LAUSR

Abstract The present study refers to application of Saccharomyces cerevisiae for bioremoval of very low amounts of heavy metals from aqueous media. The impact of process variables on biosorption of lead (II) and cadmium (II) by S. cerevisiae was first evaluated with Taguchi screening design. After determining of significant variables, optimization of biosorption process was performed by 3 independent parameters (pH, biomass, initial ion concentration) using a central composite design. So, twenty test runs were done and the experimental data fitted to the second-order polynomial models. The analysis of variance of the quadratic models showed that the models are highly significant. The adjusted conditions in the best set was 5, 52.5 µg/l and 32.5 × 107 CFU for pH, heavy metal concentration and biomass, respectively. Behavior of biosorption system in a batch process was analyzed by 3D plots which represented dual simultaneous interaction effects of variables on metal biosorption yield. The model explained that heavy metal biosorption in aqueous solution is affected by all the three factors studied. An optimum lead (II) and cadmium (II) biosorption yield of 70.3% and 76.2% were found at initial ion concentration of 65.0 and 62.6 µg/l, and S. cerevisiae of 15.0 and 15.2 × 107 CFU, respectively. The results suggest that S. cerevisiae, as a natural, low-cost and abundant sorbent, has the potential to be used in biosorption of very low concentrations of lead and cadmium, which is useful to reduce the contaminations of drinking water and foodstuff with green technologies.