Electrolysis for ammonia removal and hydrogen generation in urban wastewater: Innovative approaches to the water crisis

Abstract

The global water crisis poses significant challenges, with millions lacking access to clean drinking water and increasing water scarcity affecting urban areas worldwide. This study explores the electrolysis of urban wastewater as a two-fold solution for ammonia (un-ionized NH3, and ionized NH4+) removal and hydrogen gas (H2) production. Traditional treatment methods often fail to remove ammonia efficiently, underscoring the need for innovative approaches. Electrolysis, known for its versatility, energy efficiency, and environmental friendliness, emerges as a promising solution in wastewater treatment applications. This research utilized a dimensionally stable electrode (DSA) comprising a Ru-Ir anode and a stainless-steel cathode to electrochemically oxidize ammonia and produce H2. The study investigates the effects of current density, J (83.33–416.6 A/m2) on the treatability of urban wastewater. Maximum H2 production was achieved at J of 416.6 A/cm2 after 300 min reaction time. Under optimal conditions (333.3 A/m2, 0.5 mm inter-electrode distance, and 300 min of operation), the process achieved removal efficiencies of 98.94 % for ammonia, 78.18 % for total suspended solids (TSS), 50.73 % for chemical oxygen demand (COD), and complete removal (∼100 %) of total coliforms. Gas chromatography (GC) assessed the composition of gases of interest generated during electrolysis. This approach addresses environmental pollution and freshwater scarcity and generates an energy resource, presenting a scalable solution for cities worldwide facing similar challenges.