Nitrate Removal And Electron Transfer Mechanism Research In Microbial Fuel Cell

This article introduces that the basic principles of microbial fuel cells and research progress in domestic and foreign. On this basis, factors about cathode system were studied in a dual-chamber MFC on the influence of the nitrate removal rate and performance of MFC electricity generation. These factors are MFC cathode microorganisms, the initial nitrate concentration in the cathode, existence of ammonia and inorganic carbon in the cathode solution, and when the middle of the dividers are the salt brige and cation exchange membrane, the voltage output, internal resistance and the maximum power density are compared in the MFC system. In addition, it conducts the preliminary study on the mechanism of electron transfer between microorganisms and electrode by cyclic voltammetry. The results are as follows:The dual-chamber microbial fuel cells, inoculated with activated sludge and denitrifying bacteria can generate electricity, simultaneously, denitrify the nitrate pollutants, and the anode COD effectively. In addition, the SEM images indicate that differences exist in surface morphology of carbon cloth not only in A-MFC and D-MFC cathode, but greatly in the anode and cathode.The mass transfer rate of the cathode solution has a certain influence on the denitrification and the performance of the electricity generation of MFC. The faster mass transfer speed, namely the higher nitrate initial concentration, the faster denitrification rate. It helps to improve the performance of the electricity generation in MFC. Sodium bicarbonate can improve the denitrification rate, but degrade the performance of the electricity generation of MFC. Ammonia has inhibitory effects on the denitrification and the performance of electricity generation of MFC.The internal resistance of MFC with salt bridge is much larger than that with cation membrane. The maximum output voltage of MFC with salt bridge is lower, the maximum power density decrease, and the time of stabilization output voltage is about300hours less than that with cation membrane.The biomass on the anode carbon cloth is proportional to the voltage in the MFC. The microorganisms, grew on the electrode surface, have an important role for electricity generation in the MFC, rather than microorganisms suspended in solution. The bacteria on the anode biofilm conduct catalytic oxidation, and catalytic reduction reaction on the cathode biofilm. In addition, the transmission mechanism of the electron shuttle truly exists in the MFC system.