Inhibitory effects of chromium(VI) and Remazol Black B on chromium(VI) and dyestuff removals by Trametes versicolor

Many dye-bearing wastewaters also contain heavy metal ions. Although the decolorization of single reactive dye or the uptake of single heavy metal ions by various growing cells has been extensively studied, very little attention has been given to the simultaneous bioremoval of reactive dye-metal ion systems. In this study, the single and combined effects of chromium(VI) and Remazol Black B reactive dye on the chromium(VI) and dye removal properties of adapted Trametes versicolor, a white-rot fungus, was investigated in a batch system at different levels of chromium(VI) and dye. Removal studies were performed at an initial pH of 4.0. Chromium(VI) uptake studies were carried out in two different growth media; mainly containing glucose and reduced quantity of glucose and whey. As the maximum microbial chromium(VI) uptake was accomplished in glucose + whey medium, single dye and binary dye-chromium(VI) bioremoval studies were also performed in this culture medium. Although the single removal of chromium(VI) and dye was enhanced with increasing initial concentration of each component up to 30 mg l−1 for chromium(VI) and up to 400 mg l−1 for dye, in general the presence of increasing concentrations of chromium(VI) ions much more severely inhibited the dye bioremoval by T. versicolor. While single chromium(VI) uptake efficiency was 32.2% in 30 mg l−1 chromium(VI) containing growth medium and single dye removal percent was 77.0% in 400 mg l−1 dye-bearing growth medium, the fungus was only capable of 10.8 and 13.3% removals of chromium(VI) and Remazol Black B dye, respectively, in the growth medium containing the binary mixture of these components at the above concentrations.