Process Characteristics And Mechanism Of Styrene Biopurification With Biological Trickling Filter

Styrene is a class of hydrophobic,bioaccumulative toxic VOCs,also be an important chemical materials and synthetic rubber monomer.With widespread and increasing demand use of styrene,the volatile substances and carcinogenic damage to the ecological environment and human health risk is also increasing.Research on microbial purification of styrene gas is still hot in the field of environmental science and technology,and efficiency strains obtained is the key for its industrial application.In this paper obtained by screening a bacteria strain was identified as Pseudomonas putida,named WJ,Focus on basic degradation characteristics and kinetic behavior of strain WJ,and environmental factors,the strain degradation ability of different carbon sources,and speculated the strain probable biological degradation pathway of styrene.The strain has applied to obtain the gene sequence GenBank accession number JX569146,Currently,deposited at Wuhan University China Center for Type Culture Collection(CCTCC),Accession No.M 2012295.Based on the results of the biochemical characteristics of the strain WJ.Sucessfully applied to the strain WJ on polyurethane filler biological trickling filter and zeolite filler biological trickling filter to reinforce biological purification of styrene exhaust.Study on pollutant removal performance,pressure drop and biofilm completion during the system start-up period to compare the differences,emphasis study on the operational phase inlet concentration and EBRT parameters changes during the system stability period,by SEM analysis of biofilm,biofilm activity test,PCR-DGGE to analysis inside of BTF microbial activity,distribution and evolution.Obtain the following results:(1)Obtain a efficiency degrading of styrene strain Pseudomonas putida,determine the optimal culture conditions temperature of 30 ℃,pH value of 7 by single-factor test,under the conditions of the strain growth and efficiency degradation of styrene significant role in promoting oxidative degradation.Strain WJ can completely degradation initial concentrations of styrene below 1500 mg·L-1,but when the initial concentration of styrene reached 2000mg·L-1,the growth and metabolism of the strain was significantly inhibited.(2)The different cations effects on the strain degrade performance are significant differences,NH4+ has a significantly role in promoting strain grown and degradation,Mg2+,Ca2+ has a significantly inhibited on the grown and degradation of strain,while K+,Fe3+,Na+ has little effect on the growth of degradation of strain.(3)The growth kinetics behavior of the strain WJ degradation are consistent with Haldane’s model,the obtained experimental data with the model predictions are a high correlation coefficient,the corresponding degradation kinetics parameters:vmax= 0.282 h-1,KS= 23.57 mg·L-1,Ki=1784.56 mg·L-1,R2= 0.955;the growth kinetics parameters:μmax=0.0736 h-1,KS= 18.57 mg·L-1,Ki= 1845.13 mg·L-1,R2= 0.916.(4)Strain WJ degradation ability on different carbon sources tests showed that similar to the structure of hydrocarbons with styrene such as BTEX,n-hexene has a good removal efficient by strain,but for chlorobenzene,methylene chloride,halogenated hydrocarbon is basically can not be use by strain.The main possible ways by strain WJ oxidative degradation of styrene are oxide vinyl side chain.(5)Based on the degradation efficiency of styrene strain,applied to reinforce the BTF purification of styrene exhaust,which were established with PU-BTF and Z-BTF to purified styrene exhaust.In the start-up period,PU-BTF and Z-BTF biofilm completed in the 24d and 22d,styrene removal efficiency about 53%,50%,respectively.(6)The stable period of PU-BTF and Z-BTF have better removal efficiency on styrene,under the same conditions PU-BTF removal efficiency slightly higher than Z-BTF.Wherein PU-BTF system in the ambient condition change exhibited stabilization of the system better than the Z-BTF system,indicating that the system can adapt to changes in fluctuations,fluctuations in the gas concentration process conditions.(7)DGGE profiling in PU-BTF system lane striping similarity differences are significant,clear and bright bands,indicating that changes in microbial community structure trickling tower obviously,the main microbial communities with high stability;in Z-BTF system lane striping closer similarity values,and less number of stripes and bands dim,indicating that the microbial communities within the Z-BTF more single,simple.The main advantage of both system are basically the same,tapping recycling sequencing results validate the initial start adding efficiently strain of Pseudomonas putida to BTF gradually become dominant bacteria,play the role to reinforce BTF.(8)Microbial activity analysis shows PU-BTF system uses nutrient solution elements more than Z-BTF,and utilization of the different elements of the two obvious differences,the former biofilm activity indirectly reflects better pollutant removal more,coincide with PU-BTF system than styrene removal system Z-BTF higher results.Biolog ECO AWCD microplate analysis also showed the value of a polyurethane filler AWCD values higher than zeolites indicate that the biological activity of PU-BTF in greater than Z-BTF,which may be the PU-BTF representing the type and quantity of microorganisms more than Z-BTF.