THEORETICAL-ANALYSIS OF A METHOD FOR INSITU DECONTAMINATION OF SOIL CONTAINING 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN

Cleanup of soil contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is usually done using high-temperature incineration, but an in situ method is being developed which could be more cost-effective and less destructive to the site. This is based on the fact that TCDD can undergo photolysis by sunlight under the proper conditions. An organic solvent mixture is added to the contaminated soil, and time is then allowed for TCDD solubilization, transport, and photodegradation. These studies focus on the mathematical description of the decontamination process. The model that has been developed can be used to further optimize the cleanup conditions. This model uses two sets of equations to describe the fluid flow and the TCDD movement and photodegradation. It considers convective transport (driven by evaporation) and diffusive transport of the TCDD. Once the contaminant reaches the soil surface, it is photodegraded or it can accumulate in a film of TCDD at the surface of the column.