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

Abstract

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 CO₂ 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.