Study Of Microbial Fuel Cell Using Complex Microorganisms

Microbial fuel cells (MFCs) can transfer the chemical energy of organic substance into the electricity. With the development of this research, MFCs have produced the electricity from the organic substance of different kinds of actual wastewater. The development of this technology can not only reduce the pressure of energy crisis and'Greenhouse Effect'resulting from combustion of the traditional fuels, but also treat with the industrial and municipal wastewater. Therefore, MFCs is a novel technology without pollution, its'study and exploitation will become more and more attention-getting.In this thesis we adopt two-compartment MFC inoculated by complex microorganisms (CM-MFC) in the anodic compartment, investigate the performances of complex microorganisms to produce electricity, and the effect of operational conditions, such as, temperature, initial concentration of COD, stirring, pH in the anode, on the performances of CM-MFC; and then we further study the effect of the different pure bacteria constituting the complex microorganisms on the performances of CM-MFC. The results show CM-MFC can produce electricity from the artificial wastewater (AW), after several accumulations the output power of this system with complex microorganisms increases by 146%, and the electricity production mainly depends on the biofilm of complex microorganisms on the anode; the performances of the system are affected more by the concentration of COD and pH in the anode than other factors, and we obtained the maximum output power (149.17mW/m~2) in the acid condition。The experiments looking for the bacteria producing the redox medium prove the PSB and actinomycetes can produce some redox mediums to promote the electron transfer in the anodic compartment; lactobacillus is main bacteria producing electricity in the complex microorganisms, with them the system can generate maximum output power 109.21mW/m~2, which is 6.85-fold by actinomycetes, 7.93-fold by microzymes, and 13.86-fold by PSB, respectively.In order to identify the ability of CM-MFC to generate electricity from actual wastewater, we investigate the performances of CM-MFC using the Huarun beer wastewater (COD=579mg/l) and Haihe milk wastewater (COD=586mg/l) as fuels, and obtain the maximum output power of 112.22mW/m~2 and 34.93mW/m~2, so this system is applicable to use the actual wastewater as its fuels.Meanwhile, by CV and ESEM of biofilm of complex microorganisms and every pure bacterium, the results show that complex microorganisms is a electricity production system in which lactobacillus is main bacteria generating electricity, and PSB and actinomycetes can produce the redox mediums to complete electron transfer from bacteria to the anode. Based on this result, we analyze the mechanism of electron transfer in the anodic compartment of CM-MFC, and deduce that electron transfer in the CM-MFC is completed by two paths: membrane-associated components, nanowires and soluble redox mediums produced by bacteria.