Electrodialysis and Nitrate Reduction to Enable Distributed Ammonia Manufacturing from Wastewaters

Underutilized wastewaters containing dilute levels of reactive nitrogen (Nr) can help rebalance the nitrogen cycle. This study describes electrodialysis and nitrate reduction (EDNR), a reactive electrochemical separation architecture that combines catalysis and separations to remediate nitrate and ammonium-polluted wastewaters while recovering ammonia. By engineering operating parameters (e.g., background electrolyte, applied potential, electrolyte flow rate), we achieved near-complete recovery and conversion of Nr in both simulated and real wastewaters. EDNR process demonstrated long-term robustness and recovered >100 mM ammonium fertilizer solution from 8.2 mM Nr-containing agricultural runoff. EDNR is the first reported process to our knowledge that remediates dilute real wastewater and recovers ammonia from multiple Nr pollutants, with an energy consumption (245 MJ/kg NH3-N in simulated wastewater, 920 MJ/kg NH3-N in agricultural runoff) on par with the state-of-the-art. Demonstrated first at proof-of-concept and engineered to technology readiness level (TRL) 5, EDNR shows great promise for distributed wastewater treatment and sustainable ammonia manufacturing.