Design of a Microbial Fuel Cell Used as a Biosensor of Pollution Emitted by Oxidized Organic Matter

Abstract

Microbial Fuel Cell (MFC) is an electrochemical device that converts polluted organic matter into electricity by using microorganisms as biocatalyst. Indeed, MFC can produce low renewable electric energy but preserve the environment. The aim of this study was to design a MFC-based biosensor using household wastes, in which anaerobes contained in the anolyte, are separated from the catholyte with a cation exchange membrane. This biosensor has been used to analyze biodegradable waste organic matter, where anaerobes act as biocatalyst for their oxidation and the transfer of electrons to the anode. Sodium acetate solution was used as substrate to obtain maximum energy. The MFC-based biosensor system was optimized by discharging it into an external circuit and phosphate solution buffer mixed with sodium chloride solution used as catholyte in the aerobic compartment. The anaerobic compartment was kept at room temperature to promote bacterial growth. It turned out that the MFC’s tension increased with the concentration of sodium acetate. It varied linearly with the substrate concentration, on a semi-logarithmic scale, thus making it possible to determine the minimum and maximum concentration thresholds. In addition, the electrochemical characterization by cyclic voltammetry of the bio-anode, revealed the oxidation current due to the degradation of the organic matter, which varied linearly with the scanning speed, highlighting the adsorption phenomenon on the surface of the porous electrode carbon felt. The MFC with a renewable aerobic bacterial source could therefore be used as a biosensor for on-line detection of pollution, in this case oxidized organic matter.