Numerical and Experimental Investigation of Steam Stripping of Lnapl-Contaminated Soils

Steam injection is an example of thermal remediation technology which involves the injection of steam into the sub-surface and simultaneous recovery of fluids from extraction wells. The injected steam heats the soil and created a steam zone that expands from the injection wells as more steam is injected. The main objective of the research work was to carry out numerical modeling and laboratory experiments in order to evaluate the effectiveness of steam injection for remediation of soils contaminated with Light Non Aqueous Phase Liquids (LNAPLs). MATLAB (Matrix Laboratory) package was used for the numerical modeling while the experimental aspect involved the injection of dry steam produced from a boiler into a sand column which contain a saturated mixture of LNAPL contaminant (i.e. Kerosene) and sample of sand (two samples of sand were used; fine and coarse grain sand). As steam was introduced into the column, the viscosity of the contaminant reduces due to increase in temperature which makes the contaminant to flow and was recovered at the base of the set-up over time. It was discovered that increase in pressure and the soil grain size increases the LNAPL flow rate and reduces the time of treatment. Also the sand grain size affect the recovery rate and efficiency as well as the time of treatment for possible clean up to be achieved. Steam injection was found to be about 80-85% efficient in the removal of LNAPL contaminants from contaminated soil. The result has therefore demonstrated the effectiveness of steam injection process as a thermal soil remediation technique.