Biodecolorization of disperse blue 183 from textile effluents

Abstract

Removal of synthetic dyes is one of the main challenges before releasing the wastes discharged by textile industries. In the last few years, intensive research has been carried on decolorization of dyes and textile wastewaters by various technics including physical and chemical. As a viable alternative, biological processes have received increasing interest owing to their cost, effectiveness, ability to produce less sludge and environmental benignity. This study was conducted to show the efficiency of bacteria on decolorization of disperse dyes. The samples were collected from Kashan textile wastewater in screw capped sterilized bottles aseptically and transported to the laboratory. Bacterial isolates were obtained by a surface-spread plating method on nutrient agar containing NaCl concentration. The bacterial strains were identified by color, size, morphology of the colonies and biochemical tests. A bacterial strain was selected; with ability to decolorize Disperse Blue 183 (DB-183). This gram positive bacteria showed great capability to decolorize in pH 8-10 and 32 °C. This bacterial strain grew well in medium containing 50 ppm of DB-183, resulting in approximately 90% decolorization at 72h, and could tolerate up to 200 ppm of DB-183. UV-Vis spectrophotometer analyses before and after decolorization and the colorless bacterial biomass after decolorization suggested that decolorization was due to biodegradation, rather than inactive surface adsorption. To conclude the present study reveals that this gram positive bacteria is promising for its application in decolorization of disperse dyes in textile effluents.