THE EFFECT OF INSIDE CIRCUMSTANCE OF THE HAZARDOUS WASTE LANDFILL ON THE LEACHING BEHAVIOR OF HARMFUL HEAVY METALS

Abstract

In Japan, among three landfill classes, the hazardous waste landfill is used for disposing ofhazardous waste of which leaching of heavy metal exceeds its criteria. To prevent the emission of ahazardous substance to the surrounding environment, the hazardous waste landfill is required to beconstructed with a robust concrete wall and base, and the top must be capped. Because of the containmentstructure, rainwater infiltration and air intrusion hardly occur. This means the leaching potential of hazardousheavy metals in waste remains forever. But considering long term safety, their leaching potentials must bebetter reduced. In this study, the influence of interior condition in the hazardous waste landfill on theleaching of heavy metals was examined from the accelerated weathering experiments for dust which isdisposed of at the hazardous waste landfill. As the results, a decrease in the leaching amount of Cd, Pb, Mn,and Zn was confirmed in a wet environment where adsorbed water was present on the particle surface. Onthe other hand, in the dry and CO2 saturated environment, an increase in the leaching amount was observed.The former phenomenon was thought to be the formation of hydroxide at the particle surface, and the latterwas considered to be the influence of adsorption of CO2 to Fe3O4 and ZnO. Though further scientificverification is required for each phenomenon, the findings obtained in this study indicate that the leaching ofheavy metals from wastes in the hazardous waste landfill may change over time depending on the interiorcondition.