Saadat,Mohsen

Optimization Method for Remediation of "LNAPLs"from Contaminated Groundwater

Abstract

During the previous century, water in many areas of the world has become increasingly polluted by LNAPLs (Light Non Aqueous Phase Liquids). These materials form a serious threat to our drinking water supplies. To prevent health risks for humans and damage to nature, the contaminated waters should be remediated immediately. These liquids are affected by gravitational and capillary forces moving downward and prediction of their behaviors is based on these forces. Gone down enough to reach water surface, those will accumulate on the water surface and move as a thin layer. In the case of water level fluctuations, the mobile LNAPLs can be converted to residual LNAPLs. Residual LNAPLs are liquid droplets that are entrapped in soil by capillary forces. Regarding to considerable amount of capillary forces especially in fine soils, the remediation of residual LNAPLs is very difficult and impossible in some cases. New techniques are developed to clean up LNAPL contamination, where the soil is not excavated to clean it up. The most of them are based on pump of contaminated water. In this research, we have almost done a complete review on technologies and finally chose one, suitable for deep and permeable aquifers. The technology used, dual pump recovery, is an advanced method for remediation of oil contaminants. This method is based on using of two dynamic pumps (one for water and another for oil) simultaneously. In recent years, researchers have been looking for optimizing of this technology so that it is minimized to convert mobile LNAPLs to the residual LNAPLs. In a formula, developed recently, using a linear relationship between oil and water flow rate, we can use the benefits of dual pump recovery without forming of residual LNAPLs.

To simulate of remediation process, we need a simulator. In this research we have used UTCHEM 9.3, developed in Texas University at Austin, as a comprehensive three dimensional model that works based on finite difference method. We have used only its main capabilities such as diffusion, advection and dispersion in this research and ignored adsorption, biodegradation, heat transfer, surfactants and chemical reactions. On the other hand, because the final aim of this research is optimization of remediation process, we have also chosen the >