Single and binary dye and heavy metal bioaccumulation properties of Candida tropicalis: Use of response surface methodology (RSM) for the estimation of removal yields

The single and binary effects of initial Remazol Turquoise Blue-G (RTBG) reactive dye and initial copper(II) concentrations on the dye or/and copper(II) bioaccumulation efficiency of C tropicalis was investigated in 10 g l(-1) molasses sucrose containing growth medium at an initial pH value of 4.0 and optimized using response surface methodology (RSM). A 2(2) full factorial central composite design was successfully used for experimental design and analyses of the results. Two numerical correlations fitted to a second-order quadratic equation were obtained to estimate the responses of dye and copper(II) removal yields. The statistical analysis indicated that although relatively high accumulation efficiency of C tropicalis was obtained for the single removal of dye and copper(II), individual uptake of both the components from binary mixture was affected negatively by the addition of other component up to 500 mg l(-1) due to inhibition caused by high concentrations of RTBG dye and copper(II). The optimum combination predicted via RSM confirmed that growing C tropicalis was capable of bioaccumulating RTBG and copper(II) with the maximum yields of 59.2% and 21.3% in the growth medium containing 50 mg l(-1) RTBG and 50 mg l(-1) copper(II) together, respectively. (C) 2009 Elsevier B.V. All rights reserved.