Enhanced membrane-based pre-concentration improves wastewater organic matter recovery: Pilot-scale performance and membrane fouling

Abstract Energy neutrality in municipal wastewater (MW) treatment is an ambitious sustainability goal that is hampered by MW's low organics concentration. A potential method is to pre-concentrate MW to recover the organics and use them to produce energy via anaerobic decomposition. This study conducted a pilot-scale operation using an enhanced membrane-based pre-concentration (MPC) technique to efficiently recover organics from actual MW. Stable and highly efficient organics recovery (72–75%) was achieved during two-month operations. Concentrated organics demonstrated high COD (above 20,000 mg/L) and good anaerobic biodegradability (360–367 mL CH 4 /g VS). Organics recovered by MPC exhibited the potential of net electrical energy production of 0.029–0.050 kWh/m 3 , depending on the fouling situation. The energy consumption of MPC was limited by avoiding continuous intensive aeration. With effective fouling control, as much as 2.91 times more energy could be produced than that was consumed. This suggests MPC-based processes have the potential to transform MW treatment plant from energy consumers to net producers.