Simultaneous bioaccumulation of reactive dye and chromium(VI) by using thermophil Phormidium sp.

Abstract

Co-existence of a reactive dye and chromium(VI) in industrial wastewater effluents is an environmental problem associated with their resistance to various microbial treatment procedures. Previously we demonstrated that the thermophilic cyanobacterial strain Phormidium sp. was suitable for effective biological treatment of such wastewater samples. Thus, we found it relevant to investigate simultaneous bioaccumulation capacity of chromium(VI) and reactive dye, Black B or Remazol Blue by the strain in a batch system. The experimental results showed that the strain tolerated high initial dye and chromium(IV) concentrations varying from 11.8 up to 84.5 mg l −1 Remazol Blue or Reactive Black B and 5.8–19.9 mg l −1 chromium(VI), respectively, at pH 8.5 and 45 °C. The bioaccumulation yields were measured and compared at these conditions, the results showed that the yields were higher at lower initial dye and chromium(VI) levels. The maximum dye yield was found at 5 mg l −1 initial chromium(VI) level and the amount of yield varied within 10.4–69.9% range at all of the dye concentrations. The maximum chromium(VI) bioaccumulation yields were found at 12.5 mg l −1 initial dye concentration, ranging from 1.8 to 28.8% for all tested chromium(VI) concentrations. The effect of different temperatures on reactive dye and chromium(VI) bioaccumulation levels were also investigated at about 25 mg l −1 initial dye and different chromium(VI) concentrations of 5–10 mg l −1 range. The highest uptake yields obtained at the samples with the lowest chromium(VI) level at 40 °C temperature: 35.9% for the dye and 28.5% for chromium(VI) in samples with Reactive Black B and 31.8% for the dye and 19.4% for chromium(VI) in the samples with Remazol Blue.