| With the intensification of the energy crisis,people have to find new clean energy,at this time,CW-MFC came into being.Under the catalysis of microorganisms,CW-MFC converts the chemical energy of organic matter in sewage into electrical energy,taking into account the dual effects of sewage treatment and biological power generation.In recent years,a lot of research has been carried out on it,especially the research on biological anodes,but there are few studies on cathodes,especially on biological cathodes.In CW-MFC,the cathode is an extremely important part,electrons and protons.And the electron acceptor completes the reduction reaction at the cathode,the cathode reaction is poor,and the electrochemical reaction is slow,resulting in poor electrical performance and water purification performance of the system.Therefore,this article makes an in-depth study on the modified cathode.In this paper,the experimental research and numerical simulation of the performance of the enhanced aerated cathode,microbial modified cathode,and chemically modified cathode to the cathode were carried out to discuss the best plan to improve the performance of the cathode.In this paper,four experimental columns are constructed.The CW-MFC constructed with no modified cathode is used as the experimental column one,which mainly serves as a control;the CW-MFC constructed with the aerated modified cathode is used as the experimental column two;the CW-MFC constructed with the trivalent iron modified cathode is used as Experimental column three;CW-MFC constructed by denitrifying bacteria modified cathode is used as experimental column four.By comparing experients to study the difference between its power generation performance and water purification performance to obtain the best performance of the modified cathode.Through research we have obtained a valuable conclusion:(1)In terms of electrical performance.The aeration modified cathode CW-MFC has the best performance,the shortest time to reach stability,and the maximum voltage generated reaches 483 m V,the maximum power density reached is 0.25W/m3,and the corresponding maximum current density is 1.53A/m3,its internal resistance is 160?;the performance of the control group without modified cathode CW-MFC is second,the time to achieve stability is 18 days,the maximum voltage generated is 200 m V,and the maximum power density reached is 0.0069W/m3,corresponding to The maximum current density is 0.21A/m3,and its internal resistance is 250?.The performance of the trivalent iron modified cathode CW-MFC is third.The time to reach stability is 31 days,the maximum voltage generated is 171 m V,and the maximum power density reached is 0.34W/m3,the corresponding maximum current density is 4.39A/m3,and its internal resistance is 50?;the denitrifying bacteria modified cathode CW-MFC has the worst performance,the generated voltage has been low,has been fluctuating,and there is no obvious stability At time,the maximum voltage is only 29 m V,the maximum power density reached is 0.00071W/m3,the corresponding maximum current density is 0.071A/m3,and its internal resistance is 170?;(2)Water purification: the aeration modified cathode CW-MFC has the best COD degradation characteristics,the removal rate of COD reaches 99%,and the remaining three experimental columns are not very different in COD removal;the aeration modified cathode CW-MFC also has Has the best NH-N removal characteristics,aeration modified cathode CW-MFC ammonia nitrogen removal rate> denitrifying bacteria modified cathode CW-MFC ammonia nitrogen removal rate> control group unmodified cathode CW-MFC ammonia nitrogen removal rate> trivalent Iron-modified cathode CW-MFC ammonia nitrogen removal rate,stable maximum removal rates were 98.8%,94.4%,86.6%,83.4% respectively.The denitrifying bacteria modified cathode CW-MFC has the best denitrification characteristics,The removal rate of NO-N is the highest,reaching 87.8%,followed by the unmodified cathode CW-MFC,the removal rate of NO-N is 78.7%,and the removal rate of the trivalent iron modified cathode CW-MFC is 78.0%,The worst is the aeration modified cathode CW-MFC,basically no denitrification denitrification has occurred,the content of NO-N not only did not decrease,but increased,the removal rate was-32.6%;Since the experimental process is to combine the anode and the cathode into a battery,as a whole,the performance of the cathode itself is not tested separately.For this reason,the cathode is numerically simulated.The conclusions of the simulation are as follows:(1)Power generation performance.When the inlet COD concentration is 150mg/L,250mg/L,350mg/L,the maximum output voltage is 344.23 m V,354.57 m V,364.33 m V.It can be found that the higher the inlet COD concentration,the greater the maximum voltage.And through analysis,it is found that the inlet COD concentration affects the anode biofilm inlet COD concentration,which further affects the electrical performance of the CW-MFC system;(2)Cathodic polarization characteristics.A?When the inlet COD concentration is 150 mg/L,250 mg/L,and 350 mg/L,the maximum potentials that the cathode can reach are 460.0 m V.When the current density is small,the potential difference of different COD concentrations is not large,and the factor limiting the reduction reaction of the cathode is the number of electrons;when the current density is large,the potential difference of different COD concentrations is large,and the limiting factor of the reduction reaction is the concentration of H+.B?When the water retention time is 1 day,2 days,and 3 days,the maximum potential that the cathode can reach is 246.0 m V.Shorten the water retention time,H + transmission rate is accelerated.However,excessively shortening the water retention time makes the system water flow rate fast,the contact time between the electricity-producing bacteria and the substrate is short and the activity is low,and the relatively large amount of organic matter flowing into the cathode is also not conducive to affecting electricity generation.The best water retention time is 2 days. |
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