Chemical Stabilization of Municipal Solid Waste Incineration Fly Ash without Any Commercial Chemicals: First Pilot-Plant Scaling Up

For the first time in Europe, results of chemical stabilization of municipal solid waste incineration (MSWI) fly ash, realized as a pilot plant, are reported. The stabilization technology is based on the use of only waste and byproduct materials (such as coal fly ash, flue gas desulfurization residues, and rice husk ash). In the frame of the COSMOS-RICE project, a pilot plant was built in Italy, with a capacity of more than 0.5 tons of MSWI fly ash/day. The stability of the material obtained was investigated by the evaluation of the pH dependency of the leaching of metals, 6 months after the treatment. The pH dependence of heavy metal solubility was described in terms of unified leaching curves, comparing first-time leaching data of MSWI fly ash from different geographical locations (Italy, Portugal, Denmark, and China), using a polynomial function. Results confirmed that COSMOS-RICE technology can be a promising path for obtaining a stabilized product with likely practical applications, avoiding costly and unsustainable landfilling.