Enterobacter species specific microbial fuel cells show increased power generation with high coulombic efficiency

Microbial fuel cells (MFCs) convert chemical to electrical energy by oxidation of specific substrates using microorganisms generally anaerobic bacteria such as Enterobacter, Pseudomonas, E.coli, Clostridium etc. Optimization of MFCs has shown that to increase power input the internal resistance of the system has to be decreased. Comparison of power output in a proton exchange membrane containing MFC using Enterobacter cloacae or Enterobacter aerogens indicate Enterobacter spps. have higher voltage output with either sucrose or sodium acetate as substrate. Coulombic efficiency (CE) was compared between the two strains using a 15 days fed batch mode by replenishing the media with substrate every 3 days. Enterobacter aerogens and Enterobacter cloacae with sodium acetate as substrate gave a maximum voltage of 990 mV and 1100 mV respectively, the highest documented reading in voltage generation by MFCs. The results further demonstrate Enterobacter aerogens and Enterobacter cloacae have high coulombic efficiency of 89.99% and 91.4% respectively when using 0.4% sodium acetate as substrate. The maximum power obtained with a 100 Q resistance was 356.01 mW/cm² and 440 mW/cm² for Enterobacter aerogens and Enterobacter cloacae specific MFCs respectively. The results indicate that an increase in power generation and coulombic efficiency in MFCs is dependent not only on the exoelectrogenic microorganism but also on physical parameters such as the substrate in the anodic chamber and the formation of a biofilm on the anode electrode. The results indicate sodium acetate when used as a substrate has a higher power generating capacity and coulombic efficiency when compared to sucrose in a Enterobacter spp. specific dual chambered membrane MFC.