Equivalent circuits studied by means of electrochemical tests employing different inoculum and simultaneous treatment during bioelectricity production in a single chamber-microbial fuel cell

Microbial fuel cells (MFC) have attracted the attention of scientists due to their capacity to improve electricity production and to employ wastewater as substrate. This duality results in a source of clean energy and degradation of the organic matter. The use of catalysts such as platinum make the implementation of these technologies difficult, therefore, it is a challenge to find economically feasible options and strategies carry out studies. Stream sediments (SS) and anaerobic granular sludge (AGS) were compared in a single chamber-MFC. Reactors constructed with Plexiglas contained carbon cloth cathode treated with polystyrene, graphite felt anode, and acetate as substrates. The voltage was measured with a digital multimeter, whereas power density and Coulombic efficiency were calculated based on Ohm's law. The electrochemistry impedance spectroscopy analysis was determined with an equivalent circuit model resistances. AGS-MFC produced 1.35 mW/m(2) and 30 mA/m(2), while SS-MFC produced 1.25 mW/m(2) and 20 mA/m(2) of power density and current density, respectively. AGS-MFC showed a 10% greater Coulombic efficiency compared to the one obtained from the SS-MFC. In this research, the effect of the inoculum on power density in an MFC was evaluated with the objective of finding sources of microorganisms with better capacities for electricity production and organic matter degradation. The equivalent circuit model showed that AGS-MFC obtained the lowest charge transfer resistance value and the highest constant phase elements values. AGS was the inoculum that showed the best performance in the MFC in terms of voltage and power density.

Automated summary

Microbial fuel cells (MFC) are a promising technology that can produce electricity and degrade organic matter using wastewater as a substrate. This study compared anaerobic granular sludge (AGS) and stream sediments (SS) as inoculum in single chamber-MFCs. AGS-MFC showed higher power density, current density, and Coulombic efficiency compared to SS-MFC. The electrochemistry impedance spectroscopy analysis revealed that AGS-MFC had lower charge transfer resistance and higher constant phase elements values. The findings suggest that AGS is a better inoculum for MFCs in terms of voltage and power density.