IMMOBILIZATION OF HEAVY-METALS IN A POLLUTED SOIL OF A SEWAGE FARM BYAPPLICATION OF A MODIFIED ALUMINOSILICATE - A LABORATORY AND NUMERICAL DISPLACEMENT STUDY

The efficiency of the modified alumino-silicate ''Berengite'' to fix h eavy metals in contaminated soils was studied using a soil from a form er sewage disposal site with high loads of Zn and Cd. The immobilizati on effects for different additions of Berengite were described on the laboratory scale with the cation exchange capacity and a two component Freundlich sorption isotherm. Long term displacement of Cd and Zn wer e calculated with a numerical simulation model. The simulation studies show a rather high immobilization of Zn and Cd in the solid phase for the next 80 years. Far more Berengite is required for the fixation of Cd than for Zn.