Geochemical speciation modeling

Understanding the controlling factors for release is crucial for long-term prediction of release. Chemical speciation modelling is a key element in obtaining such understanding. Saturation indices of potentially solubility controlling minerals in soil, sediments, wastes and construction materials can be calculated with geochemical modelling environment ORCHESTRA embedded in LeachXS. For modellong of metalbinding by DOC the NICA-Donnan model is applied. The development of a database/expert system, in which material data are grouped in a systematic way, opens the possibility of instantaneously coupled geochemical modelling, thus saving substantial time and effort. As example modelling data for Zn leaching from Municipal solid Waste Incinerator Bottom ash is given for both pH dependence leaching tests data and percolation test data illustrating the potential relevance of the Zn mineral willemite (ZnSiO4) as controlling phase. Based on this identfication of potential minerals the results from the pH dependence test (TS14429) can be modelled (chemical speciation fingerprint).