Integration of Dark Fermentation with Microbial Electrolysis Cells for Biohydrogen and Methane Production from Distillery Wastewater and Glycerol Waste Co-Digestion

This study aimed to enhance dark fermentative hydrogen production from co-digestion of distillery wastewater (DW) and glycerol waste (GW) through integration with microbial electrolysis cells. First, the optimal proportion of DW and GW in hydrogen production was investigated in batch mode. The results show that DW and GW co-digestion at a ratio of 99:1 (% v/v) gave the highest hydrogen yield of 149.5 mL-H2/g − VSadded. Continuous hydrogen production using the optimal proportion was conducted in a continuously stirred tank reactor. As a result, a maximal hydrogen yield of 99.7 mL-H2/g − VSadded was achieved, and the dominant hydrogen-producing bacterium was Clostridium sensu stricto 7. The dark fermentation effluent from the continuously stirred tank reactor was later used to produce methane using batch MECs. The maximum methane yield of 115.1 mL-CH4/g − VSadded was obtained under an applied voltage of 1 V and continuous stirring at 120–140 rpm. Microbial community analysis revealed that Metahnobacterium, Methanomethylovorans, Methanoculleus, and Methanosarcina were the methanogenic archaea in the microbial electrolysis cell reactor.