Set up of a Microbial Fuel Cell for the Treatment of a Garden Compost Leachate: Impact of the External Polarizing Electric Resistance Upon the Chemical Oxygen Demand Removal

Abstract

Microbial fuel cells (MFCs) are new and growing renewable energy devices. They transform chemical products into electricity with the help of microorganisms (enzymes, bacteria, microbes, etc.) acting as biocatalysts. They are nowadays displaying technological development since they concomitant simultaneously the wastewater treatment and the electric power generation. These two novelties incite researchers in the field, the utilization of this promising technology. As a matter of fact, a bioelectrochemical fuel cell has been elaborated and set up for garden compost leachate treatment. Following a previous study on the microbial anode formed from wastewater under the application of an electric potential either positive or negative by using chronoamperometry. In this work, we propose the simple method of connecting the two electrodes (anode and cathode) by electrical resistance, to flow a current. The impact of the polarizing electric load on the achievement of the MFC has therefore been studied. Moreover, the chemical oxygen demand (COD) removal for the MFC running for 7 days has been also investigated. It decreased and showed simultaneously an increase in the cell voltage. Thus, the effects of the external load on the current and power generation, as well as on pollutant removal, have been studied by modifying each time the external load. The external polarizing resistance (EPR) was increased from 1 to 10 kΩ, to assess the pollutant decay of the organic matter contained in the wastes. As a result of this, the voltage was increased, whilst the current was decreased, with increasing values of the EPR. The results have been discussed with respect to the type and the predominant microorganisms (electrogenic/fermentative) being involved during the generation of the electric current. This new technology is very promising for converting waste into electricity by offering a way to clean up the polluted environment.