MODELING OF SOIL VENTING PROCESSES TO REMEDIATE UNSATURATED SOILS

A multicomponent, nonisothermal model to predict the evaporation rates of organic contaminants in unsaturated soils during soil venting is presented. This model can account for temperature variations in the soil due to heat absorbed during the evaporation and due to provision of heat sources to enhance soil remediation. The model assumptions were verified by one-dimensional column experiments. Experimental results indicated that the venting air is saturated with the contaminant vapor even at high air flow rates. Local temperatures in the soil were found to decrease significantly, during venting of volatile contaminants with relatively high latent heat of vaporization. Condensation of water vapor from the incoming air is found to affect the evaporation rates of the contaminant and the temperature profiles in the soil. Model predictions were in good agreement with the experimental data. The numerical code is used to parametrically study the effects of contaminant volatility and latent heat absorbed during evaporation on the remediation times. Remediation times were found to be underpredicted by isothermal models. It was found that heating the inlet air can enhance remediation only for less volatile contaminants.