Metal ion accumulation by immobilised cells of Brevibacterium sp

This paper explores the use of an experimental system based on polyacrylamide-entrapped cells of Brevibacterium sp strain PBZ for the removal of metal ions from solutions. Experiments were performed in columns filled with the immobilised cells and challenged with influents containing 20 mg L⁻¹ of lead and 10 mg L⁻¹ of cadmium. The cells were able to accumulate lead (about 40 mg g⁻¹ dry biomass) and, to a lesser extent, cadmium (about 13 mg g⁻¹ dry biomass) from solutions. In the presence of 0.4 g L⁻¹ of glucose, the cells removed up to 53% of lead. Lead competed with cadmium for attachment to the binding sites when a solution containing both the metals was applied. Lead removal occurred by a combination of fast physico-chemical adsorption and prolonged low rate accumulation mediated by cell metabolism. The biosorptive capacity of the cells was sensitive to pH. Desorption of the metal with EDTA restored the binding capability of the cells.