Enhanced anaerobic digestion of swine manure via a microbial electrolysis cell and substrate concentration optimisation

Anaerobic digestion (AD) treats swine manure but requires enhancement for optimal performance. This study investigated AD performance assisted by microbial electrolysis cells (MECs) under different substrate concentrations. Using swine manure in MEC-AD and AD reactors, we evaluated methane production, system stability, lignocellulose degradation, energy efficiency, and microbial communities. The MEC-AD achieved maximum methane yield of 284.89 mL/g total solid (TS) at 10% substrate, representing 27.93% increase. System stability improved considerably at 5–15% substrate concentrations. Maximum degradation in MEC-AD reached 70.93% (hemicellulose), 50.02% (cellulose), and 31.90% (lignin). Optimal total energy efficiency (53.12%) and current density (42.02 A m −3 ) were achieved at 10% substrate. Aminobacterium , Syntrophomonas , Methanosarcina , and Methanoculleus positively correlated with methane production. MECs did not enhanced AD performance beyond 15% substrate, revealing a threshold effect in MEC-AD. These findings provide insights into swine manure resource utilisation via MEC-AD, offering solutions for environmental and energy challenges in rural China.