Evaluating methane and acetate production in microbial electrolysis cells: reactor performance and microbial diversity

Paper in proceeding, 2013

The work investigated the potential of microbial electrolysis cells (MECs) for methane and acetate production from synthetic wastewater. In a single-chamber MEC operating with acetate as the electron and carbon source, methane and hydrogen were the main reduction products. Acetate consumption as Chemical Oxygen Demand (COD) was 0.26 Kg-COD m-3 d-1, compared to only 0.04 Kg-COD m-3 d-1 in the open circuit control which did not produce considerable biogas amounts. In a similar reactor separated with a cation exchange membrane, acetate could be retrieved from the cathode with an efficiency of up to 85% and rates of 2.5 mM d-1. Phylogenetic analysis revealed that the initial microbial population was enriched with substantially different bacterial species on the two electrodes of each MEC, despite the fact that the electrodes were hydraulically connected. Distinct tasks were carried out by these different microbes, as also supported by the cyclic voltammograms.