Study On Construction Of Enhanced Biological Trickling Filter With High Efficient BTEX Degradation Bacteria And Its Toluene Treatment Performance

Benzene,Toluene,Ethylbenzene,and Xylene(BTEX)are frequently detected in pesticides,petrochemicals and other contaminated soils and groundwater.The exhaust gas produced by in-situ remediation has high moisture content,large fluctuations,and activated carbon adsorption Technology is difficult to remove.This paper aims to screen biomaterials that can degrade benzene series,build biofilters,and provide technical support for soil,groundwater and terminal remediation.In this study,we obtained benzene series contaminated soil from pesticide factories,obtained high-efficiency degrading bacteria through enrichment and domestication in serum bottles,and obtained high-efficiency benzene series degrading bacteria from the bacterial colony.First of all,the degradation characteristics of the flora and single bacteria were studied by GC,LC-Q-TOF and other methods,clarified the kinetics of degradation of benzene series,and revealed the metabolic pathways of benzene series;and analyzed by means of high-throughput sequencing.The community structure of the flora and the functional genes of the benzene series metabolism in the flora;on this basis,a biological trickling filter was built to inoculate a single bacteria to purify the benzene series waste gas.The main results are as follows:(1)Benzene-degrading bacteria group H1 under the optimal conditions of 28?,pH 8.0 and adding 100 mg/L yeast powder,the bacteria group completely degrades 100 mg/L of benzene within 6 hours,and completely degrades within 30 hours 30 mg/L mixture of benzene,toluene and ethylbenzene.Phenol and catechol can be detected as intermediate products of benzene degradation.the P3 subunit of the phenol monooxygenase gene was amplified by PCR(GenBank accession number:MW388722).High-throughput sequencing results showed that the flora mainly contains Cupriavidus,Arthrobacter,Corynebacterium,and other bacterial genera,among which Cupriavidus is the dominant bacteria,and the degrading flora has a stable structure.(2)Three strains of high-efficiency degrading bacteria were screened from the benzene-degrading bacteria group.Among them,the benzene-degrading bacteria Corynebacterium sp.AL-5 can degrade benzene and toluene.At 28?,pH 8.0,and 100 mg/L yeast added Under powder conditions,100 mg/L of benzene can be completely degraded within 10 hours,and benzene can be degraded through the metabolic pathways of phenol and catechol.Achromobacter sp.ED-2 and Diaphorobacter sp.ED-3 can degrade all BTEX substances.ED-2 and ED-3 can completely degrade 50 mg/L of toluene and ethylbenzene within 56 hours,which is comparable to AL-5.Compared with,although the degradation rate is slightly lower,its degradation substrates are more extensive.(3)The above-mentioned strains and activated sludge are mixed and added to the biological trickling filter to circulate the membrane.When the toluene concentration in the trickling filter is about 600 mg/m3,after 21 days of membrane formation,the amount of biofilm on the ceramsite and activated carbon is 114.1 g/kg,the toluene removal rate reached 94%at this time.When the empty tower residence time is 68 s,the toluene removal rate stabilizes above 94%.When the empty tower residence time is changed to 17 s,the toluene removal rate is only 33%.Through the analysis of the biofilm community structure,the stable existence of Diaphorobacter sp.in microorganisms indicates that it plays an important role in the degradation of toluene.In this paper,the degradation characteristics of the degrading bacteria and single bacteria were studied,and the single bacteria in the biological trickling filter was used to enhance the activated sludge to purify the benzene series waste gas,and the basic parameters were obtained,which have guiding significance for practical applications.