On-site Remediation of Soil Contaminated by Dioxins with an Indirect Heating Process

概要

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Contaminated soils with polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DFs), and coplanar polychlorinated biphenyls (Co-PCBs) were remediated by an indirect heating process. The project was carried out on site; the soil was heated at 550°C under nitrogen stream with less than 0.5% of oxygen concentration. After heating, the soil was quickly cooled by direct injection of water. The nitrogen flue gas was emitted through scrubber, HEPA filter and activated carbon filter.<BR>As a result, the dioxins removal ratio was higher than 99%, and the isomer pattern of dioxins was almost the same both before and after the decomposition treatment. On the other hand, the isomer pattern of dioxins in scrubber condensed water was significantly different from the original. This implies that dechlorination occurred during this heating process due to a relative increase of the lower chlorinated isomers. The dioxins concentration of flue gas was 1.6-3.6 pg-TEQ/m<SUP>3</SUP> and that of water treated by a membrane filter was 0.05 pg-TEQ/l.<BR>These results suggest that this process is appropriately method for soil treatment.
日本環境化学会の論文