Microbial Fuel Cells
Microbial fuel cells are the developing technology of the modern era
that is emerging as a green energy source (Logan et al. 2006; Venkata et al. 2008). This technology
exploits the catalytic abilities of microorganism to oxidize organic matter in
waste water and produce electrons (Logan et al. 2006). Thus electricity can be generated
simultaneously with waste water treatment (Liu et al. 2004).
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| Opened Microbial Fuel Cell (Irfan,2012) |
Microbial fuel cells have been under development stage for more than
100 years (Diane Greer,
Bio Cycle. 2007).In 1910 Prof. M.C Potter of Durham University put
forward the idea of production of E.M.F during fermentation of organic compound
by yeast ( Ieropoulos, 2005; Potter.
1912). The first known patent MFC however, dates back
to1967 (Yang et al. 2011).
Since then, several variants have been developed to optimize the efficiency of
MFC’s in order to get increased power density.
Although there is a wide range of materials and design configurations
depending on the MFC’s operational conditions have been used (Logan et al. 2006), basic
components of all MFC’s seem almost similar. Most commonly used and inexpensive
design configuration is the two chambers MFC with a traditional H shape (Logan et al. 2006). A typical MFC comprises (i) an air tight
chamber or chambers depending on configuration to ensure anaerobic conditions
at anode, (ii) anode and cathode electrodes, (iii) cation/proton exchange
membrane, (iv) conductor having a resistor or load.
Waste water flows in to anode chamber where bacteria take up organic
matter as substrate and oxidize it under anaerobic conditions. As a result
electrons are generated by bacteria that are captured at the negative terminal
i.e anode. Hence anode gets lower in potential.
If connected to positive terminal i.e cathode by means of a conductor
containing resistor or a load, the electrons at anode start moving towards
cathode. This flow of electrons causes current generation.
Oxidation of the substrate caused cation production. Cations/Protons such as H+
moves through cations exchange membrane and reaches cathode. As oxygen is
considered as the most favorable electron acceptor, oxygen supply is ensured in
the cathode chamber.
When H+ ions in the presence of electrons combine with Oxygen, water is
formed.
