Optimization of Chromium Removal by the Indigenous Bacterium Bacillus spp. REP02 Using the Response Surface Methodology

Abstract

An indigenous bacterium, Bacillus REP02, was isolated from locally sourced chromium electroplating industrial effluents. Response surface methodology was employed to optimize the five critical medium parameters responsible for higher % Cr 2+ removal by the bacterium Bacillus REP02. A three-level Box-Behnken factorial design was used to optimize K 2 HPO 4 , yeast extract, MgSO4, NH 4 NO 3 , and dextrose for Cr 2+ removal. A coefficient of determination ( R 2 ) value (0.93), model F -value (3.92) and its low P -value ( F < 0.0008 ) along with lower value of coefficient of variation (5.39) indicated the fitness of response surface quadratic model during the present study. At optimum parameters of K 2 HPO 4 (0.6 g L −1 ), yeast extract (5.5 g L −1 ), MgSO 4 (0.04 g L −1 ), NH 4 NO 3 (0.20 g L −1 ), and dextrose (12.50 g L −1 ), the model predicted 98.86% Cr 2+ removal, and experimentally, 99.08% Cr 2+ removal was found.