Carbon dioxide abatement and biofilm growth in Mec equipped with a packed bed adsorption column

In this study, a lab-scale microbial electrolysis cell (MEC) aimed to the biogas upgrading through a methanogenic biocathode has been integrated with an adsorption column to test the possible increase of the biocathode CO2 removal capacity. In the adopted MEC configuration, the oxidation of the organic matter by an anodic biofilm was utilized to partially sustain the energy demand of the bioelectromethanogenesis reaction in the cathodic chamber. Anodic and cathodic biofilms were characterized by cyclic voltammetry (CV) technique which allowed the electron transfer mechanisms characterization in the anodic and cathodic bioelectrochemical reactions. More in detail, while the anodic biofilm showed the presence of a potential direct electron transfer, the cathodic CV suggests a hydrogen mediated mechanism for the CO2 reduction into CH4. The integration of a sorption column and the MEC biocathode showed a negligible effect in the overall biocathode CO2 removal, suggesting the control of the CO2 sorption by a chemical reaction through the alkalinity generation mechanism instead of the gas-liquid mass transfer.