Formation and transport of PCDD/Fs in the packed bed of soil containing organic chloride during a thermal remediation process

Chemosphere. 2002 Oct;49(2):217-24. doi: 10.1016/s0045-6535(02)00198-4.

Abstract

The authors previously proposed the concept of a new thermal remediation process for particulate/powder materials contaminated by polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and experimentally verified its validity on the basis of process efficiency. However, contaminees such as soils and fly ashes from waste incinerators often contain a considerable amount of other chlorides, which may act as a main source of chlorine in the formation of PCDD/Fs via thermal processes. The present study aims to examine the formation and transport of PCDD/Fs in the packed bed of soil containing a chloride during the process. Polyvinyl chloride (PVC) polymer was mixed with soil sample as an organic chloride model. A laboratory-scale apparatus was employed as a process simulator. Further, a technique to quench the process was applied to observe the concentration distribution of PCDD/Fs in the solid bed in the vertical direction. The result shows that the PCDFs tend to form dominantly in the high temperature (calcination and/or combustion) zone and are successively trapped in the low temperature (wet) zone. Especially, TeCDF is the most dominant homologue contained in the wet zone and outlet gas. Although PCDD/Fs are once trapped at the wet zone, the concentration of the remediated materials gives fairly low value (1.9 pg/g-dry, 0.04 pg-TEQ/g-dry). It signifies that organic chlorides mingled in the solid contaminee not affect the removal efficiency of PCDD/Fs in the process. Nevertheless, attention should be paid to the potential emission of PCDD/Fs in the outlet gas due to the presence of organic chloride in the soil.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzofurans / analysis*
  • Chlorides / chemistry*
  • Conservation of Natural Resources
  • Dibenzofurans, Polychlorinated
  • Environmental Pollution / prevention & control*
  • Incineration
  • Polychlorinated Dibenzodioxins / analogs & derivatives*
  • Polychlorinated Dibenzodioxins / analysis*
  • Refuse Disposal
  • Soil Pollutants / analysis*
  • Temperature

Substances

  • Benzofurans
  • Chlorides
  • Dibenzofurans, Polychlorinated
  • Polychlorinated Dibenzodioxins
  • Soil Pollutants