In Situ Electrochemical Characterization of a Microbial Fuel Cell Biocathode Running on Wastewater

Abstract

The electrochemical features of microbial fuel cells’ biocathodes, running on wastewater, were evaluated by cyclic voltammetry. Ex situ and in situ electrochemical assays were performed and the redox processes associated with the presence of microorganisms and/or biofilms were attained. Different controls using sterile media (abiotic cathode microbial fuel cell) and membranes covering the electrodes were performed to evaluate the source of the electrochemistry response (surface biofilms vs. biotic electrolyte). The bacteria presence, in particular when biofilms are allowed to develop, was related with the enhanced active redox processes associated with an improved catalytic activity, namely for oxygen reduction, when compared with the results attained for an abiotic microbial fuel cell cathode. The microbial main composition was also attained and is in agreement with other reported studies. The current study aims contributing to the establishment of the advantages of using biocathodes rather than abiotic, whose conditions are frequently harder to control and to contribute to a better understanding of the bioelectrochemical processes occurring on the biotic chambers and the electrode surfaces.

Design and Optimization of Microbial Fuel Cells and Evaluation of a New Air-Breathing Cathode Based on Carbon Felt Modified with a Hydrogel—Ion Jelly®

“…The CV results confirm the direct redox activity on the anode electrode surface, resulting from the biotic environment on biofilm [54,61]. The oxidation peaks correspond to electron transfer by diverse microbial mechanisms responsible for the direct and indirect transfer of electrons to anode electrodes, in line with previous studies [54,60].…”

“…The maximum CD (174 mA/m 2 ) and DP (47 mW/m 2 ) in this MFC configuration were achieved with external resistance of 220 and 1000 Ω, respectively. However, the maximum DP in this MFC configuration was achieved for 1000 Ω, a value already used in the previous design condition experiments in this work, and it was identified for other authors as the best value [24,36,53,54]. Therefore, as these studies are performed only in batch operation mode, the resistance of 1000 Ω integrated into the external electric circuit was selected to evaluate the following design conditions and the MFC performance.…”