Comparative Study of Various Substrates and Microorganisms in a Laboratory Designed Microbial Fuel Cell

Abstract

Bio-electrochemical systems have recently emerged as an exciting technology to generate the electricity that is considered as the ladder for the development. The most desirable type of bio-electrochemical system is the microbial fuel cell (MFC), in which power could be generated from electron donors that are present in the form of organic matter, substrates and effluents from the industry. A microbial fuel cell consists of an anode, a cathode and proton exchange membrane (PEM, or more precisely a cation exchange membrane (CEM)). The electrons available through the metabolism of the substrates i. e. electron donors, by microorganisms are transferred to the anode of the fuel cell and then to the cathode through the external circuit, where they reduce the oxidant, consuming protons available from the anode through the membrane. A simple microbial fuel cell was designed in laboratory, using four different substrates (glucose, sucrose, starch and sodium acetate) along with the addition of microbial cultures of bacteria, (Escherichia coli, Bacillus subtilis) and fungi (Saccharomyces cerevisiae), at the bottom of the anode chamber. Electron transport system started in the anode chamber due to microbial activity which was accelerated and availed by the use of the mediator, methylene blue and the transport of protons started from anode to cathode through the membrane that was agar salt bridge in this study. The electricity generated was measured by multimeter device and recorded in milliamperes (mA), which was higher in case of bacteria and E.coli being the most potent generator. Glucose as the substrate generated higher voltage and current in comparison to the other three organic substrates viz. sucrose, starch and acetate.