Optimization of biological treatment of a dye solution by macroalgae Cladophora sp. using response surface methodology

In this paper biological treatment of Malachite Green (MG) solution using macroalgae Cladophora sp. has been reported. Response surface methodology (RSM) was employed to investigate the effect of key factors on the biological treatment. The variables investigated were the initial pH, initial dye concentration, algae amount and reaction time. Central composite design (CCD) was used for the optimization of biological decolorization process. Predicted values were found to be in good agreement with experimental values (R2 = 0.9740 and Adj-R2 = 0.9512), which indicated suitability of the model employed and the success of CCD in optimizing the conditions of biological decolorization process. The results of optimization predicted by the model showed that maximum decolorization efficiency was achieved at the optimum condition of the initial pH 8, initial dye concentration 10 mg/l, algae amount 4 g and reaction time 75 min. Biological degradation of MG was revealed on the basis of live and dead biomass comparison, repeated-batch operations and UV–Vis, FT-IR spectra of MG solution during biological decolorization treatment.