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

The development of improved methods for remediation of contaminated subsurf ace systems has emerged as a significant environmental priority. One techno logy that appears to have considerable promise involves the use of solubili zation-enhancing agents, such as surfactants, cosolvents, dissolved organic matter (DOM), and complexing agents, to promote removal of immiscible-liqu id and sorbed phase organic contaminants. We examined the use of six flushi ng agents, i.e., two anionic surfactants, two complexing agents (cyclodextr ins), 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 in duced by these agents show that the solubility of TCE was enhanced between 3 and 57 times depending on the flushing agent. Column experiments were con ducted to compare water and agent-enhanced flushing of Borden sand containi ng residual saturations of TCE. As expected, the total flushing volume nece ssary to remove the residual saturation was reduced substantially in the pr esence of all applied agents. The relative effectiveness of the agents vari ed based on the method of evaluation. On a mass-efficiency basis, SDS outpe rformed all other agents, whereas DOM provided the best performance on a mo lar-efficiency basis. (C) 2000 Elsevier Science B.V. All rights reserved.