RESPONSE SURFACE METHODOLOGY FOR BIOTRANSFORMATION OF Cr ( VI ) USING Salmonella sp . S 4

The present study was an attempt to explore the efficiency of indigenous bacterium isolated from the effluent of Electroplating Industry in transforming hexavalent chromium into trivalent chromium. The isolated bacterium was characterized on the basis of its morphological, biochemical and physiological properties as Salmonella sp.S4. Response Surface Methodology (RSM) based on a three-level three-variable Box-Behnken experimental design was employed to study the interactive effect of three vital parameters viz pH (4-8), temperature (25 – 35 C) and initial Cr(VI) ion concentration (10-40 mgl) on biotransformation of Cr(VI) ions. Experimental result concluded that using optimum conditions of pH 6.0, temperature 30C and initial Cr(VI) ion concentration 25 mg/L, maximum Cr(VI) transformation of 74% could be achieved which was in close agreement with the model values. Statistical analysis involving analysis of variance (ANOVA) and Student’s t-test were performed which gave coefficient of determination (R) value 0.9584, model Fvalue 17.90 and low P-value (F < 0.0005) ensured fitness of second order polynomial equation with experimental data.