Electrochemical behavior of a multi modular microbial fuel cell operated using cow dung enriched inoculum: Enhanced energy recovery using electrochemical optimization

Abstract

A litre-scale multi-modular microbial fuel cell was operated using exo-electrogenic inoculum enriched from cow-dung for 45 days in batch mode, under three different circuit connections, individual, combined and series; and electrochemical analyses was performed using an electrochemical analyzer in a two-electrode mode. Among the three circuits, maximum power output was observed in case of the individual circuit followed by combined and series. From the LSV data, a maximum power density of 1480 mW m-2 was derived at the current density of 2820 mA m−2 for individual circuit connection (module 2), while the average power density and current density for all the six modules was estimated to be 1260 mW/m2 and 2590 mA/m2, respectively. The CV curves obtained for MFC under operation demonstrated the appearance of redox peak current of 1.7 mA for module 2 and an average on 1.1 mA for all the six modules. Rin as derived from the EIS analysis of the MFC was 84.2 Ω, which was minimum in case of individual connection. Additionally, 67% COD removal and 12.4% columbic efficiency was observed for the MFC under given set of operating conditions. The electrochemical investigations of the MM-MFC suggested that the electrochemical metabolic rate was highest in the individual circuit while internal resistance was minimum, resulting in maximum power generation. The power density obtained in the current investigation is highest (1480 mW/m2) than that reported in literature yet, for a MFC of similar scale and design. Moreover, the study for the first-time reports detailed and extensive electrochemical analysis of MFC.