A SPIRAL BIOREACTOR FOR REMOVAL AND RECOVERY OF METALS FROM AQUEOUS WASTES

Microorganisms from activated sludge were immobilized on a spiral reactor fabricated from a PVC-Silica based biosupport, and used to biosorb lead from synthetic waste streams. Biosorption parameters determined for lead from Freundlich isotherms indicate that 89% of the binding capacity of that observed in suspended cell system is retained in the spiral bioreactor. More than 87% of biosorbed lead was recovered each time after breakthrough by dilute acid washing between the pH of 2 to 2.5. No significant changes in the biosorption pattern was observed over several adsorption and recovery cycles that were conducted. The spiral bioreactor is better than suspended cell systems because it provides comparable surface area as that in the suspended cell system in an immobilized (small volume) form. It is also better than the entrapped microbial cell reactors because it eliminates mass transfer resistance across the external matrix, which may reduce the inherent binding capacity.