Development of Bacterial Anode in Microbial Fuel Cell

Ouaknin Lea, Chemical Engineering, Ariel University, Kokhav Yaacov, Israel

Energy needs in the U.S and the world continue to increase, and in an effort to aid energy independence, research initiatives are focused on alternative, renewable and carbon neutral energy sources. Production of electrical energy using microorganisms through microbial fuel cells (MFC) is one such renewable and sustainable technology that is considered to be one of the most efficient and carbon neutral energy sources.

MFCs are fuel cells that are capable of converting chemical energy available in organic substrates into electrical energy using bacteria as a biocatalyst to oxidize the biodegradable substrates. The fact that bacteria can oxidize the substrates to produce electricity makes MFCs an ideal solution for the treatment of toxic materials and domestic energy production, wish can be used as a carbon source for the metabolism of bacteria. MFCs as a source of bio-energy production have accelerated the research worldwide and the technical aspects of MFCs have been reviewed extensively.

However the low power density and poor long-term stability limit its practical applications. Although a number of factors can affect a MFCs performance, the anode electrode associated with microbial inoculums has the greatest impact on its power density. The nature of the catalytic mechanism of a MFC anode involves not only a bio-catalytic but also an electro-catalytic process.

The choice of electrode material affects the performance of MFCs. Various materials have been investigated as electrodes to increase the performance and power output of the MFCs.

In this study we designed an effective MFC system that is comprised of a dual-glass chamber separated by a proton conductive membrane. We use platinum coated carbon cloth for the cathode chamber, because platinum coated electrodes are more efficient and superior in power production due to higher catalytic activity with oxygen than other electrodes.

The anode chamber contained a monoculture of exo-electrogenic bacteria: Geobacter sulfurreducens bacterial cells grown in acetate as a sole carbon source.

Anode chambers were constructed based on MFC carbon cloth, anode plasma treated, coated polylysine and not treated. We have reviewed the current density, the power density of the three types of MFC and also examine the potential of the anode, cathode and cell potential. We followed the live cells on the anode surface by spectrometric and biochemical methods. Compared to a carbon cloth anode, a polylysine-treated carbon cloth anode demonstrated an improvement of over 200 % in the current and a plasma-treated carbon cloth anode exhibited an improvement of more than 500%.

In conclusion, this study demonstrates that the use of a plasma- treated carbon cloth anode is the most effective and the most stable.