Isolation And Characterization Of Bacteria For Decoloring Of Azo Dye Acid

At present the treatment of dye wastewater with physical and chemical method andbiological process, compared with biological treatment method has low energy consumption,low cost, high efficiency, less pollution two, which can be widely accepted environmentalprotection treatment method become a focus of research at home and abroad. However, to date,studies on microbial degradation of dye the focus on the fungus, study of bacteria. This study isdevoted to the little microbial for efficient, broad-spectrum degradation ability to dye, strainidentification on it, on the dye degradation characteristics, so as to establish microbialscreening method, and used to solve the practical problems. Has applied to dye wastewatertreatment theory significance and practical application value, satisfy the need of sustainabledevelopment of printing and dyeing industry.Five strains were isolated from the drain age of wastewater treatment plant which was froma textile factory. Each of three strains of bacteria（B1、C3、E2）, one mold strains （G7）was thebest. These strains were identified as [Bacillus cereus]（B1）、[Geotrichum candidum]（C3）、[Enterococcus faecalis]（E2）、[Candida tropicalis]（G7）.The biodegradation characterizationin vitro was studied.The culture conditions were optimized. The medium compositions were optimized withorthogonal experimental design. The result showed the optimal culture conditions includedinoculum temperature28℃, pH7, Micro aerobic. And the optimal medium contained：Glucose8g/L, Beef extract2ï¼›Peptone1ï¼›FeSO₄.7H₂O0.04ï¼›MgSO₄.7H₂O0.5ï¼›Na2HPO₄4.26ï¼›KH₂PO₄2.65ï¼›MnSO₄·7H₂00.02ï¼›CaCl₂0.02ï¼›NH₄Cl0.5ï¼›Trace element solution1ml。The decolorizing effect of the dyes by the single strain and mixed bacteria groups had beencompared. Finally, the mixed bacteria group （B1+C3+E2） which could remove the Direct Blue92.38%in2days had been determined to be the best group. Single strain and the best mixedbacteria group were studied on the conditions and the mechanism of decoloration. The resultsindicated that the decolorizing ability of the mixed bacteria group superior to the single strain.The mixed bacteria group could endure the dye to the concentration of2g/L.It’s optimumrange of pH value was4⁷, and the decoloration rate of different dyes can reach over80%within2days. The Direct Blue was degraded to form a new product with maximum absorptionwavelength at260nm.