The synergistic effect of H2 injections and applied potential on biogas production during the treatment of industrial potato processing wastewater in a Microbial Electrolysis Cell-assisted Anaerobic Digestion system

This study deals with the synergistic effect H2 supply and applied potential, during the treatment of industrial pota-to processing wastewater in a Microbial Electrolysis Cell-assisted Anaerobic Digestion (MEC-AD) system, in order to enhance the quality of the produced biogas. The MEC-AD reactor was equipped with carbon felt electrodes and operated for 80 d at a constant Hydraulic Retention Time of 15 d. The results showed that when H2 was supplied in excess, the MEC-AD reactor failed, due to the inhibition of hydrolysis, acid accumulation, pH increase and en-richment of hydrogen sulfide producing bacteria. Never-theless, when H2 was supplied through saturating the feed, the reactor operated stably, leading to a COD re-moval of 92.6% and exhibited enhanced biogas quality, producing a CH4:CO2 ratio of 2.9, relative to 1.1 when no H2 was supplied. Overall, the combined effect of hy-drogenotrophic methanogenesis and electromethanosyn-thesis represents a promising strategy for enhancing bio-gas quality, while simultaneously enabling the synergis-tic integration of bioelectrochemical and anaerobic pro-cesses to mitigate failure mechanisms associated with elevated H2 partial pressures.