Mitigation of Volatile Fatty Acid Build-Up by the Use of Soft Carbon Felt Electrodes: Evaluation of Anaerobic Digestion in Acidic Conditions

Anaerobic digestion and bioelectrochemical systems have great potential to recover energy from waste streams and help overcome common hurdles associated with this process, as integrated technologies. In this study, the benefit of integrating an electrogen-enriched bioanode in a batch anaerobic digester was explored under ambient temperature conditions associated with organic overloading and reactor acidity. An increase in CH4 production was observed in the electrode-containing reactors (0.56 L CH4 kgVS−1 h−1) in comparison with the conventional anaerobic digester (0.14 L CH4 kgVS−1 h−1) during the initial stages of operation. In addition, the mere presence of electrodes operating in open circuit mode resulted in a delay in volatile fatty acid (VFA) build-up. This seems to be associated with the enhancement in VFA consumption due to biomass proliferation on the electrode surface, rather than on electrochemical activity.