Bioremoval of the indigo blue dye by immobilized microalga <i>Chlorella vulgaris</i> (PSBDU06)

Abstract

In the present study, microalga <i>Chlorella vulgaris </i> (PSBDU06) was immobilized with sodium alginate to clinch its conceivable for decolorizing indigo blue dye under various set of factors. The microalgal immobilized beads were evaluated at different pH (5, 6, 7, 8 and 9), incubation time (6, 12, 18 and 24hours), algal cell concentration in beads (25000, 50000, 100000, 200000, 400000 and 800000cells/ml) and beads density (25, 50, 75, 100, 125 and 150 numbers). Reusability of algal biomass was also examined by the HNO₃ desorption studies. The acid and base properties of wastewaters, incubation time, algal cell concentration and variation in beads density were significantly influenced the rate of dye decolorization. The lowest pH (5) and longest incubation time (24 hours) showed maximum decolorization (33%). At 50,000 cells/ml of algal cells concentration with 100 numbers of beads densities had result the highest dye decolorization (49.03%). The rate of elimination of the dye in the effluent was about 27% after the third cycle. Infra-red analyses of the algal beads were done scanning from 500 to 4,000 cm⁻¹. This revealed the presence of functional groups associated with the algal beads and dye that provided possible explanations for the decolorization of the dye under various factors.