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An innovative anaerobic MBR-reverse osmosis-ion exchange process for energy-efficient reclamation of municipal wastewater to NEWater-like product water

Gu, Jun, Liu, Hang, Wang, Siyu, Zhang, Meng, Liu, Yu
Journal of cleaner production 2019 v.230 pp. 1287-1293
ammonium, chemical oxygen demand, energy efficiency, energy recovery, membrane bioreactors, methane, microfiltration, municipal wastewater, organic carbon, phosphates, population growth, reverse osmosis, sludge, urbanization, wastewater treatment, water quality, Singapore
The rapid population growth and urbanization have led to an increasing need on recycle and reuse of municipal wastewater. In the current practice for high-grade reclaimed water production, municipal wastewater was first treated by conventional biological process, and further purified through microfiltration and reverse osmosis. However, such a multi-stage process has received more and more critiques due to the process complexity, intensive energy consumption, excessive sludge production and large footprint. To address these emerging issues, this study evaluated the feasibility of an innovative integrated anaerobic membrane bioreactor (AnMBR)-reverse osmosis (RO)-ion exchange (IE) process for treatment of municipal wastewater to high-grade reclaimed water with high energy efficiency and minimized waste sludge production. In this integrated process, an AnMBR was employed as the lead for energy recovery through direct COD capture, and AnMBR effluent was subsequently reclaimed to NEWater-like product water through combined RO and IE. Results showed that nearly 76.8% of influent COD was converted to methane in AnMBR equivalent to 0.41 kWh/m3 wastewater treated, while more than 95% of organic carbon, ammonium, phosphate, major ions and cations in AnMBR effluent were rejected by RO. After further polishing by IE, the product water quality appeared to be comparable or even better than the typical NEWater quality in Singapore. This study showed that the integrated AnMBR-RO-IE process could produce NEWater-like product water with compact footprint, near-zero sludge production, high operation stability, maximized energy recovery and reduced energy consumption compared to the current process for NEWater production from municipal wastewater. It is expected that the proposed process can offer new insights into the direction of future wastewater reclamation.