Similarities in the leaching behaviour of trace contaminants from waste, stabilized waste, construction materials and soils

Leaching tests are carried out on a wide variety of materials for regulatory purposes, waste management, environmental impact assessment and for scientific purposes. Due to the increased concern about the environmental impact of human activities, leaching tests are being developed to answer specific questions for each of these different purposes and materials. This development could lead to the use of a wide variety of leaching tests without consideration of their interrelationships. In this work it is shown that similarities in leaching behaviour occur throughout different classes of materials. Several factors affect the leaching behaviour of waste, stabilized waste, construction materials and soils, implying that a single test will be inadequate to cover the full range of environmental properties of a material. For any type of material a limited number constituents can be identified as the key contaminants determining its environmental quality. The leachability of particular contaminants is controlled by a limited number of parameters (e.g., pH, redox potential, complexation) that may be more pronounced in one material relative to another. This would call for a more focussed approach on key contaminants and key parameters relevant for specific categories of materials. The observed similarities in the leaching behaviour of waste, stabilized waste, construction materials and soils, allow for a common approach in the characterization of leaching by focusing on the relevant contaminants/parameters in relation to quality control and regulatory testing. Such an approach will facilitate the evaluation of materials showing overlap in regulation, when materials are transformed from a usable product into a waste and when waste materials are made suitable for reuse/recycling.