Investigation of Decolorization of Reactive Violet 5R and Remazol Brillant Orange 3R by

Abstract

Dye pollution in water and soil is increasing rapidly depending on the industrialization. Synthetic dyes are mutagenic, toxic and resistant to degradation due to their complex chemical structures so their effluents cannot be directly discharged. The biological remediation of textile effluents has recently received an increasing attention, representing an attractive, cheap, environmentally friendly, and publicly acceptable alternative to the physico-chemical methods. Microorganisms play an important role in the decolorization and removal of dyes from polluted sites. In this study, decolorization of RV-5R and RBO-3R by Bacillus sp. which was isolated from textile effluent was investigated. The effect of environmental factors such as pH (5.5, 6.5, 7.5, 8.0, 9.0 and 10.0) temperature (20, 30, 37 and 42 °C), carbon (1 g/L: sucrose, glucose, starch and mannitol) and nitrogene sources (ammonium chloride, peptone and yeast extract) and initial dye concentration (10, 25, 50, 100, 200, 500 mg/L) on the microbial decolorization by Bacillus sp. was investigated. The maximum dye removal was obtained at 500 mg/L initial dye concentration for RV-5R and 200 and 500 mg/L for RBO-3R by the bacterium. Bacterial decolorization of RV-5R was 54.54% (6h) in growth medium containing yeast extract (1g/L) and glucose (1g/L) at pH 10.0 and 37 °C.The same bacterium decolorized the RBO-3R dye at 96.15% (172 h) in growth medium containing peptone (1g/L) and sucrose (1g/L) at pH 10.0 and 30 °C. Any report about the microbial decolorization of the RV-5R and RBO-3R dyes has not been seen in the literature. Therefore this study was the first report about the bacterial decolorization of these dyes

Keywords

• Bacillus, decolorization, optimization, RV-5R, RB0-3R