Solubilization and removal of residual trichloroethene from porous media: comparison of several solubilization agents

The development of improved methods for remediation of contaminated subsurface systems has emerged as a significant environmental priority. One technology that appears to have considerable promise involves the use of solubilization-enhancing agents, such as surfactants, cosolvents, dissolved organic matter (DOM), and complexing agents, to promote removal of immiscible-liquid and sorbed phase organic contaminants. We examined the use of six flushing agents, i.e., two anionic surfactants, two complexing agents (cyclodextrins), a humic acid, and an alcohol, for solubilizing and removing residual-phase immiscible liquid from porous media. The results of batch experiments conducted to measure the degree of trichloroethene (TCE) solubilization induced by these agents show that the solubility of TCE was enhanced between 3 and 57 times depending on the flushing agent. Column experiments were conducted to compare water and agent-enhanced flushing of Borden sand containing residual saturations of TCE. As expected, the total flushing volume necessary to remove the residual saturation was reduced substantially in the presence of all applied agents. The relative effectiveness of the agents varied based on the method of evaluation. On a mass-efficiency basis, SDS outperformed all other agents, whereas DOM provided the best performance on a molar-efficiency basis. (C) 2000 Elsevier Science B.V. All rights reserved.