Study on Generation of Bioelectricity Using Potassium Ferricyanide Electron Acceptor in Microbial Fuel Cell

摘要

The capability of simultaneously generating bioelectricity and treating piggery wastewater using microbial fuel cell (MFC) with indigenous exoelectrogens was demonstrated. Three units of H – type MFCs were constructed using 0.1M potassium ferricynide (Ksub3/sub[Fe(CN)sub6/sub]) as catholyte and carbon – carbon (CC), carbon – copper (CCu) and copper – copper (CuCu) electrodes of surface area 0.0071msup2/sup each. The BOD and COD of the test piggery wastewater were 420mg/L and 1057mg/L respectively. While coulombic efficiency (CE) of the MFCs after 25 days were 76%, 72% and 5.10%, COD removal were 83%, 48% and 49% for CC, CCu and CuCu respectively. Highest voltage recorded were 752.4mV, 1027mV and 625.2mV across CC, CCu and CuCu respectively. Generation of voltage proportionally decreased with decreasing external resistors. Power density which increased with decreasing external resistance across each MFC until 200? beyond which decrease became evident, peaked at 60.94mW/msup2/sup (92.6mA/msup2/sup), 39.94mW/msup2/sup (75.0mA/msup2/sup) and 14.21mW/msup2/sup (44.70mA/msup2/sup) across Rsubext/sub = 1000? for CC, CCu and CuCu respectively. This depicts that carbon used as both cathode and anode produced more bioelectricity than other combinations. Bacteria isolated from the surface of anodes include, iLactobacillus /ispp., iCorynebacterium /ispp., iStreptococcus/i spp., iProteus mirabilis, Enterobacter /ispp., iEscherichia coli, Pseudomonas /ispp., iBacillus/i spp., iAeromonas/i spp., iMicrococus luteus, Corynebacterium /ispp. and iSalmonella /ispp. Plasmid profile of the bacteria isolates in the original wastewater sample revealed that Lactobacillus spp., iProteus mirabilis, Escherichia coli, Pseudomonas /ispp., iBacillus /ispp., and iAeromonas /ispp had plasmids. These findings show that with better designs and optimization, the performance of the MFCs can be enhanced.