Study On Mechnism Of Electricity Generation In Microbial Fuel Cells

Microbial fuel cell(MFC)is a reactor which can change the chemical energy of the organic matter to electric energy with the microorganism to be the catalyst.Use the biomass to produce altermative energy.Electricigens is directly related to the electricity generation of the MFC.But there is theoretical deficiency for controling of MFC electricity generation because electricity-generating mechanism and process of the electricigens have not been clarified yet.The phenomenon of electricity-generating of MFC is directly related to the electrigens' extracellular electron transfer.To research the electricity-generating mechanism of the MFC,firstly,it is necessary to comparative analysis the electrigens' metabolic mode in the different culture condition.Secondly,there are many electrigens in the MFC,it's help for revelation the electricity-generating mechanism to isolate an efficiency electrogen strain.This research use a double-chambers MFC which is fed with glucose.From control different conditions to analysis the electrigens' electricity-generating mechanism.Then,isolated an electrogen strain from biofilm which in the anode of the MFC.And research the electricity-generating mechanism.The study results showed that:(1)When use the glucose to be a single substrate,It has many difference when the microorganism metabolic organic matter in access and the open circuit condition.In the access condition,the efficiency of microorganism metabolic organic matter is higher,so much the better of the substrate utilization.Microorganism can completely oxygenolysis organic matter from synergistic effect in the different strains.And get more cell growth.When processing circuit after the open circuit cycle,microorganism can futher oxygenolysis the small organic molecules which get from anaerobic fermentation.So the combine of electricity-generation respiration with the anaerobic fermentation is conducive to metabolic organic matter.(2)Use double-palte method separated an electricigens from anode biofilm of the MFC.To get the efficiency electrigens,add the ferric citrate to be a extracellular electron acceptor in the medium.The research get an efficiency electrigens in the end,identified by the biolog,the strain is Klebsiella oxytoca.(3)The results is show that the strain klebsiella oxytoca is of high electrochemical activity according to the cyclic voltammetry analysis.It can carry out extracellular electricigenic respiration in the environment with extracellular electron acceptor.The strain accomplished electricity generating respiration mainly through humus secreted as extracellular electron media through the three simensional fluorescence analysis of the strain's metabolite.The results of the ferric reducing experiments show that excessive ferric ion did not result in extra growth of the strain,and the ferric ion reduction rate of the strain was limited.(4)This research suggests that extracellular respiration is not the mainly respiration path way of the klebsiella oxytoca under anaerobic condition,but a subsidiary one as of the intracellular respiration in the presence of extracellular electron acceptor in the environment.Even there are enough extracellular electron acceptor in the environment,the strain's growth won't increase significantly.It is considered the strain does not obtain main growth energy from extracellular reduction,but from intracellular respiration.Only a small part of the electrons produced by oxidation of organic is used to reduce the extracellular electron acceptor.