Experimental Studies on Decolourization of Azo Dye in Textile Effluent by using Bio Remediation Technique

Studies were carried out on the decolorization of azo dyes by Bacillus species from effluent of textile industries. About 10 bacterial strains were isolated from the effluent of textile industries, Bacillus sp. showed remarkable ability in decolorizing the widely utilized azo dyes. Phenotypic characterization and phylogenetic analysis based on 16S rDNA sequence comparisons indicate that these strains belonged to the genus Bacillus subtilis. It showed nearly 90% decolorization ability within 3 days of incubation. Textile wastewater having diverse characteristics could be decolorized effectively using Bacillus subtilis. The Bacillus subtilis could decolorize azo dyes in a wide range of salt concentration (up to 20% w/v), temperature (25– 40 o C), and pH (5–11) after 4 days of incubation in static culture. Bacillus subtilis readily grew in and decolorized the high concentrations of dye (5000 ppm). UV–Vis analyses before and after decolorization and the colorless bacterial biomass after decolorization suggested that decolorization was due to biodegradation, rather than surface adsorption.