Packed bed column studies for the removal of synthetic dyes from textile wastewater using immobilised dead C. tropicalis Original Research Article

An efficient dye biosorbent was developed for the treatment of textile wastewater by entrapping dead cells of C. tropicalis, within sodium alginate matrix. The biosorbent performance was evaluated in packed bed column with different pH (3 to 6), wastewater strength (25%, 50% 75%), bed height (5 cm–15 cm) and flow rate (0.5 mL min−1 to 1 mL min−1). pH 5, undiluted wastewater, bed height 15 cm and flow rate 0.5 mL min-1 were found to be optimum for dye biosorption. The linearized form of the modified Thomas model equation fitted well with the experimental data and described the dynamic adsorption of synthetic dyes from textile wastewater. The Bed depth service time model was used to express the effect of bed height on breakthrough curves. Dye laden immobilised dead C. tropicalis was regenerated using 0.01 mol L−1 NaOH at an elutant flow rate of 1 mL min−1. The reusability of the immobilised biomass was tested in consecutive adsorption–desorption cycles. The FT-IR spectral analysis showed the involvement of amine, hydroxyl, carbonyl, amide and phosphoryl groups in biosorption of dyes from wastewater. The analysis of treated samples showed almost zero colour and a significant decrease in Total Dissolved Solids (TDS).