Electrochemical ammonia recovery and co-production of chemicals from manure wastewater

Livestock manure wastewater, containing high level of ammonia, is a major source of water contamination, posing serious threats to aquatic ecosystems. Because ammonia is an important nitrogen fertilizer, efficiently recovering ammonia from manure wastewater would have multiple sustainability gains from both the pollution control and the resource recovery perspectives. Here we develop an electrochemical strategy to achieve this goal by using an ion-selective potassium nickel hexacyanoferrate (KNiHCF) electrode as a mediator. The KNiHCF electrode spontaneously oxidizes organic matter and uptakes ammonium ions (NH4+) and potassium ions (K+) in manure wastewater with a nutrient selectivity of ∼100%. Subsequently, nitrogen- and potassium-rich fertilizers are produced alongside the electrosynthesis of H2 (green fuel) or H2O2 (disinfectant) while regenerating the KNiHCF electrode. The preliminary techno-economic analysis indicates that the proposed strategy has notable economic potential and environmental benefits. This work provides a powerful strategy for efficient nutrient (NH4+ and K+) recovery and decentralized fertilizer and chemical production from manure wastewater, paving the way to sustainable agriculture.