Enhanced Methane Production in Anaerobic Membrane Bioreactors: The Role of In-Situ Electro-Stimulation

This study compared the 280-day performance of a granular anaerobic membrane bioreactor (GAnMBR) and its electro-assisted variant (eGAnMBR) treating domestic wastewater at ambient temperature across permeate fluxes of 1.7-5.9 L/m²/h. Both systems achieved >95 % chemical oxygen demand removal. At moderate flux, eGAnMBR improved methane recovery by around 15 % versus the control and produced biogas up to 94 % methane. Lower effluent methane saturation suggested reduced dissolved-methane losses and lower greenhouse-gas risk. Despite slightly higher resistance from near-electrode cake, >95 % of fouling remained reversible; targeted design and operational optimization to limit cake and enhance local shear should support scale-up. Both systems remained net-energy-positive, with energy recovery above 0.76 kWh/m³ at the highest loading and clearer eGAnMBR benefits at moderate loading and shorter hydraulic retention time. Overall, electro-stimulated GAnMBR improved methane valorization and process robustness while preserving a net-positive energy balance, indicating a practical path to scalable, low-carbon municipal treatment.