不飽和汚染土壌への動電学的手法の適用に関する研究

Abstract

Electrokinetic soil remediation can be used a remediation tool to extract dissolved ions and organic compounds from soils. To initiate electrokinetic transport, a DC electric potential field is applied to soils. The magnitude of the transport velocity due to electromigration and electroosmosis is directly related to the electric potential gradient. Most researches have been focused at the remediation of saturated soils. However, many contaminant sources lie within unsaturated soils as a result of leaking chemical storage tanks and landfills. Electrokinetic induced transport of soil water and ions within the water may provide a remediation alternative to unsaturated soils. In this study, hydrogen and cadmium ions transport in unsaturated soils are predicted with a simple numerical method in which electrical flow is coupled with hydraulic flow, and the treatment for unsaturated soils are investigated. The results obtained in this study are summarized as follows: Hydrogen and cadmium ions move downward in unsaturated soils, particularly, move significantly downward in case of upper layer of sandy/clayey soils and lower layer of clayey/silty soils. However, remediation is applied successfully to unsaturated soils by coupled electric-hydraulic gradient.