Development of a novel two-stage powdered activated carbon-dynamic membrane filtration (PAC-DMF) system for direct physicochemical wastewater treatment

Due to the issues of high energy consumption, high carbon emissions, and low resource and energy recovery, there is an urgent need to develop new paradigms for simultaneous wastewater treatment and resource utilization using physicochemical processes rather than conventional biological means. Recently, direct membrane filtration of municipal wastewater using ultrafiltration/microfiltration technology was proposed and showed satisfactory performance, with high membrane costs and fast membrane fouling as the main limitations. In this study, a novel two-stage powdered activated carbondynamic membrane filtration (PAC-DMF) system was developed using PAC as a carrier to enhance DM formation and organic pollutant retention. The particle size and dosage of PAC, strategy for operating the continuous reactor in the first stage, and selection of the PAC particle size in the second stage were investigated. The effluent from the first stage was found to have a stable water quality, with turbidity in the range of 50–70 NTU. Efficient retention of organic materials was also achieved with a retention rate of 74%–82%, and the COD content in the concentrate was above 3,000 mg/L in the cycle filtration experiment. In the second stage, further enhancement of water quality and organics retention were observed, as evidenced by the low effluent COD (<70 mg/L) and turbidity (5–20 NTU). Meanwhile, the effluent that was rich in nitrogen and phosphorus was suitable for agricultural irrigation or gardening. The results indicated that the developed two-stage PAC-DMF system could be a highly promising alternative to the conventional wastewater treatment process.