Determinazione dell’ecotossicità di scorie da combustione mediante Trasformation and Dissolution test

The waste-to-energy plant provides clear advantages in terms of disposal and energetic requalification of wastes but, from now on, it still generates residues that must be stored in landfills. In fact, in Europe alone more than 30 million tons of wastes are incinerated every year, pfor each ton of burned waste, araound 200-300 Kg of waste slags and about 30-60 Kg of ashes are generated. Usually the ashes aren’t reused, while the slags can be further processed for further applications, such as the extraction of important metals ( iron, aluminum and zinc) or, through physical- chemical treatment, for the production of concrete instead of sand and gravel or as a filler beneath road surface. However, these slags contain heavy metals and other toxic elements in several quantities, so it’s very important to characterize their composition and releases in order to avoid any danger for the environment and humans. To do so, we resort to the transformation and dissolution test (T/D) that allows studying the releases of sparingly soluble inorganic metal compounds (SSIMS) through an acqueous matrix specifically designed to resemble meteoric water, which over time may modify the SSIMS in soluble species. The metals concentrations obtained through the test are compared with their tabulated ecotoxicity value (ERV) in order to determine the correct hazard category. To confirm the evaluation of the hazard category, ecotoxicity tests with daphnia and algae are also carried out. In this thesis, I present the T/D test and ecotoxicity test on slag samples and evaluate their hazard category confronting the results from both the tests.