Treatment of MSWI Residues for Utilization as Secondary Construction Minerals: A Review of Methods

Abstract

Municipal solid waste incineration (MSWI) residues display a potential for reuse in construction. A risk of harmful emissions to the environment and negative effects on the performance of residues during utilization exist because of their composition. Extraction and stabilization pre‐treatment methods are available to decrease harmful leaching from utilized MSWI residues. Extraction procedures remove pollutants in a liquid phase that has to be handled as waste water. To remove fines and easily soluble chlorides and sulphates from residues, washing with water seems to be sufficiently effective. Such washing could also improve the technical properties of the final product. Using acids or chelating agents that, however, increase treatment costs enhances metal removal. For metal stabilization in the MSWI residue matrix, a multitude of processes are available, such as cement solidification/stabilization, weathering, carbonation, thermal treatment as well as chemical treatment with chelating agents, ferrous sulphate and phosphate. Sorption onto Al‐ and Fe‐(hydr)oxides seems to be most effective for stabilization of elements forming oxyanions, e.g. Mo and Sb. Despite numerous research activities, the level of treated MSWI residues is low and data on operational costs are lacking. Before implementing a full‐scale MSWI residue treatment, a thorough cost analysis is needed.

Keywords:

• MSWI ash
• re‐use
• roads
• secondary construction mineral
• treatment
• washing

ACKNOWLEDGEMENTS

The authors would like to thank the Swedish Energy Agency (project P13099‐1), The Swedish Research Council for Environment, Agricultural Science and Spatial Planning (Formas) (project 25.0/2001‐0446), Värmeforsk (project Q4‐140), the Kempe Foundation and the Board of Technical Faculty of Luleå University of Technology for their financial support. We would also like to thank Mr. Henrik Bristav from Umeå Energi for providing useful information.