Life cycle assessment of air-pollution-control residues from waste incineration in Europe: Importance of composition, technology and long-term leaching.

Air pollution control residues (APCr) are hazardous materials generated from municipal solid waste incineration and require appropriate management. This life cycle assessment (LCA) study investigates the environmental impacts of current and alternative management options, considering the possibility of a cascading management of APCr, where one treatment technology is followed by another. In total, 14 base case scenarios and 30 sensitivity scenarios were evaluated. The effects of APCr composition, leaching, time horizon, and uncertainties were investigated. The APCr management options with the lowest environmental impacts and the smallest uncertainties were i) backfilling of underground salt mines and ii) neutralization treatment followed by backfilling (Langøya, Norway). These options were followed by iii) scenarios that included Zn extraction, iv) cement stabilization of fresh APCr followed by landfilling and v) production of cement aggregates made from carbonated APCr followed by their utilization in construction works. Recovery of salts from APCr required further performance optimizations before being environmentally competitive with other options. Long-term leaching emissions of Zn, Cr and As were among the largest contributors to toxicity-related impacts, emphasizing the need for management strategies that minimize their leaching. The investigated scenarios demonstrate that increased "processing" and cascading utilization of the residues, contribute with increased uncertainty of the results compared to landfilling and may not necessarily lead to decreased environmental impacts. LCA studies of APCr management should address the full management chain, rather than just the first treatment. Overall, the results of this study were found robust, also considering potential changes in the surrounding energy system.