Methanogen Biocathode Microbial Fuel Cell System That Simultaneously Achieves Cattle‐Barn Wastewater Treatment and Carbon Dioxide Utilization

Microbial fuel cells (MFCs) present a promising alternative to traditional activated sludge treatment for livestock wastewater, offering a carbon‐neutral, sustainable approach to wastewater management. Activated sludge treatment requires significant energy input for aeration and produces unpleasant odors. MFCs eliminate the need for energy‐intensive aeration, simultaneously generating energy during wastewater treatment. Platinum‐based electrodes commonly used in the cathode of MFCs pose a significant cost barrier, necessitating advancements in electrode materials for practical, large‐scale application. This study reports on the performance of a continuous methanogen biocathode MFC system engineered to simultaneously treat cattle‐barn wastewater and utilize carbon dioxide without 2‐bromoethanesulfonic acid (BES). Carbon felt treated with nitric acid without BES successfully reduces methane production by 93%. An MFC configuration utilizing nitric acid‐treated carbon felt as the anode and an oak‐derived carbon electrode as the cathode effectively treat wastewater and convert CO 2 to methane, yielding a power density of 5.5 mW m −2 and Coulombic efficiency of 7.3%, approximately twice those without nitric acid treatment and surpassing even the performance of the system with BES treatment. This system represents a promising, low‐cost, and environmentally sustainable approach to renewable energy production and livestock wastewater treatment.