Study On Isolation,Identification And Characteristics Of Bacteria For Decolorizing Azo Dye

DDue to the stable molecular structure,azo dyes are difficult to be degraded in nature.The deleteriousness of azo dyes will also cause potential safety hazard if being discharged into the natural environment without treatment.The biological treatment method of azo dye wastewater has the advantages of low cost,and non-secondary pollution.However,the great deleteriousness and poor biodegradability of azo dye wastewater make it fail to achieve better treatment effect through general sewage treatment bacterial strain.The factors,such as fewer azo dyes decolorizing bacteria species,lower decolorization rate,andstrict application conditions restrict the development of biological treatment method of azo dye wastewater.Therefore,the paper focuses on developing efficient decolorizationbacteria of azo dyes,and systematically researches its characteristics and the influencingfactors of decolorization effect.The study has important theoretical significance and practical value for enriching azo dyes decolorizing bacteria species and improving the biological treatment ability of azo dye wastewater.8 pieces of bacteria were isolated from the wastewater activated sludge of the municipal sewage treatment plant and the river beside the printing and dyeing mill,dye concentration gradient pressurization was used to acclimatize and isolate decolorization bacterial strain for azo dyes.Chose EWA2 strain the decolorizing ability is the best of 8 pieces of bacteria for the further study.Physiological and biochemical reaction and 16 S r DNA sequence indicated that EWA2 belonged to Proteus mirabilis.Based on the identification of the bacterial strain,the growth and decolorization characteristics the bacterial strain were studied and its decolorizing pathway was preliminarly explored.The decolorization ability and the influencing factors of EWA2 were studied through Reactive Black 5 and the simulated dye wastewater.In LB medium,the decolorization rate of Reactive Black 5(50 mg/L)reached 100% in 24h;that of Reactive Black 5(300 mg/Land 400mg/L)reached 94.7% and 83.8% in 48h;that of Reactive Black 5(400 mg/L)reached 100% in 96 h.In simulative dyeing wastewater,when EWA2 strain could use sodium carboxy methyl cellulose and glucose as the carbon source.The decolorization rate of Reactive Black 5(50 mg/L)reached 91.9%under the best condition income study.Under the optimal conditions obtained from experiments,the decolorization rate of Reactive Black 5(below 200 mg/L)reached99% in 96 h,which presented the decolorizing performance for Reactive Black MES in practical production application as good as that for Reactive Black 5.Through the comparing decolorizing inactivated bacteria and viable bacteria,as well as the spectrum scanning and water quality index,the decolorizing pathwayof EWA2 strain was preliminarily studied.The results showed that the decolorizing pathway of EWA2 for Reactive Black 5 was mainly degradation.The inherent extracellular enzyme of EWA2 strain play an important role in reductase of azo dye.