GENERATION OF ELECTRIC POTENTIAL DIFFERENCE ACROSS THE ELECTRODES OF THE MICROBIAL FUEL CELL IN THE ANAEROBIC OXIDATION OF SUBSTRATES BY MICROBIAL ASSOCIATIONS

Abstract

From natural and anthropogenic sources several microbial associations were obtained. All of associations, grow well on glucose and significantly worse on acetate. It is observed 80—95% glucose consumption during 3—5 days growth. The substrates oxidation by cultures generates an electric potential difference between the anode and cathode electrodes of the microbial fuel cell (MFE). The value of the potential difference depends on the nature of the association and the substrate and reaches 400—500 mV. Potential difference generation accompanied by a shift in the negative region of the medium redox potential (Eh) to –(300—400) mV. This indicates H2 evolution by association cultures during carbohydrates oxidation. Artificial redox mediators such as tetramethyl-p-phenilen-diamine, phenasine methosulphate and benzyl viologen able to increase up to 15% difference in electrical potential across the electrodes MFE. It is ssumed that the increase in the potential difference across the electrodes, induced redox mediators due to their direct involvement in the transfer of electrons from the bacteria in the incubation medium into MFE anode electrode. Direct measurement of current and potential difference on electrodes in a mode of “short circuit” shows that the internal resistance of MFE is equal to 1 Kohm, and power reaches 5 microwatt. Undoubtedly it testifies to the low efficiency developed by MFE.