Release behaviour of MSW-incineration bottom ash after artificial ageing

One of the technologically simplest processes applicable to promote the transformation of bottom ash constituents into a less soluble and more thermodynamically stable forms is accelerated weathering, known also as artificial ageing. This treatment mimics and speeds up the natural weathering processes caused by the contact between ash and atmospheric agents (water, O2 and CO2) and consists on a series of chemical and mineralogical transformations including hydration/hydrolysis, dissolution/precipitation of hydroxides and salts, oxidation/reduction, sorption and ion exchange reactions, as well as formation of solid solutions and clay-like minerals from the glassy phase of the material (Meima and Comans, 1997; Meima and Comans, 1999; Sabbas et al., 2003). In particular, the treatment known as accelerated carbonation simulates the natural weathering processes occurring due to prolonged contact with atmospheric CO2 during temporary storage, utilization or final disposal of incinerator residues.