Isolation, Identification And Immobilization Of Bis(2-ethylhexyl) Phthalate-degrading Bacterial Strains

Three bacterias,which could utilize di(2-ethylhexyl)phthalate(DEHP)as sole carbon source,were isolated from activated sludge in sewage treatment factory and landfill leachate in refuse landfill and was named as S1,S2,S3,respectively.The three bacterias were identified through physiological biochemistry test and 16 S rDNA sequencing.Growth and degradation characteristics of the three bacterias were investigated and the technological conditions were optimized.The degrading broad spectrum was studied.The bamboo charcoal/polyurethane composite material was prepared and the influence of bamboo charcoal additive amount on composite materials was studied.The degradation characteristics of immobilized and free microorganism were discussed.The results showed that the strain S1 was identified preliminarily as Delftia sp.,the strain S2 was identified preliminarily as Comamonas testosterone..the strain S3 was identified preliminarily as Chryseobacterium sp..The optimal growth condition of strain S1 were pH7-8,30?,DEHP concentration of 800mg/L.The optimal growth condition of strain S2 were pH7-9,30?,DEHP concentration of 400-800mg/L.The optimal growth condition of strain S3 were pH8,30?,DEHP concentration of 800mg/L.The results of degradation technological optimization exhibited that the proper conditions for degradation of S1 were pH8,30?,adding amount of bacteria(5%),DEHP concentration of 800mg/L;S2 were pH8,30?,adding amount of bacteria(5%),DEHP concentration of 400mg/L;S3 were pH7,30?,adding amount of bacteria(10%),DEHP concentration of 400mg/L.DEHP concentration of 800mg/L could be completely degraded within 72 h by S1.S2 needed 72 h to degrade 400mg/L DEHP completely and S3 needed 120 h.Degrading broad spectrum of stains presented that three stains could degrade DMP,DEP,DBP and DNOP.Degrading efficiency of S1 could be up to 60% and S2 could be up to 50%.The degrading efficiency of S3 for DMP and DEP could be up to 70%,but for DBP and DNOP could be about 40%.The synthesis of poly(propylene glycol)phosphate as a modifier was uesd to modify the surface of nano bamboo charcoal.The experiments showed that poly(propylene glycol)phosphate could improve the dispersion of nano particles and its optimal dosage of 3%.Modified nano bamboo charcoal and polyurethane were composited.It found that the addition of nano bamboo charcoal had not changed polyurethane internal structure and improved the chemical stability of composite carrier to some extent,enriched the porosity of the composite carrier.Through the experiment to determine immobilization condition were that bamboo charcoal/polyurethane composite as the carrier were immobilized and the carrier bamboo charcoal content of 3%,the carrier in an amount of 0.025 g,contact time was 24 h.The maximum absorption amount of strain S1,S2,S3 were 0.216mg/g,0.204mg/g,0.212mg/g.The degradation characteristics of immobilization microorganism and free bacteria were studied.The results presented that the stagnation of immobilized strains were shortened and the degradation rate and effective of DEHP significantly improved after S1,S2,S3 and microbial flora were immobilized in bamboo charcoal/polyurethane composite.