DISPOSAL OF SLAGS FROM MUNICIPAL SOLID-WASTE INCINERATORS AND HEAVY-METALS RELEASE

The problems associated with the possible use of slags from municipal solid waste incinerators as secondary raw material, for instance, in roadbeds, are related to their potential detrimental impact on the environment. The purpose of this study is thus the investigation of the release of several heavy metals over time by performing serial batch extractions with the periodic renewal of the liquid phase in contact with the solid phase. Three variables are taken into account: pH, contact time, and solid-solvent ratio. The results indicate that heavy metals leach differently and this is not related to pH. From a practical point of view, the contact time that is used to simulate the heavy metal release should be as short as possible, with a frequent renewal of the liquid phase. By periodically renewing the liquid phase in contact with the solid phase, it was observed that the higher the dilution, the greater the solubility of other components. Consequently, the release of Zn, Al, and Cr by progressive dilution is increased. © 1992.