FINITE-ELEMENT MODELING ON THE CONVECTIVE TRANSPORT OF AN ORGANIC SOLVENT THROUGH NONUNIFORM SOILS DURING IN-SITU PHOTOLYSIS PROCESS

Lee, Kun Sang

doi:2003.8.3.122

Environmental Engineering Research 2003;8(3): 122-129. DOI: https://doi.org/10.4491/eer.2003.8.3.122

FINITE-ELEMENT MODELING ON THE CONVECTIVE TRANSPORT OF AN ORGANIC SOLVENT THROUGH NONUNIFORM SOILS DURING IN-SITU PHOTOLYSIS PROCESS

Kun Sang Lee^†

Division of Civil and Environmental Engineering Kyonggi University, Suwon, Kyonggi 442-760, Korea

Corresponding Author: Kun Sang Lee ,Tel: +82-31-249-9738, Fax: +82-31-244-6300, Email: kslee@kyonggi.ac.kr

Received: February 9, 2003; Accepted: April 10, 2003.

ABSTRACT

In-situ photolysis of a nonuniform soil containing 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been theoretically analyzed to develop a numerical model and gain further insight for the physical process involved. This study focuses on the mathematical description and the development of a finite-element model for the convective upward transport of an organic solvent driven by photodecomposition at the surface. The model includes the effects of size and its distribution of soil particles, physicochemical characteristics between soil surface and solvent, and initial saturation on the transport velocities through the unsaturated soil zone. Extensive numerical calculations were performed to yield the profiles of saturation in the simulated nonuniform porous media. For uniform media, larger value of initial saturation results in larger amount of evaporation at the surface. The effect of pore size is almost negligible. For nonuniform media, the effects of nonuniformity become significant as pore size and initial saturation become smaller. Larger initial saturation and smaller pore size lead to a larger variation of saturation with the lowest value at the surface. The simulation studies conducted in this study have shown that the developed model is very useful in analyzing the effects of physical and chemical characteristics on the decontamination process in the soil environments.