A cathodic electro-fermentation system for enhanced methane production from high-concentration potato starch industrial wastewater

The high chemical oxygen demand (COD) concentration of potato starch industrial wastewater makes it very challenging for traditional anaerobic digestion (AD) to treat. Here we proposed to use the cathodic electro-fermentation system to enhance the methane production from potato starch industrial wastewater (7546 mg·L−1 COD). Compared with the traditional AD, the electro-fermentation system enhanced the maximum methane production rate more than three times and increased the cumulative methane production by 30 %. What's more, the lag phase of the AD was dramatically reduced, and the COD degradation rate was significantly improved in the electro-fermentation system. The better performance could be attributed to the fact the electro-fermentation system could avoid the accumulation of the intermediate metabolites (e.g. volatile fatty acids (VFAs)) and maintain a suitable pH for methanogens. Additionally, the applied potential at the cathode enhanced the acidification and methanation process and enabled a more stable microbial community. This study demonstrated that electro-fermentation is an efficient way to treat high-concentration potato starch industrial wastewater for methane production.