In 2017 the production of municipal solid waste in Europe-28 reached 2500 Mt, destined to recycling (48%-wt), incineration and thermal valorization (28%-wt) and landfilling (24%-wt). About 19 Mt per year of residual material, defined bottom ash, were produced by thermo-valorization plants in Europe. Physicochemical features of bottom ashes make possible their treatment through full-scale technologies. Bottom ash treatment is mostly aimed at the recycling of ferrous and non-ferrous metals (in total up to 8%-wt of bottom ash), however also the valorization of the inert fraction as building material could be an interesting opportunity. Nowadays, the main critical issue to solve for the scientific and industrial research is the valorization of the fine fraction of bottom ash, which is rich of hazardous substances and not effectively valorized by conventional methods for metals recovery.
