Research On The Kinetics Of Denitrification Of MFC By Cathodic Bacteria

The problem of nitrate pollution is a global environmental problem,and there are certain drawbacks to the traditional methods of disposal.Microbial fuel cell is an experimental device that uses microorganisms as a catalyst to decompose organic matter while converting the chemical energy in the fuel into electrical energy.Because of its wide range of fuel sources,mild reaction conditions,clean environment and no environmental pollution,it has attracted much attention of many scholars since it was discovered.With the nitrate solution as the electron acceptor,mixed flora from activated sludge and pure denitrifying flora were inoculated in the cathode chamber,and two kinds of biocathode microbial fuel cells named A-MFC and D-MFC were built.The denitrification and electricity generation properties of two kinds of cathode flora MFC under different NO₃^--N concentrations were studied.By analyzing the microbial community of cathode,the mechanism of nitrogen removal from two kinds of cathode flora MFC was discussed.The main results are as follows:?1?The performance of denitrification of two MFCs with different cathode flora under different NO₃^--N concentrations was studied.When the concentration of NO₃^--N is 25¹00 mg/L,the increase of concentration will promote the effect of denitrification of MFC by the two cathode flora,but at high concentrations,when the concentration of NO₃^--N is 100¹75 mgL,the higher the concentration of NO₃^--N,the more effective the denitrification of the two cathode flora MFCs.under different concentrations of NO₃^--N,A-MFC produced better electric performance than D-MFC,but D-MFC denitrification performance is better than A-MFC.Analysis results show Under different NO₃^--N concentrations,the two cathodic bacteria groups have the same change trend in denitrification and electricity production performance.?2?The selection of a suitable kinetic model to characterize the degradation of NO₃^--N in the MFC cathode of two cathode flora.The power function kinetic analysis results show that the first-order reaction is more suitable for characterizing the degradation of the cathode NO₃^--N in the two cathode flora MFCs at different concentrations of NO₃^--N.The Haldane model and Han-Levenspiel model were used to simulate the denitrification process of two kinds of cathode flora MFC at different NO₃^--N concentrations.The results showed that the Han-Levenspiel model fitted better.The semi saturation constant Ks of A-MFC is 60.02 mg/L higher than D-MFC?22.56 mg/L?,and the total inhibition concentration Sm is 183.13 mg/L below D-MFC?347.97 mg/L?,It shows that denitrifying flora have better affinity and greater tolerance to nitrate.?3?The cathode microbial community was analyzed at the initial stage of operation and the stable reaction period of two kinds of cathode flora MFC.The results of diversity analysis showed that the biodiversity of A-MFC was higher than that of D-MFC.The dominant strains of the two cathodic bacteria groups,MFC,were all deformable bacteria?Proteobacteria?in the period of stable operation,and the proportion of all the dominant bacteria was more than 50%.In the period of stable reaction,under the genus level,A-MFC dominant bacteria belonged to Azonexus,Zoogloea and Ignavibacterium,and D-MFC dominant bacteria belonged to Comamonas and Acidovorax,and all of them had denitrification.