LABORATORY-SCALE BIOSORPTION AND DESORPTION OF METAL-IONS USING WASTESLUDGES AND SELECTED ACIDS

Waste sludges have shown potential for the removal of heavy metals fro m industrial effluents. The objective of the present research was to d evelop a novel biotechnological process for metal ion removal from con taminated industrial effluents, using waste digested sludges, through the optimisation of laboratory-scale biosorption and desorption proced ures. Synthetic metal effluents were exposed to three sludges to compa re their biosorptive capacities. After biosorption, sludge-bound metal s were desorbed using 0.2 N H2SO4, 0.4 N CH3COOH and 0.2 N HCl. The bi osorption capacities of sludges varied and their affinity for metal io ns displayed the following descending order of preference, Zn2+ > Cd2 > Cu2+ > Ni2+ > Cr3+ > Cr6+. The desorbent of choice was 0.2 N H2SO4.