Biosorption of Cr (VI) using a bacterial biofilm supported on granular activated carbon and on zeolite

摘要

Two mini-columns partially filled with granular activated carbon (GAC) and/or a natural zeolite, covered by a bacterial biofilm ofArthrobacter viscosus, were used in a continuous flow system to remove Cr (VI) from solutions with initial concentration of 70 mg/l and aworking pH ranging between 4.5 and 5.5. Three different set-up’s were used: two columns in series filled GAC covered with a biofilm, twocolumns in series filled with zeolite covered with a biofilm and a column filled with GAC followed by another column filled with zeolite,both supports covered with biofilm. Comparatively, the biosorption system supported on GAC reaches similar removal values, 19%, asthe one supported on the zeolite, 18%, but when these two beds are used in combination better performances are reached, i.e. 42%removal. The maximum uptake values ranged from 0.57 mgCr/gSupport to 3.58 mgCr/gSupport. The interactions between metal ions andfunctional groups on the cell wall surface of the biomass were confirmed by FTIR. GAC was regenerated with steam draughting andreused twice. The first regeneration caused a decrease in the removal capacity of 38% and the second regeneration caused a total decreasein the removal capacity of 76%.