Biological removal of heavy metals from acid wastewaters

摘要

Living cells of Sphaerotilus natans strain have been employed in the heavy metals removal (copper and cadmium) from acid wastewaters. Batch experiments have been carried out at starting acid conditions (pH 3.5) in order to simulate the industrial wastes characteristics. At metal initial concentration (50 mg/l) the used biomass is able to remove 80-90percent of metals and the initial pH value that is about 3.5 increases up to 7.5, corresponding to the maximum metal adsorption. Further experiments were carried out by lyophi-lised biomass in order to evaluate the pH effect, namely 4,5 and 6, on the metals removal. The use of lyophilised biomass is justified by two practical advantages: to have available biomass immediately and accurately measurable amount in the equilibrium tests. The obtained data are here compared and discussed.