1 Scope
This Technical Specification is applicable for determining the leaching behaviour of monolithic wastes under dynamic conditions. The test is performed under experimental conditions relevant to assess the leaching behaviour in view of the considered scenario(s). This test is aimed at determining the release as a function of time of inorganic constituents from a monolithic waste, when it is put into contact with an aqueous solution (leachant).
In general, the composition, the temperature and the continuous renewal rate of the leachant are chosen such that the leaching behaviour of the waste material can be studied in view of the considered disposal or recovery scenario. When the release is to be determined without any reference to a specific scenario, the leachant is demineralised water, the temperature and the continuous renewal rate are fixed.
This dynamic monolithic leaching test (DMLT) is a parameter specific test as specified in EN 12920 and is then not aimed at simulating real situations. The application of this test method alone is not sufficient for the determination of the detailed leaching behaviour of a monolithic waste under specified conditions.
In the framework of EN 12920 and in combination with additional chemical information, the test results are used to identify the leaching mechanisms and their relative importance. The intrinsic properties can be used to predict the release of constituents at a given time frame, in order to assess the leaching behaviour of monolithic waste materials, placed in different situations or scenarios (including disposal and utilisation scenarios).
The test method applies to regularly shaped test portions of monolithic wastes with minimum dimensions of 40 mm in all directions that are assumed to maintain their integrity over a time frame relevant for the considered scenario. The test method applies to test portions for which the geometric surface area can be determined with the help of simple geometric equations. The test method applies to low permeable monolithic materials.
NOTE 1 If, in order to comply with the requirements of regular shape, the test portion is prepared by cutting or coring, then new surfaces are exposed which can lead to change(s) in leaching properties. On the other hand if the test portion is prepared by moulding, the surface will be dependent to the type of mould and the conditions of storage. If the intention is to evaluate the behaviour of the material core, the specimen needs to be stored without any contact with air to avoid carbonation.
NOTE 2 For monolithic waste materials with a saturated hydraulic conductivity higher than 10-8 m·s-1, water is likely to percolate through the monolith rather than flow around it. In such cases, relating the release to the geometric surface area can lead to misinterpretation. A percolation test is then more appropriate (e.g. CEN/TS 14405).
This procedure may not be applicable to materials reacting with the leachant, leading for example to excessive gas emission or an excessive heat release.
This document has been developed to determine the transfer of mainly inorganic constituents from wastes. It does not take into account the particular characteristics of organic constituents nor the consequences of microbiological processes in organic degradable wastes.
