Modeling of chromium (VI) biosorption by immobilized Spirulina platensis in packed column.

This study describes biosorption of chromium (VI) by immobilized Spirulina platensis, in calcium alginate beads. Three aspects viz. optimization of bead parameters, equilibrium conditions and packed column operation were studied and subsequently modeled. Under optimized bead diameter (2.6mm), calcium alginate concentration (2%, w/v) and biomass loading (2.6%, w/v) maximum biosorption was achieved. 140 g l(-1) loading of optimized beads resulted in 99% adsorption of chromium (VI) ions from an aqueous solution containing 100 mg l(-1) of chromium (VI). The quantitative chromium (VI) uptake was effectively described by Freundlich adsorption isotherm. The immobilized S. platensis beads were further used in a packed bed column wherein the effects of bed height, feed flow rate, inlet chromium (VI) ion concentration were studied by assessing breakthrough time. The performance data were tested for various models fitting in order to predict scale up-design parameters such as breakthrough time and column height. Results were encouraging.