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Effects of thermal desorption on soil structures, removal effectiveness of mercury and dioxin contam

China Petrochemical Development Corp’s (CPDC) Anshun site in Taiwan, which was highly contaminated with Hg, polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and pentachlorophenol (PCP), has received the greatest concerns globely and barely been seen in other countries. Thermal desorption has been referred to as one of the best methods for soil remediation. This technique can decontaminate the soil on-site or off-site in a short time period and possesses large removal efficiencies for organic and inorganic pollutants simultaneously. Additionally, thermal desorption was also the Phase I approach proposed by CPDC for remediating highly contaminated soils. It is imperative to note that transformation of pollutants and changes in soil properties caused by thermal treatment, however, can directly influence the subsequent utilization of treated soils. This study examines the effectiveness of thermal desorption of CPDC’s contaminated soils using a benchscale rotary reactor. The tested desorption temperature, duration, and carrier gas rate are determined based on results from thermogravimetric analysis (TGA). The contents of Hg, PCDD/Fs, and PCP of treated samples are further evaluated. We also evaluate the homologue amounts of PCDD/Fs and speciation of Hg using sequential extraction method to better understand the repartitioning of soil contaminants. The data from this study may optimize the thermal desorption parameters of soil decontamination as well as providing an insight into increasing the effectiveness of thermal treatment processes in pilot- and full-scale operation.
thermal desorption, mercury, dioxin, soil, thermogravimetry