Optimization of process conditions for decolorization of azo dye by an efficient broad-spectrum dye decoloring bacteria strain

Decolorization of textile azo dye Acid Red 3R was carried out from simulated aqueous solution by a broad-spectrum decoloring strain Enterobacter cloacae strain M3.Based on the single factor experiment, response surface methodology involving Box-Behnken design matrix in three most important operating variables: temperature, initial dye concentration and yeast powder concentration was successfully employed to study interaction effects of independent factors and optimization of decolorization process. A predictive polynomial quadratic equation model was developed and the optimum conditions for decoloring Acid Red 3R wastewater were determined. The results showed that regression equation was significant and can be used to navigate the design space. Model indicated that 36°C, initial dye concentration of 121.12 mg/L and yeast powder concentration of 1.99% were found optimum for maximum decolorization rate. Under this conditions, the decolorazation rate of Acid Red 3R was 99.21%. The experimental results were in good agreement with the predicted values of the model equation with only 0.79% deviation.