Grantee Research Project Results
1998 Progress Report: Investigation of the Entrapment and Surfactant Enhanced Recovery of Nonaqueous Phase Liquids in Heterogeneous Sandy Media
EPA Grant Number: R825409Title: Investigation of the Entrapment and Surfactant Enhanced Recovery of Nonaqueous Phase Liquids in Heterogeneous Sandy Media
Investigators: Abriola, Linda M. , Pennell, Kurt D. , Dane, Jacob H.
Institution: University of Michigan , Auburn University Main Campus , Georgia Institute of Technology
EPA Project Officer: Hahn, Intaek
Project Period: November 1, 1996 through October 31, 1999
Project Period Covered by this Report: November 1, 1997 through October 31, 1998
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
Objective:
The primary objectives of this research project are: 1) to investigate the influence of scale and formation heterogeneity on the entrapment and surfactant-enhanced recovery of NAPLs in two-phase sandy aquifer systems; and 2) to refine and validate numerical simulators which may be used for the design and prediction of surfactant enhanced aquifer remediation (SEAR) performance at the field scale.Progress Summary:
Progress in each of the four task areas includes: (1) measurement of fundamental fluid properties and solubilization capacities and completion of one-dimensional column experiments for the quantification of solubilization rate limitations; (2) refinement and adaptation of numerical models for two-phase NAPL migration and entrapment and surfactant-enhanced recovery; (3) experimental and numerical investigation of NAPL infiltration and entrapment processes in small and large-scale 2D tanks; and (4) experimental and numerical investigation of surfactant enhanced solubilization of NAPL in 2D sank tanks.Laboratory studies have been conducted to measure and characterize fundamental surfactant and NAPL properties, including density, viscosity, and interfacial tension, for PCE and surfactant/cosolvent solutions. The influence of ethanol addition on solution density and viscosity was also explored. Kinetic batch tests were completed to measure PCE solubilization capacities for a variety of surfactant/cosolvent mixtures. A series of one-dimensional column experiments was conducted to quantify the influence of rate-limited solubilization on PCE recovery efficiency in porous media.
Experiments in large scale, highly monitored, 2D laboratory sand tanks were conducted to investigate the influence of macroscale heterogeneities on two-phase NAPL migration and entrapment and the use of partitioning tracers for NAPL residual characterization. As anticipated, the macro-heterogeneities were observed to considerably influence PCE migration pathways. Data are currently being analyzed for future comparisons with model simulations.
Experiments were also conducted in smaller scale sandboxes to investigate the migration and entrapment of PCE under different interfacial conditions and to explore the solubilization of entrapped PCE by a 4% Tween 80 solution in 2D heterogeneous sandy media. In the former experiments, interfacial tension was demonstrated to have a major influence on PCE migration pathways in heterogeneous systems. In the latter experiments, excellent SEAR performance was observed, with the majority of residual PCE being removed within five pore volumes.
The sandbox experiments were simulated using independently measured or estimated parameters, to provide a test of the predictive capabilities of mathematical models. Numerical predictions of PCE infiltration pathways were qualitatively similar to visual observations of PCE migration. Quantitatively, however, the simulations did not accurately predict the rate of migration and tended to over-predict the extent of NAPL spread. Some of these discrepancies are likely the result of inadequate grid resolution, which has been shown to have substantial influence on numerical predictions of multiphase flow. For the solubilization experiments, the ability of the model to match measured effluent concentrations and total PCE recovery varied over the duration of the experiment, and appears to depend on the initial PCE distribution. The deviations between observed and predicted concentrations may be explained by differences between modeled and actual interfacial contact area or by inaccurate representation of the initial PCE distribution. Although effluent concentrations were not precisely modeled, overall recoveries were well-predicted for the majority of the entrapped PCE. These results suggest that column-measured mass transfer rates can be used successfully for the prediction of larger scale SEAR performance.
Future Activities:
Laboratory experiments in 2D sand tanks will continue for the investigation of NAPL entrapment and SEAR performance. Data obtained from the large-scale sand tank experiments will be modeled. Work will continue on the refinement of parametric models and the development of guidelines for grid resolution for prediction of NAPL migration and SEAR performance.Journal Articles on this Report : 1 Displayed | Download in RIS Format
| Other project views: | All 23 publications | 5 publications in selected types | All 4 journal articles |
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Rathfelder KM, Abriola LM, Taylor TP, Pennell KD. Surfactant enhanced recovery of tetrachloroethylene from a porous medium containing low permeability lenses: 2. Numerical simulation. Journal of Contaminant Hydrology 2001;48(3-4):351-374. |
R825409 (1998) R825409 (1999) R825409 (Final) |
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Supplemental Keywords:
RFA, Scientific Discipline, Toxics, Waste, Ecosystem Protection/Environmental Exposure & Risk, Remediation, Environmental Chemistry, HAPS, Chemistry, Fate & Transport, Hazardous Waste, Hazardous, Environmental Engineering, SEAR technology, fate and transport, fate and transport , NAPL, contaminant transport, surfactant enhanced aquifer remediation, transport contaminants, dual energy gamma radiation system, chemical contaminants, pump and treat systems, geochemistry, saturated porous media, ecological impacts, hazardous chemicals, assessment methods, heterogenous sandy media, NAPLs, porous mediaProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.