Leaching is the release of a substance from a material or product into water or an aqueous solution. Such substances can be potentially toxic metals (e.g. As, Cd, Hg, Pb) or organic micropollutants (e.g. polyaromatic hydrocarbons PAH, polychlorinated biphenyls PCB). In the 1980s standardized leaching tests have been developed to determine the release of potentially harmful substances from waste in disposal sites to assess the potential risk to groundwater contamination. Over the years the need for more detailed information on release behaviour of the potentially hazardous nature of waste increased. The incentive to avoid the disposal of potentially useful raw materials, increase the recovery of valuable materials due to scarcity of primary materials and limit the space for permanent disposal has only increased the need for better understanding of release controlling processes with emphasis on the long-term behaviour under realistic exposure conditions. When former waste materials are utilized as alternative raw materials in construction products, it is important to understand what the environmental implications on the long term are. Particularly, when multiple cycles of use are foreseen and distinction between virgin materials and alternative raw materials cannot be made anymore.
This website aims to inform the reader about the availability and suitability of standardized leaching tests to solve their questions. It focusses on interrelationships between existing leaching tests to improve understanding of the meaning of a test result. In addition, it provides information on characteristic leaching behaviour of a range of bulk material streams, for which leaching information may be sought to compare one’s own material of product. For these materials, detailed information on release controlling minerals and sorption reactions is made available to understand possible changes in release behaviour due to changing exposure conditions between the laboratory test and actual field conditions. Guidance on the use and interpretation of leaching test is provided. Regulatory aspects, uncertainty issues and the role of the leaching tests and associated geochemical modelling in assessing potential environmental impact are addressed. Reference to relevant literature is made and access to grey literature, which is often very relevant but not easily accessed, is provided in the form of a download section.
