Comparative Study on Performance of Bacterio-algal Fuel Cell with and without Biofilm

Microbial Fuel Cells (MFCs) convert chemical energy stored in organic carbon sources to electricity using exo-electrogens. In Bacterio-algal Fuel Cell (BAFC), algae are used in the cathode chamber to assimilate CO2 produced in anode chamber and produce oxygen required for cathode reaction. The present article focuses on the performance of a batch type BAFC using lactic acid as substrate and clay as PEM instead of expensive Nafion. Exoelectrogen, Shewanella putrefaciens MTCC 8104 and cyanobacterium, Leptolyngbya subtilis JUCHE1 have been used in the anode and cathode chambers respectively. The volumes of the anode and cathode chambers are 150mL and 700mL respectively and carbon cloth has been used as anode and cathode material. The BAFC has been run for 120h with the concentration of substrate being 3g/L with and without biofilm of Shewanella putrefaciens MTCC 8104. The maximum current of 37 μ A and coulombic efficiency of 5.91% have been obtained for the BAFC, run without biofilm, using the substrate concentration of 3g/L. Using biofilm, the peak operating current and coulombic efficiency reach the value of 230 μ A and 33.06% respectively. The cyclic voltammograms of biofilm systems also show efficient charge transfer as compared to that using suspended culture in the anode chamber. This study introduces the novel approach for applying biofilm alongside the usage of algal strain on cathode side of MFC. Results successfully demonstrate the effectiveness of the proposed strategy based on improved electron transfer and power output, paving way for further upgradation of the system based on mode and scaling up.