Abstract:[Objectives] To screen effective bacterial strains capable of decolorizing azo dyes containing wastewater from dewatered sludge. [Methods] nine bacterial strains (named T-1?T-9) capable of decolorizing mixed azo dyes were isolated from the dewatered sludge in municipal wastewater treatment system after proper acclimation. physiological and biochemical tests and 16S rRNA gene based bio-molecular identification were adopted to identify the isolates. Decolorization performances of pure cultures and mixed cultures of the isolates were determined and compared. Isolated strain T-8 was used to prepare dry powder and consequent determination of decolorization performance. [Results] Nine isolates belong to Bacillus sp., Exiguobacterium sp., Stenotrophomonas sp. and Paracoccus sp. according to preliminarily identification. The structure and concentration of azo dyes had a certain impact on the decolorization efficiency during domestication. T-8 had the best decolorization rate 85.9% for methyl orange and 86.2% for golden orange I in 40 h. The dry powder of T-8 was equally active to its origin isolate, which is confirmed by complete decolorization of golden orange I in 4 days without external carbon resource. Mixed culture of all isolates was obviously better in the decolorization (90.1%) of mixed zao dyes than pure culture did. [Conclusion] This study suggests that, as a new source for the functional flora of decolorizing azo dyes, the dewatered sludge and its isolates are of great value in zao dye containing wastewater.
