LEACHING BEHAVIOR OF POLLUTANTS IN STABILIZED SOLIDIFIED WASTES/

The objective of the study is to characterize pollutant retention in w astes solidified with hydraulic binders in order to predict the long t erm leaching behavior. The stabilized/solidified wastes are APC MSW (a ir pollution control residues from municipal solid waste incineration) , lead secondary smelting slag and different salts. The binders used a re ordinary Portland cement (OPC 55) or blast furnace slag cement (CLK 45) and additives, such as melakaolin. Leaching tests are used in the characterization procedure. Modelling of the observed leaching behavi or is conducted to improve the description of the physical and chemica l phenomena involved in the release of soluble species. The main resul ts of the study allow a distinction to be made between the species who se solubility is not sensitive to the chemical context of the porewate r, and the other species, such as amphoteric metals, whose solubility is sensitive to the context (especially the pH). In the first case, a diffusion or shrinking front model is appropriate. In the second case, a coupled solubilization/diffusion model must be developed in order t o describe the leaching behavior of heavy metals (lead, etc.) containe d in the stabilized/solidified wastes. (C) 1997 Elsevier Science B.V.