Study On The Factors Influencing The Treatment Of Landfill Leachate By Single-chamber Air-cathode Microbial Fuel Cells

Microbial Fuel Cells?MFCs?,as a new type of waste water treatment technology,have the ability to convert the chemical energy of the organic pollutants into electric energy from various types of waste water,and at the same time,the waste water can be effectively treated.Compared with the traditional waste water treatment technology,MFCs is more in line with the demand of"clean production".The research on the theory and practicability of this technology can provide a driving force for the advancement of waste water treatment technology in China.In this paper,single-chamber membraneless air-cathode microbial fuel cells is taken as the research object.The change of landfill leachate integral in MFCs anode substrate and the optimization of MFCs air cathode fabrication method were studied.Under different operating conditions,the power generation performance of MFCs and the treatment effect of landfill leachate from anode substrate were investigated,and the influencing factors in the treatment of landfill leachate by single-chamber membraneless air-cathode microbial fuel cells were analyzed.Firstly,single-chamber membraneless air-cathode microbial fuel cells were constructed with landfill leachate as anode substrate.Four groups of MFCs with 20%,40%,60%and 80%landfill leachate integral fraction in anode substrates were set up to study the effect of landfill leachate integral fraction on the electricity generation performance of MFCs reactor and the change of pH value between the liquid inlet and the liquid outlet of anode substrates.Among the four groups of MFCs reactors,2#reactor has the best battery performance,the largest stable output voltage,and 4#reactor has the longest stable output voltage duration.The order of magnitude of open-circuit voltage?OCV?is OCV2>OCV3>OCV4>OCV1,and the polarization curves are nearly linear decreasing.With the increase of the integral fraction of landfill leachate,the maximum power density of batteries increases rapidly at first and then decreases gradually.The maximum power density of 2#reactor is the highest and that of 1#reactor is the lowest.The internal resistance of batteries decreases rapidly at first and then rises gradually.The internal resistance of 2#reactor is the lowest and that of1#reactor is the highest.For the Coulomb efficiency?CE?of four groups of MFCs reactors,the CE of 4#reactor is slightly higher than that of 1#,2#,3#reactor.CE did not change much among the groups,and as the volume fraction of landfill leachate in the anode substrate increases,CE decreases first and then increases.The pH values of the liquid outlet of the anode substrates in the four groups of MFCs reactor increased slightly compared with those in the the liquid inlet.The pH values of the liquid inlet and the liquid outlet of the anode substrates in the 2#reactor were relatively different.Among the other three groups of reactors,the difference of pH value between the liquid inlet and the liquid outlet of anode substrate in 1#reactor is slightly smaller than that in 3#and 4#reactor.Furthermore,this paper studies the effect of landfill leachate integral on the treatment effect of MFCs reactor on landfill leachate.Among the four groups of MFCs reactors,2#reactor has the highest COD removal and COD removal rate in the anode substrate.1#reactor has the lowest COD removal rate in the anode substrate,but the COD removal rate is not the lowest.The COD removal of 3#and 4#reactors are not significantly different,but the COD removal rates decreased with the increase of the landfill leachate fraction in the anode substrate of batteries.The removal of ammonia nitrogen in leachate from anode substrate landfill by four MFCs reactors were 159.864,347.425,509.245 and 695.332 mg L^-1,respectively.The removal rates were 79.93%,86.86%,84.87%and 86.92%,respectively.The removal efficiency of ammonia nitrogen in the leachate of anode substrate landfill is better and there is no significant difference among the reactor groups.After that,a preliminary optimization of the air cathode was made on the basis of the traditional air cathode making method.In this paper,the carbon black-PTFE mixture is used to replace the single PTFE emulsion used in the production of the traditional air cathode.And the sintering process of air cathode diffusion layer and catalytic layer was improved to simplify the manufacturing process of air cathode.Therefore,a new type of air cathode is established,which improves the conductivity and gas conductivity of the diffusion layer and reduces the cost of the diffusion layer and the catalytic layer on the basis of maintaining the original mechanical strength and sealing of the anode chamber.The MFCs reactor with new air cathode and the MFCs reactor with traditional air cathode were compared and analyzed.The performance of MFCs reactor with new air cathode is better than that of MFCs reactor with traditional air cathode in terms of stable output voltage,maximum power density,current density and internal resistance.The power generation performance of MFCs reactor has been improved.And at the same time,the shortcomings of the new air cathode are analyzed and discussed in this paper.