Ammonium Recovery from Manure Wastewater and Simultaneous Electrosynthesis using Ammonium-Ion Selective Redox Material

The greenhouse gas emissions and water contamination generated by livestock manure motivates the development of new approaches to reduce their environmental impacts and improve sustainability. Effective approaches to recover nutrients, especially ammonia, from manure wastewater to produce fertilizer are needed. Here we develop a new electrochemical strategy to achieve simultaneous ammonium (NH₄⁺) ion recovery and electrochemical synthesis using potassium nickel hexacyanoferrate (KNiHCF) as the ammonium ion-selective redox material to mediate the process. The KNiHCF electrode spontaneously uptakes NH₄⁺ (and K⁺) from manure wastewater with a nutrient (NH₄⁺ and K⁺) selectivity of ~100% and oxidizes the organic matter. Subsequently, NH₄⁺-rich fertilizers are released electrochemically together with the electrosynthesis of value-added chemicals, such as H₂ as a green fuel or H₂O₂ as a disinfectant, without expensive ion-exchange membranes. The integrated process shows an estimated net profit for common cow dairy farms and could potentially reduce NH₃ emissions. These results provide a new conceptual strategy for distributed electrochemical resource recovery and on-demand electrochemical manufacturing that can improve agricultural sustainability and also open new opportunities for selective metal ion recovery towards zero liquid discharge water treatment and purification.