Behavior of dioxin during thermal remediation in the zone combustion process.
In the previous study, a new process concept for the thermal remediation of particulate/powder materials contaminated by polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) has been verified. It leads to removal efficiencies of more than 99.9% in the soil contaminated by PCDD/Fs in terms of toxicity equivalent quantity (TEQ). However, details of the reactions and phenomena during the process, i.e., decomposition, vaporization, reformation and trap of PCDD/Fs and their relating compounds, have not sufficiently been clarified yet. The present study aims to examine experimentally the transport and fate of PCDD/Fs in the process. In the experiment, a laboratory-scale process simulator and a soil sample preliminary mixed with octachlorinated dibenzo-p-dioxin spiked by carbon-13 isotope (13C-OCDD) were used. The distribution of 13C-OCDD in the soil bed during the process was measured by applying a quench technique that rapidly cools-down the bed. Further, the total amount of 13C-OCDD discharged with outlet gas was measured. Using the obtained data, mass balance of 13C-OCDD in the process was estimated. The results show that about 99% of 13C-OCDD preliminary admixed with the soil was decomposed rather than released to the outlet gas. Only a trace amount of 13C-OCDD remained in the treated soil. In addition, a very small amount of other congeners having the 13C-cycles was detected in the treated soil and outlet gas although its TEQ values are not significant. These were probably formed by dechlorination reactions occurring in the process.
Harjanto
Sri
S
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Sendai, Japan.
Kasai
Eiki
E
Terui
Toshikatsu
T
Nakamura
Takashi
T
D001572:Benzofurans / Q000032:analysis* / Q000737:chemistry; D002247:Carbon Isotopes / Q000032:analysis; D000072338:Dibenzofurans, Polychlorinated; D004787:Environmental Pollution / Q000517:prevention & control; D005740:Gases; D017745:Incineration; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis* / Q000737:chemistry; D012037:Refuse Disposal / Q000379:methods*; D012989:Soil Pollutants / Q000032:analysis*
D001572:Benzofurans; D002247:Carbon Isotopes; D000072338:Dibenzofurans, Polychlorinated; D005740:Gases; D000072317:Polychlorinated Dibenzodioxins; D012989:Soil Pollutants