Fate of Cu, Cr, and As during the combustion stages of CCA-treated wood fuel particles

• A safe end-of-life management of the abundant chromated copper arsenate (CCA) preserved materials is 14 demanded for several environmental and health reasons. Thermal treatment as a disposal method will allow for efficient energy recovery and more controlled separation of the CCA elements, and potentially decrease leaching of toxic compounds into soils, lakes, and groundwater in the vicinity of landfills. However, this also leads to a potential risk of increased trace element emissions into the atmosphere. Developments in combustion science and technology have focused on decreasing emissions of particulates, sulfur and nitrogen oxides, but to fully control the fate of the trace elements through the thermal process and the subsequent flue gas cleaning process, the partitioning of these elements during combustion must be understood, especially for CCA-treated materials. The fate of the CCA elements during the different stages of combustion of impregnated wood was therefore explored. This paper compares the predicted results from chemical equilibrium modeling with results from laboratory-scale single-particle batch experiments. The results showed that a significant volatilization of arsenic was obtained experimentally, which the equilibrium calculations suggest is mainly related to the volatilization stage of combustion. The chemical equilibrium analysis showed to describe the overall behavior and fate of the three elements relatively well, since both degree of volatilization and solid phase compositions were quite in agreement between model and experimental results.

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