Effect Of Humic Acid And Concentration On Pure Culture Biocathodes Reducing Cr(Ⅵ) In Microbial Fuel Cells

Microbial fuel cells (MFCs) is a new technology that solves energy challenge and environmental pollution simultaneously in the past twenty years. It is extensively focused on because of the advantages of high efficiency, cleaning and low-cost. MFCs takes a bright future for heavy metal recycling, COD removal and dinitrification. Biocathode MFCs, which use microorganisms instead of other costly catalysts, are the future direction of MFCs. The clear electron transfer (ET) of biocathode microorganisms can enhance the effecience and decrease the cost of MFCs. Pure culture biocathode MFCs help clarify the ET of biocathode microorganisms, combining with the process of Cr(VI) reduction and electricity generation.In this study, a total of 14 pure cultures were isolated from mixed culture biocathode MFCs for Cr(VI) reduction using plating method. Power generation and Cr(VI) reduction rate were compared at different Cr(VI) concentrations and in the absence or presence of humic acid (HA). Pure cultures of 5 # exhibited a Cr(VI) reduction rate of 2.27±0.23 mg/(L·h), 14% higher than that with mixed cultures.95% of the charge distribution about species of 5 # was kown, but the current density was only 50% of mixed cultures. In view of electricity production, species of 1 # reached 29 mW/m,15% higher than that of mixed cultures whereas Cr(VI) reduction rates of the two were the same.50% of the charge distribution about species of 1 # was kown. The addition of HA had detrimental effects on Cr(VI) reduction rate, resulting in a remarkable decrease of 36% for species 3 #. In terms of electricity generation, the addition of HA had negligiable influences on all of these species. however, the coulombic efficiency of biocathode and biomass both decreased and the electron transfer processes changed in this system.