Yutaka Dote* and Toshiro Maruyama*

*Dep. of Civil and Environmental Engineering, Miyazaki University

+ Correspondence should be addressed to Yutaka Dote:
(1-1, Gakuen Kibanadai Nishi, Miyazaki 889-2155 Japan)

Abstract

To clarify the dissolution of heavy metals from cement solidified waste under landfill layer conditions, we conducted the serial batch extraction from ground materials that were solidified with Portland cement and included cadmium and lead chloride. Distilled water or acetic acid was used as extraction solvent. The ground materials were intermittently exposed to air or 50% of CO2 between the extraction. The dissolution of cadmium followed the hydroxide/carbonate solubility equilibrium, although the dissolution of lead did not. When the ground materials were put in contact with a low pH solution, cadmium dissolved rapidly and wholly, and lead for a long period. When the ground materials were exposed to CO2, both of the metals formed carbonates; cadmium dissolved for a long period, and lead scarcely at all. These results showed that the landfilling of cement solidified wastes over incineration residues and incombustible wastes was effective to avoid heavy metal leaching.

Key words: cement solidified waste, chemical equilibrium, serial batch extraction, cadmium, lead