Abstract
The impact of natural weathering on the behavior of Fe-rich phases, their transformation, and the formation of the relevant secondary products in the weathered bottom ash samples of a municipal solid waste incineration (mono) landfill site in the northeast USA were systematically investigated. Samples of various ages (1-20 yrs) were collected from four locations of the landfill in 2009. Optical microscopy, SEM-EDX, XRD and XRF examinations were applied in order to document the footprints of weathering processes. Use of these techniques revealed that several secondary products (amorphous or crystalline) have been developed, including goethite (α-FeOOH), lepidocrocite (γ-FeOOH), hematite (Fe2O3), magnetite (Fe3O4), iron oxide (FeO), and Fe-rich Ca-Si and Ca-Al-Si gel phases. They occurred under variable environmental conditions as the weathering products of primary iron-bearing phases that usually exist in incineration ash. The strong affinity of these secondary phases with heavy metals of environmental significance such as Zn, Cu, Pb, and Ni was also identified. This suggests that the development of secondary Fe-rich products can partially contribute to the reduction of heavy metals released into the surrounding environments.
