Evaluation of a countercurrent biosorption system for the removal of lead and copper from aqueous solutions

Abstract: An automated bench-scale countercurrent biosorption system (CBS) has been designed for the removal of metals from aqueous effluents. The system has been tested with activated sludge microorganisms as a biosorbent and lead and copper as model metals. Nearly 5 1 of a lead nitrate solution at 100 mg l⁻¹ of lead have been treated down to a final concentration of 0.1 mg l⁻¹ (99.9% removal) by using 4.8 g of dry biosorbent. Under similar conditions, copper chloride solutions at 100 mg 1⁻¹ of copper were treated down to a final concentration of 35–45 mg l^−l representing 60% removal. The advantage of the CBS is to maximize metal concentration in the biosorbent, from which the metal may thereby be recovered if desired. In addition, the CBS minimizes metal concentration in the treated effluent, which is the first objective of the treatment.