US EPA

Investigation of the Entrapment and Surfactant Enhanced Recovery of Nonaqueous Phase Liquids in Heterogeneous Sandy Media

EPA Grant Number: R825409
Title: Investigation of the Entrapment and Surfactant Enhanced Recovery of Nonaqueous Phase Liquids in Heterogeneous Sandy Media
Investigators: Abriola, Linda M. , Dane, Jacob H. , Pennell, Kurt D.
Institution: University of Michigan , Auburn University Main Campus , Georgia Institute of Technology - Main Campus
EPA Project Officer: Stelz, Bill
Project Period: November 1, 1996 through October 31, 1999
Project Amount: $449,938
RFA: Environmental Fate and Treatment of Toxics and Hazardous Wastes (1996) RFA Text |  Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management , Safer Chemicals

Description:

The remediation of aquifers by conventional pump-and-treat technologies is often an inefficient and costly undertaking, particularly when nonaqueous phase liquids (NAPLs) are present. The failure of this technique can be attributed, in large part, to the low aqueous solubilities of most NAPLs and their relatively slow rates of mass transfer into the aqueous phase. To overcome such limitations, surfactants have been proposed as a means for enhancing the performance of pump-and-treat systems based on their ability to increase the aqueous solubility of hydrophobic organic compounds via micellar solubilization and to mobilize entrapped NAPLs due to interfacial tension reductions. Although laboratory studies have demonstrated the capacity of surfactants to recover NAPLs from porous media, field studies conducted to date have achieved mixed results. To facilitate more effective transfer of surfactant enhanced aquifer remediation (SEAR) technologies from the laboratory to the field, this research will: (a) investigate the influence of scale and formation heterogeneity on the entrapment and surfactant-enhanced recovery of NAPLs in two-phase aquifer systems, and (b) refine and validate numerical simulators which can be used for the design and prediction of SEAR performance at the field scale. To accomplish these objectives the project has been divided into the following four tasks: (1) measurement of fundamental parameters needed to characterize NAPL solubilization and mobilization; (2) refinement and adaptation of mathematical models to describe SEAR in 2-dimensional domains; (3) assessment of NAPL infiltration and entrapment in 2-dimensional aquifer systems of varying scale and heterogeneity; and (4) evaluation of SEAR for NAPL recovery in heterogeneous 2-dimensional aquifer systems. The 2-D experiments will be conducted in rectangular aquifer models equipped with dual energy gamma radiation systems capable of measuring soil bulk density and the volumetric NAPL and aqueous phase saturations. Four surfactant formulations will be evaluated for their ability to solubilize and/or mobilize a representative LNAPL (dodecane) and DNAPL (tetrachloroethylene). Mathematical modeling will be directly linked to the experimental studies to allow for rigorous evaluation of the numerical simulators. It is anticipated that the coupled experimental and mathematical approach described herein will provide a rational, systematic means to develop the expertise required for confident deployment of SEAR technologies in the field. The results of these studies will provide critical information on system parameters governing mass transfer rates and entrapment behavior in heterogeneous porous media and lead to the development of guidelines for the appropriate selection of surfactant systems for field trials. The proposed research will also produce validated mathematical modeling tools which can be used in the design and evaluation of SEAR technologies at the field scale.

Publications and Presentations:

Publications have been submitted on this project: View all 23 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 4 journal articles for this project

Supplemental Keywords:

RFA, Scientific Discipline, Toxics, Waste, Ecosystem Protection/Environmental Exposure & Risk, Remediation, Environmental Chemistry, Chemistry, HAPS, Fate & Transport, Hazardous Waste, Hazardous, Environmental Engineering, fate and transport, SEAR technology, contaminant transport, NAPL, surfactant enhanced aquifer remediation, fate and transport , transport contaminants, dual energy gamma radiation system, chemical contaminants, ecological impacts, geochemistry, saturated porous media, pump and treat systems, assessment methods, hazardous chemicals, heterogenous sandy media, NAPLs, porous media

Progress and Final Reports:

1997 Progress Report
1998 Progress Report
1999 Progress Report
Final Report