The Effect of Methanol on the Mobilization of Tetrachloroethylene in a Water-Saturated Soil Column.
Abstract
The contamination of surface waters and groundwater by chlorinated solvents continues to be a major environmental issue. Today, the challenge to environmental engineers is not necessarily which remediation technique to use, but how to enhance the remediation technique in order to accelerate the clean-up process. The 'pump-and-treat' method for remediating organic contaminants is experimenting with the use of chemical additives to increase the efficiency rate of subsurface contaminant removal. Because of their favorable chemical properties, alcohols such as methanol are often used in conjunction with water to flush a contaminated area, and subsequently pump it to the surface for treatment. For this study, the objectives were: (1) to reconfirm the impact of a cosolvent, such as methanol, on the observed retardation of nonpolar organic solute (tetrachloroethylene, PCE) transport in a water-saturated porous medium; and, (2) to provide evidence that ineffective mixing of two inhomogeneous fluids, such as methanol and water, can negatively impact the desired cosolvent effect. For the one-dimensional laboratory column at the flowrate tested (0.745 mL/min), methanol failed to produce the hypothesized cosolvent effect. The degree of retardation of PCE did not decrease log-linearly, but instead showed no significant difference with increasing methanol fraction. Therefore, the column system, under the conditions used in this study, may have been subject to the ineffective fluid mixing potentially associated with cosolvent-water systems. However, breakthrough behavior for methanol was generally symmetric and failed to exhibit any signs of ineffective mixing. The nature of these results underscores the complexity of the problem of mixing of inhomogeneous fluids.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1996
- Accession Number
- ADA309912
Entities
People
- Richard M. Toy
Organizations
- University of California, Los Angeles