Effect of Accelerated Aging of MSWI Bottom Ash on the Leaching Mechanisms of Copper and Molybdenum

• Published in: Environmental science & technology Vol. 40; no. 14; pp. 4481 - 4487
• Main Authors: Dijkstra, Joris J, Van Zomeren, André, Meeussen, Johannes C. L, Comans, Rob N. J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.07.2006
• Subjects: Adsorption; Aging; Aluminum; Aluminum Oxide - chemistry; Applied sciences; By products; carbonation; complexation; Copper; Copper - chemistry; Exact sciences and technology; Ferric Compounds - chemistry; fulvic-acid; humic substances; Hydrogen-Ion Concentration; Incineration; Incinerators; ion-binding; Iron; Leaching; Molybdenum - chemistry; Municipal solid waste; natural organic-matter; Other wastes and particular components of wastes; Pollution; speciation; surface; trace-elements; Wastes; Cinders; Organic matter; Pollutant behavior; Treatment residue; Urban waste; Environmental factor; Molybdenum; Heavy metal; Waste management; Incineration plant; Upgrading; Risk assessment; Environment impact; Waste reuse; Solid waste; Artificial ageing; pH; Lixiviation; Phase partition; Fulvic acid; Copper
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es052214s

The effect of accelerated aging of Municipal Solid Waste Incinerator (MSWI) bottom ash on the leaching of Cu and Mo was studied using a “multisurface” modeling approach, based on surface complexation to iron/aluminum (hydr)oxides, mineral dissolution/precipitation, and metal complexation by humic substances. A novel experimental method allowed us to identify that the solid/liquid partitioning of fulvic acids (FA) quantitatively explains the observed beneficial effect of accelerated aging on the leaching of Cu. Our results suggest that iron/aluminum (hydr)oxides are the major reactive surfaces that retain fulvic acid in the bottom ash matrix, of which the aluminum (hydr)oxides were found to increase after aging. A new modeling approach, based on the surface complexation of FA on iron/aluminum (hydr)oxides is developed to describe the pH-dependent leaching of FA from MSWI bottom ash. Accelerated aging results in enhanced adsorption of FA to (neoformed) iron/aluminum (hydr)oxides, leading to a significant decrease in the leaching of FA and associated Cu. Accelerated aging was also found to reduce the leaching of Mo, which is also attributed to enhanced adsorption to (neoformed) iron/aluminum (hydr)oxides. These findings provide important new insights that may help to improve accelerated aging technology.