Characteristics Of Microbial Fuel Cell For Perchlorate Reduction And Regulative Mechanisms With Redox Mediators

Perchlorate is a kind of persistent and toxic substance.The illegal emissions in the processes of its use and production have brought serious environmental problems.As a new biological technology,microbial fuel cell（MFC）can produce electricity from wastewater treatment and becomes a research focus of environmental energy technology.Hence,sodium perchlorate was selected as a model pollutant and was treated by MFC in this thesis.After successful startup,the operating characteristics of MFC was studied.The effects of different electron acceptors and redox mediators on MFC performance were explored.The electron transfer mechanisms of the redox mediators were disscussed.The performance of the MFC was stable after continuous operation（140 h）.In the stable stage,the best perchlorate concentration（150 mg·L-1 initial perchlorate concentration）and the best carbon source（sodium acetate）were selected.Different kinds and concentrations of electron acceptors had different effects on MFC performance.Perchlorate reduction had been significant suppressed with the existence of nitrate and chlorate.The voltages were higher with different concentrations of nitrate were reduced and the voltages were lower with different concentrations of chlorate were reduced.When nitrate and chlorate were depleted,the voltages of MFC generated were returned to 58 mV because of the perchlorate reduction.Perchlorate reduction had been significant suppressed with sulfate addition.The thermodynamics analysis showed that nitrate reduction,chlorate reduction and perchlorate reduction needed to fight for electrons.And the electrochemical analysis showed that nitrate reduction and chlorate reduction reduced the electron transfer resistance and increased the activity of anode.The respiratory chain of anode in MFC was studied by adding CuCl₂,NaN₃,coumarin,rotenone,quinacrine dihydrochloride（QDH）,N,N’-dicyclohexylcarbodiimide（DCCD）,carbonyl cyanide 3-chlorophenylhydrazon（CCCP）,capsaicin to the anode cultures of MFC,respectively.The results showed that NADH dehydrogenase,NADH-Q reductase,methylnaphthoquinone,Fe-S protein,ATP synthetase,FAD reductase were important parts of the respiratory chain.The performance of MFC was enhanced by adding different concentrations of resazurin,neutral red,methylene blue,potassium ferricyanide（FeCN）and anthraquinone-2,6-disulfonic acid sodium salt（AQDS）.Resazurin was used as the redox mediator for exploring the regulative mechanism of redox mediators.The presence ofresazurin increased the content of humic acid and decreased the content of polysaccharide.The increased content of humic acid and the decreased content of polysaccharide reduced the electron transfer resistance.The accelerating sites of resazurin were NADH reductase,NADH-Q reductase and methylnaphthalene.