Research On Characteristics Of Electricity Generated By Shewanella Decolorationis S12 In Single Microbial Fuel Cell

With the industrial development and population expansion,the resources and environment of the world were seriously threatened.Utilizing resources economically,developing ways for waste reuse and establishing economically society were effective ways to solve resource shortage and lower environmental pollution.Microbial fuel cell was exactly a new technology that can degrade organic substrate and transform chemical energy into electrical energy.It made the wastewater, sludge and solid waste treatment become a process of biological energy production.A series of experiments to study on the characteristics of electricity generation by Shewanella decolorationis S12 was carried out in single microbial fuel cell(MFC).The experiment results are listed below:1.In order to determine the electrochemical activity of Shewanella decolorationis S12,anaerobic grown cells were scanned by the cyclic voltammograms(CV)in preliminary experiment.The results of CV showed that strain S12 displayed certain electrochemical activities and could be used as a catalyzer in microbial fuel cell(MFC)to producee lectricity.2.The strain S12 with the resistance of Rifampicin was verified to be high ability to reduce the azo dye and Fe(Ⅲ).Single membrane electrode assembly typed MFC(100 ml working volume)with 20 cm~2 cathode and anode surface was used to generate electricity.3.The electricity generation efficiencies of three kinds of electron donors,such as lactate,formate and pyruvate,were compared in MFC. The results showed that the optimum electron donor was lactate.The power densities would be improved with increasing the concentration of lactate.The maximum power density of 55.72 mW/m~2 was obtained when the concentration of lactate reached 20 mmol/L.However,when 30 mmol/L lactate was used,the power densities were not higher than those with 20 mmol/L lactate.Therefore,the optimum working concentration of lactate was 20 mmol/L.4.Inoculating with three different phase cells(exponential phase, stable phase and declining phase)in MFC to determine the optimal growth phase cells of S12 for the electricity generation.The results showed that the optimal growth phase of strain S12 for electricity generation was exponential phase.5.The change of pH and the consumption rate of sodium lactate were all coupled with the electricity generation.With the process of electricity generation going on,pH value in the system was increased gradually,as the concentration of H~+ gradually decreased and the concentration of Na~+ continually accumulated which should be balanced with OH~- The pH value increased from 6～7 to 7.5～8.5.High pH valve would inhibit the normal physiological metabolism of bacteria and affect the organic substrate utilization.Meanwhile,the electricity couldn't keep on generating.In order to resume the electricity,organic substrate should be added to the system to adjust the pH value and supply necessary nutrition for the normal metabolism of bacteria.6.Sodium lactate was analyzed quantitatively using HPLC.The results showed that the Consumption rate of sodium lactate coupled with the generation of electricity.