QUALITY IMPROVEMENT OF GRANULAR WASTES BY SEPARATION TECHNIQUES

摘要

Heavy metals, organics and other compounds usually contaminate granular wastes. They have an environmental impact. On the other hand, some components in granular wastes have similar physical and chemical properties as primary raw building materials. Therefore they have potentially good perspectives for utilization in civil engineering works as secondary raw building materials. Required by the Dutch Building Materials Decree (BSB), to protect groundwater and soil, the leaching values of inorganic components and composition of organics must be under certain limits to reuse them as secondary building materials. From technical aspects, some wastes fail with respect to the physical and mechanical properties for a specific application because of unwanted components that may negatively affect the reuse or limit the application functions. From both environmental and technical aspects, it is necessary to improve the quality of granular wastes by separating undesired components. For this purpose, separation techniques are suitable to treat such materials. The selection of techniques is therefore an important step. Based on analysis of contaminants and discussion of techniques, this paper gives the rules for technique selection and quality improvement.