COMPARISON OF THE HEAVY-METAL REMOVAL EFFICIENCY OF BIOSORBENTS AND GRANULAR ACTIVATED CARBONS

The adsorption efficiencies of granular activated carbon (GAG) and bio sorbents: Saccaromyces cerevisiae yeast (caustic treated and active) i mmobilized in GAG; Yeast( caustic treated) immobilized in alginate aci d, and alginate itself were compared for the removal of Cu2+, Cd2+, Zn 2+ from simulated waste waters. Yeast biomass has a high capacity for uptake of heavy metal ions, and can be adsorbed on activated carbon. T he alginate used in this study was used as an entrapment material to i mmobilize yeast. It was observed that the pH of the solution was a cri tical parameter for the adsorption process; the value chosen in the ex periments was 4.5. Two different experimental modes were used, a batch mode and a flow mode were used. In batch mode operation, using biosor bents yeast immobilized on GAC and on alginate, the percentage removal of heavy metal can exceed 90%. When only GAC was used as an adsorbent , acceptable results were obtained. Comparing the two different experi mental modes, no difference was observed in the percentage removal of metal ions, although a longer time was needed for the now system to re ach adsorption equilibrium compared to batch mode.