Synergistic Removal Process And Mechanism Of VOCs And NO_x From Incineration Flue Gas By Biological Degradation Integrated System

At present,air pollution in China has evolved into a compound pollution with fine particulate matter(PM2.5)and ozone(O3)as the primary pollutants.Volatile organic compounds(V OCs)and NOx are important precursors of the formation of O3 and PM2.5.Waste incineration will produce a large amount of NOx and VOCs with foul odor.Therefore,the effective control of VOCs and NOx in waste incineration flue gas is of great significance to the improvement of atmospheric environmental quality at the present stage.Microbial purification technology has the characteristics of economic green and wide application range.In this study,waste incineration flue gas was taken as the treatment object.Combined with the principle of BioTrickling Filter(BTF)to purify VOCs and Chemical Absorption-Biological Reduction(CABR)to treat NO.,a microbial purification collection system was established.The synergistic removal of VOCs and NOx was realized,and the synergistic degradation mechanism and interaction mechanism of pollutants were explored.The main research results were as follows:According to the requirements of VOCs biological purification and biological denitration,the corresponding microbial strains were domesticated,and the new bacterial flora structure was constructed through the doping of bacterial strains and the control of domestication conditions,so that the bacterial flora could simultaneously degrade multiple pollutants and broaden the biological diversity of the bacterial flora.A set of Absorption,biodegradation and Biotrickling filter(ABR-BTF)was built,and the combined operation structure was optimized from the two operating structures of coupling and combination.Simultaneous removal of VOCs and NOx with toluene as the main model substance was realized.When the simulated flue gas containing 150 mg·m-3 toluene and 400 mg·m-3 NO passed through the system with 30 s residence time,the removal efficiency of the two pollutants reached 85%and 90%,respectively.In addition,the loss rate of NO complex absorber was reduced by 85%compared with that of the single CABR system under the same conditions.After many reaction processes in the simulated flue gas system,the simultaneous removal of toluene and NOx was finally completed.During the operation of ABR-BTF integrated system,NO was absorbed by the simulated flue gas through the gas-liquid contact process of ABR plate tower,and toluene was preliminarily degraded to alcohol-ketone organic compounds and CO2.The liquid phase at the exit of the plate column enters the ABR bioreactor,and the NO is reduced to N2 by microbial denitrification,at the same time the organic matter in the liquid phase is completely degraded.The organic matter in the exhaled gas phase of the plate column enters the BTF packed column and is further degraded.In this study,we found a variety of bacterial genera in the biome of the integrated system that had not been reported in the field of biological denitration and VOCs biological removal,and speculated their synergistic mechanism in the system according to the known characteristics of bacterial genera and experimental results.Among them,intertrophic microorganisms such as Candidatus Cloacamonas and Syntrophomonas produced electron donor H2 and consumed dissolved oxygen while degrading VOCs,which promoted the biological reduction reaction and reduced the loss of complexing absorbent.There are Tisierella and Desulfitobacterium that can reduce sulfite to S2-,so that part of the complexing absorbent is lost in the form of FeS and can be re-entered into the circulation system through redox reaction with Fe(III).Besides,Mycobacterium,Truepera and other highly efficient bacteria targeted at the degradation of aromatic hydrocarbons make the system have a good deodorization ability to the flue gas containing phenol,xylene and other malodorous organic compounds with low smell threshold.