The Performance Of Electricity Produce And Pollutant Degradation Of Modified Electrode And Multi-electrode Microbial Fuel Cell

A microbial fuel cell (MFC) is a promising device which can convert the chemical energy containing in organic wastewater into electrical energy. In this study, a no membrane up-flow air cathode microbial fuel cell was build, in which carbon rod was as anode and carbon felt was as cathode, while landfill leachate was as the fuel. Air cathode electrodes was obtained by chemically modified carbon felt with HNO3 adsorbing the ferric nitrate/activated carbon powder catalyst (Fe/C catalyst) which was obtained by impregnation. The performance of carbon felt anode, modified carbon felt anode and a graphite rod anode was compared in the best condition of modified carbon felt cathode. Finally, the original device was improved, build the multi-electrode membrane-air cathode MFC reactor with the optimal electrode, analysis the performance of producing electricity.Effect of carbon felt oxidized time by HNO3 on the Fe/C catalyst dosage adsorbed on modified carbon felt, the conductivity of modified carbon felt air cathode, and electricity generation performance and the discharge capacity of MFC were investigated. And the performance of the optimal modification time Fe/C catalyst carbon felt air cathode MFC treating landfill leachate and the long-run stability of MFC were evaluated by steady discharge and cyclic voltammetry tests. Results showed that with the extension of carbon felt oxidized time by HNO3, adsorption amount of Fe/C catalyst by modified carbon felt increased, the conductivity of the modified carbon felt air cathode increased gradually and to be stable. The electricity generation performance of modified carbon felt air cathode MFC enhance gradually, but reduce after achieving the peak value with chemical modification time. Excessive catalyst that the modified carbon felt adsorbed may increases internal resistance and reduces the power density of MFC. The best time of HNO3 chemical dioxide carbon felt is 6h, the maximum output power density was 6265.67mW·m-3,2,4 times higher than the unmodified one. The internal resistance of the cell was 358?. The cyclic voltammetry further evidenced the best modified time is 6h and obtained the maximum discharge capacity of MFC with stable operation. The maximum removal of COD and ammonia in the best modified conditions was 91.2% and 46.77%, respectively.By comparing the electrical production of different materials anode showed that the greater the porosity of the anode material, the greater the adsorption of microorganisms and the greater the resulting open circuit voltage.The potential of carbon felt anode electrode was higher than the carbon rod one, the potential of modified with carbon felt anode was higher than the unmodified carbon felt one. Although the carbon felt anode adsorbed more microorganisms, its output power and coulomb efficiency were lower than carbon rod anode,showed that the microbial of anode attachment did not completely determined the output power of MFC, different materials of anode had different capacities of electron transfer. The cyclic voltammetry tests found that three electrodes microbial had certain activity. The electrochemical activity was the strongest when the anode was carbon rod. The carbon rod anode electrode was reversible and the unmodified carbon felt one was part of the reversible and the modified carbon felt one was irreversible process. The factors of affecting MFC long-running of output power reduction were the cathode carbon felt trapped sludge and cathode catalyst losses.The operating parameter of multi-electrode air cathode MFC was studied. The results showed that the power outputs of two-tier and three-tier air cathode MFC was increased with the increasing of hydraulic retention time and the influent organic load. When the hydraulic retention time was 8.5h and the influent COD concentration was 2417.82mg/L, the more increasing cannot change the electricity production of MFC. With the hydraulic retention time and the influent organic load increased, the removal rate of COD first increased and then decreased, the removal rate of NH4+-N gradually increased and then remained stable.