Enhancing Biogas Production and Methane Yields Through Microbial Electrolysis Cell-Assisted Anaerobic Digestion in a Fed Batch Reactor

To address the limitations of conventional anaerobic digestion (AD), this study explored the integration of microbial electrolysis cells (MECs) with AD to improve biogas production and process stability. While AD is a proven technology for renewable energy recovery from waste, it can suffer from volatile fatty acid accumulation and reduced efficiency. The hybrid MEC–AD system leverages electro-methanogenesis to enhance methane yields and overall system performance. This research evaluated the effects of different electrode materials (graphite plate vs. graphite felt) and applied voltages (0.5 V and 0.7 V) on biogas output, methane content, and operational stability. Results showed that MEC–AD systems significantly outperformed conventional AD, with the highest biogas production reaching 239 ± 3 mL/gVS·d—an increase of up to 162% using graphite felt electrodes at 0.5 V. Internal resistance was also markedly lower with graphite felt (19 Ω/m2) compared to graphite plates (1120 Ω/m2). Furthermore, the pH of the MEC–AD system with graphite felt electrodes was maintained within the optimal range (6.8–7.0), avoiding the acidification seen in control systems. These findings underscore the promise of MEC–AD systems for advancing circular bio-economy initiatives and carbon neutrality. Further work is needed to refine electrode materials and reactor design for improved scalability and efficiency.