Microenvironment-engineered electrified membrane for reactive separation of ammonia from wastewater

Source-separated recovery of nitrogen pollutants can enable nitrogen circularity and reduce the burden on wastewater infrastructure, yet most electrochemical systems struggle to couple high flux with low energy consumption. Here, we report a reagent-free electrified membrane that generates interfacial alkalinity via water dissociation at the membrane-wastewater boundary, drives ammonium (NH 4 + ) to ammonia (NH 3 ) conversion, and continuously extracts NH 3 across the membrane as a high-purity stream. An integrated microenvironment-engineered design increases interfacial alkalinity and reduces gas-transport resistance, thereby optimizing NH 4 + /NH 3 speciation and transmembrane flux with low energy consumption. The electrified membrane achieves the highest reported NH 3 separation rate among electrochemical recovery systems and averages 2.9 times that of conventional structure while retaining 87.5% of its initial performance after 500 hours of flow-type operation. Preliminary building-scale life-cycle assessment and techno-economic analysis indicate notable environmental benefits and economic potential, with 2.34 square meters of membrane achieving a 95% NH 3 recovery target for a 440-resident apartment. This work sets a framework for electrochemical NH 3 separation and outlines a pathway to practical, decentralized deployment.