Microbial fuel cells using volatile organic acid for electrical current generation

Abstract

The Microbial fuel cells (MFCs) were operated using pure culture and mixed culture. Shewanella putrefaciens was previously used in the mediator-less microbial fuel cell (MFC) but with low efficiency. Lactate was used as the electron donor in the anode compartment. Carbon paper, carbon fibers and carbon felt were used for both an anode and cathode site according to circumstances. Type I having ferricyanide as a mediator of cathode generated power density 5.25 mW/㎡ and current density 40.30 mA/㎡. Type I MFC plus methylene blue in the anode compartment, Type II was evaluated maximum current density 154.8 mA/㎡ maximum power density 48.1 mW/㎡. These power densities and current density are higher than those without methylene blue for MFCs with S. putrefaciens CN32. Power generation using single-compartment MFC was maximum current density 254.8 mA/㎡ and maximum power density 81.5 mW/㎡. Power generation of MFC using HEROS sample without installation adding oxygen was evaluated as maximum power density of 141mW/㎡. However MFC inoculated with HEROS sample supplying air as 0.5 vvm velocity showed 488 mW/㎡ of maximum power density and adding 2M $H_2O_2$ yielded maximum power density as 560 mW/㎡. After 4days operation, the MFC generated maximum power density 1,676 mW/㎡. PCR-DGGE analysis was employed to investigate the microbial community. Different microbial profiles were observed with biofilm samples obtained from HEROS sample and heated HEROS sample that were used for different primers such as Bacteria and Archaea. Many bands were related to bacteria indicating that many novel bacteria were enriched in the oligotrophic MFCs. In the biofilm samples, And nucleotide sequences HEROS sample used Archaeal primer were affiliated with Methanosaeta concilii, Uncultured Methanosaeta sp. clone M1，Uncultured Methanosaeta sp. clone KB-1 2, Cryptococcus neoformans var. neoformans JEC21, Methanoculleus chikugoensis and Methanoculleus palmolei. However, profiles of heated HEROS sample...