Leaching methods for soil, sludge and treated biowaste

摘要: This desk study on LEACHING METHODS FOR SOIL, SLUDGE AND TREATED BIOWASTE has been carried out in the framework of project HORIZONTAL. It focuses on the possible development of horizontal standards on leaching of sludge, soil and biowaste. The results obtained in EU funded projects on Harmonisation of Leaching/Extraction Tests, in which leaching test methods on a wide range of matrices have been compared, have demonstrated the potential for adopting horizontal standards for characterisation leaching tests. The methods developed for waste are sufficiently generic to be applicable to sludge, soil and biowaste, as has been demonstrated in the afore mentioned EU project. The methods to be considered are a pH dependent leaching test, a percolation test and batch leaching tests for compliance purposes. In particular, the pH dependence leaching test has been identified as a tool that can be used as a basis of reference for a wide range of single step extraction methods and sequential chemical extractions used in soil and sediment studies. Recently developed geochemical modelling tools allow a quantification of the chemical speciation of contaminants in leachates, most notably the important partitioning between free and dissolved organic carbon (DOC)-bound metal in solution as a function of pH or liquid/solid ratio (percolation test). In addition, the pH dependence leaching test provides a good indication of total dissolved concentrations in pH domains relevant for plant uptake and inhalation/ingestion (bioavailability). From a comparison of (pseudo) total content and the (generally limited) metal leachability from soil …