BIOSORPTIVE FLOTATION IN METAL-IONS RECOVERY

Heavy metals can be removed from dilute aqueous solutions in many ways . Among the innovative ones may be classified a process consisting of biosorption followed by flotation. A metal cation, cadmium, was examin ed; the metal was abstracted by microorganisms belonging to the Actino mycetes, i.e., Streptomyces clavuligerus and Streptomyces griseus, whi ch have a filamentous morphology, and hence present a flocculent chara cter. Dissolved-air flotation was the technique applied on a laborator y scale without the addition of any flotation surfactant. The paramete rs investigated in the batch mode were contact time, recycle ratio, so lution pH, Cd concentration, biomass addition, and use of a frother (e thanol). Promising results were obtained; in certain cases an almost q uantitative cadmium abstraction, followed by higher than 90% biomass r ecovery, was found.