Biosorption of Cr (VI) from aqueous solutions by biomass of Agaricus bisporus.

In this study, biosorption of Cr (VI) ion was investigated by using biomass of Agaricus bisporus (a species of mushroom) in a temperature and shaking speed controlled shaker. The effect of shaking speed, biomass concentration, initial metal ion concentration and initial pH on biosorption yield was determined and the fitness of biosorption data for Freundlich and Langmuir adsorption models was investigated. Optimum biosorption conditions were found to be pH 1, C0=50 mg/l, m=10 g/l, shaking speed=150 rpm, T=20 degrees C Cr (VI), respectively. It was found that biosorption of Cr (VI) ions onto biomass of A. bisporus was better suitable to Freundlich adsorption model than Langmuir adsorption model. The correlation coefficients for the second-order kinetic model obtained were found to be 0.999 for all concentrations. These indicate that the biosorption system studied belongs to the second-order kinetic model.

Removal of divalent heavy metal mixtures from water by Saccharomyces cerevisiae using crossflow microfiltration.

The removal of heavy metal ions, Ni2+, Cu2+ and Pb2+ using yeast (Saccharomyces cerevisiae) as carriers in a crossflow microfiltration is investigated. The effects of yeast cell and electrolyte concentrations on the transient and steady-state permeate flux and metal ion rejections are established. It is found that the metal ion rejection reaches a plateau if yeast cell concentration is greater than approximately 2 g/l as a result of cell aggregation. The binding affinity of the metals to yeast cell is Pb2+ > Cu2+ > Ni2+, which is also reflected in the metal ion rejection under identical process conditions. Because of the formation of yeast cell flocks in the presence of Pb2+, permeate flux is also higher for this metal. The presence of NaCl decreases both rejection and permeate flux for Ni2+ and Cu2+ but not for Pb2+. When binary or ternary metal mixtures are used, the rejection of the individual metals is reduced except that of Pb2+. It is found that the pseudo-gel concentration is unaffected by the presence of metal ions.