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.

高氨浓度的畜禽养殖粪污废水是水体污染的主要来源之一，对水生生态系统构成严重威胁。由于氨是重要的氮肥原料，从粪污废水中高效回收氨，无论从污染防控还是资源回收的角度而言，均可实现多重可持续发展效益。在此，我们开发了一种电化学策略以实现该目标，采用离子选择性六氰合铁酸钾镍（KNiHCF）电极作为介质。该KNiHCF电极可在粪污废水中自发氧化有机质，并以约100%的营养物选择性捕获铵离子（NH₄⁺）与钾离子（K⁺）。随后，在电极再生的同时，可伴随氢气（绿色燃料）或过氧化氢（消毒剂）的电合成过程，制备出富氮富钾肥料。初步技术经济分析表明，所提出的策略具备显著的经济潜力与环境效益。本研究为从粪污废水中高效回收营养物质（NH₄⁺与K⁺）、实现分布式肥料与化学品生产提供了一种高效策略，为可持续农业发展铺平了道路。