Package Pringting And Painting Exhaust Gas Treated By Biotrickling Filter

In this research,a biotrickling filter tower is used to treat packaging printing and painting exhaust gas.Toluene and ethyl acetate were used to simulate printing exhaust gas,nitryl thinner and acrylic thinner were used to simulate painting exhaust gas.Screened the dominant strains that can degrade the mixture of toluene and ethyl acetate,acrylic thinner,and nitryl thinner,respectively,on the plate medium.Used fatty acid identification and16SrDNA identification identified the dominant strain.The dominant strain was filmed on the biotrickling filter to treat the corresponding simulated exhaust gas,study the impact of inlet concentration,EBCT,spray volume on the treatment efficiency to optimize the performance and study the dynamic.The bacterias within the tower were identified after the stable operation and compared the result with the dominant strain screened on the plate medium.Contaminant components and intermediate components during the degradation of the biotrickling filter were determinated by GC in order to analyze the mechanism of degradation of pollutants by microbial.The results showed that the dominant bacterias screened on the plate medium that degraded the mixture of toluene and ethyl acetate were Elizabethkingia-meningoseptica,Bacillus-cereus-GC subgroup A,Stenotrophomonas-maltophilia;The dominant bacterias degraded nitro thinner was Lysinibacillus-sphaericus,Bacillus-cereus-GC subgroup A,Ochrobactrum-anthropi;The dominant bacterias degraded acrylic thinner were Empedobacter-brevis,Stenotrophomonas-maltophilia,Bacillus-megaterium-GC,Variovora x-paradoxus-GC,Xanthobacter-agilis.However,there are differences in the results of fatty acid identification and 16SrDNA identification methods,which may be due to the variation of bacterial species during storage.The optimum processing conditions for packaging printing waste gas were:inlet concentration was 800 mg/m~3,spray volume about 800 L/h,residence time was 75 s,the removal rate was 80%;The optimum processing conditions for nitryl thinner were:inlet concentration was 30 mg/m~3,spray volume about 800 L/h,residence time was 75 s,the removal rate was 70%;The optimum processing conditions for acrylic thinner were:inlet concentration was 500 mg/m~3,spray volume about 800 L/h,residence time was 75 s,the removal rate was 75%;Ignoring the existence of liquid membranes,the kinetic model of toluene in the biotrickling filter tower was simulated using the“adsorption-biomembrane”model.It was found that when the inlet concentration was less than 500 mg/m~3,the model was met,and the curve fitting correlation coefficient was more than 0.99,but when the inlet concentration was more than 500 mg/m~3,it did not meet the model very well.Taking into account that the amount of spray would affect the treatment process,so we can not ignore the existence of liquid film,then verified that when the inlet concentration was more than500 mg/m~3,using the“absorption-biomembrane”model was more suitable;Identification of the bacteria in the tower using two methods had consistent results,the dominant bacterias in the tower that degraded the mixture of toluene and ethyl acetate were Stenotrophomonas maltophilia,Bacillus cereus,Bacillus subtilis,Pseudomonas;The dominant bacterias degraded nitro thinner were Bacillus cereus,Bacillus subtilis,Bacillus sp.GC group 22;The dominant bacterias degraded acrylic thinner were Bacillus cereus,Bacillus subtilis,Acinetobacter acetate,Bacillus bellis.However,this is not the same as the identification result of the dominant bacteria selected in the laboratory’s culture medium in the previous period.It is suspected that at different times and under different growth conditions,certain strains are at a disadvantage in the survival competition and are eliminated,or variants have been mutated;The main components of the three simulated exhaust gases are toluene,ethylbenzene,and xylene,and detected several of the same degradation intermediates,that was ketones,alcohols,and peroxides.The analysis of the degradation of toluene,ethylbenzene,and xylene by microorganisms is:first,phthalocyanine is produced by the action of toluene monooxygenase or toluene dioxygenase,and then the ring opened at different sites by the action of catechol dioxygenase,then produced alcohol,ketonebeing by oxidation or reduction,or further oxidated to peroxide.