Electrochemical characterization of anodic biofilms enriched with glucose and acetate in single-chamber microbial fuel cells

This study used a simple and efficient electrochemical technique, cyclic voltammogram (CV), to quantitatively measure the electron transfer capability of anodic biofilms enriched with acetate and glucose in single-chamber microbial fuel cells (MFCs). Two pairs of distinct redox peaks were observed by CV measurements in both biofilms, identical to the CV features of a pure Geobacter strain. The CVs also revealed a higher density of electroactive species in the acetate-enriched biofilm than that in the glucose-enriched biofilm. Based on the scan rate analysis, the apparent electron transfer rate constants (k(app)) in the acetate-enriched biofilm and glucose-enriched biofilm were determined to be 0.82 and 0.15s(-1), respectively, which supported the higher power output of the MFC fed with acetate. Meanwhile, the pH dependence of the biofilms was studied by monitoring the changes of the biofilm redox peak currents and potentials. It is concluded that redox reaction of the electrochemical active species in biofilms is pH dependent, and both electrons and protons are involved in the redox reactions.