METALS DISTRIBUTION IN SOLIDIFIED STABILIZED WASTE FORMS AFTER LEACHING

A series of leach tests were conducted to study the metal distributions in cement-based waste form before and after leaching in acetic acid solutions. The specimens were prepared in the laboratory with a Type I portland cement and sludges containing high levels of lead, cadmium, and arsenic. Metal contents in the specimen were determined by both the SEM/EDX method and the Wet digestion/AA method. A kernel surrounded by a surface layer was observed in every leached specimen. In the surface layer, most of the calcium and the stabilized metals (Pb, Cd, and As) were removed by the leachants. The metal contents of the kernel, however, were very close to those of the original material.