Combined Biological and Electrochemical Process to Produce Ammonia Fuel from High-Strength Blackwater

This study develops a biological-electrochemical process for ammonia fuel production from high-strength blackwater, integrating enhanced ammonification, anaerobic digestion (AD), and electrodialysis (ED). The system achieved 90% COD removal, with Bacillus subtilis increasing NH₃-N concentrations by 113%, enhancing nitrogen recovery. AD reduced volatile solids by 60%, producing 200 mL/day of biogas with 70% methane content, and increased NH₃-N from 215 to 308 mg/L in the effluent. ED concentrated ammonia to 3 g NH₃-N/L with an energy consumption of 1.8 Wh/L, while diluted effluent contained <30 mg NH₃-N/L. The system generated a net energy output of 20.48 kWh-e/day, transforming wastewater from an energy sink into an energy-positive process. This approach enables high-efficiency nitrogen recovery, converting waste into ammonia fuel for reformation efforts, while supporting decentralized sanitation solutions.