non-potable reuse applications. The performance of both the MBR/RO and MF/RO pilot plants was excellent. The MBR or MF alone was able to bring down the concentrations of most of the pollutants under acceptable limits for non-potable reuse applications. The application of RO further improved the treated water quality, especially the aesthetical and microbial qualities. Different strategies were employed to control membrane fouling in RO, and hypochlorite dosing showed the best results. The RO permeate quality in terms of conductivity, turbidity, organic content, ammonia, nitrate, hardness, E. coli and virus could meet the water quality requirements for many potable and non-potable reuse applications. In removal of total estrogens, the MBR/RO combination performed better than that of MF with RO, indicating the importance of the role of biomass. The rejection of virus in MBR and MF was greatly affected by the chemical membrane cleaning. It took more than 24 h for the recovery, implying that the presence of membrane biofilm plays a key role in rejection of virus.

The results of this pilot trial illustrated that the MBR/RO and MF/RO technologies can be used to treat raw sewage and secondary effluent, respectively to produce reclaimable water. The operations of both the pilot plants were stable and the performances were excellent. The MBR was able to remove organic matter and nitrogen to an acceptable level and at the same time achieve impressive virus and E. coli rejection. The test results from the comprehensive physical, chemical and microbiological study in this pilot trial showed that the quality of RO-permeate exceeded the requirements of the drinking water stipulated in the USEPA and WHO guidelines. The pilot trial with two different RO membranes showed comparable results. Production of “optimized water” for toilet flushing to optimize the treatment cost was illustrated.