The effect of electrodes on the voltage generation of microbial fuel cell

Abstract

Microbial fuel cell (MFC) is a device that coverts the chemical energy contents of organic matter to electrical energy by the catalytic action of microorganisms. Cow dungs as organic substrates were used in three sets of dual chambered MFCs to study the effects of
electrodes on the open circuit voltage (OCV) generation of MFC. The anode and cathode compartments were connected using a proton
exchange membrane, 1 kg of the cow dung diluted with 500 ml of water was introduced in the anode compartment of each of the setups. The electrode configurations for set-up 1, 2 and 3 respectively were Carbon-Carbon(C-C), carbon-copper(C-Cu) and carbon- zinc(C-Zn). Samples  for microbial load count were collected every two days from the anode compartment of the MFC and analyzed using standard microbiological methods. The OCV of the three setups were measured daily for two weeks using a digital multimeter. The microbial load ranged from 4.2 × 10⁴ to 8.5 × 10⁴ CFU/ml for bacteria and 2.1 × 10² to 2.3 × 10³ CFU/ml for fungi. The range (average) of the OCV obtained from the set-ups were 0.06 to 0.72 V (0.42 V) for the C–C; 0.02 to 0.67 V (0.26 V) for C-Cu and 0.11 to 0.78 V (0.39 V) for the C-Zn. The OCV for the C-C electrode combination showed an increasing trend while the OCV of C-Cu and C-Zn showed decreasing trends with increasing number of days. The C-C electrode combination gave the best OCV.

Keywords: microbial fuel cell, open circuit voltage, electrodes, organic substrate