Surfactant enhanced aquifer remediation

Microemulsions became well known from about 1975 to 1980 because of their use ia "micellar-polymer" enhanced oil recovery (EOR) (35). This technology exploits the ultralow iaterfacial tensions that exist among top, microemulsion, and bottom phases to remove large amounts of petroleum from porous rocks, that would be unrecoverable by conventional technologies (36,37). Siace about 1990, iaterest ia the use of this property of microemulsions has shifted to the recovery of chloriaated compounds and other iadustrial solveats from shallow aquifers. The latter appHcatioa (15) is sometimes called surfactant-enhanced aquifer remediation (SEAR). 

Key words surfactant-enhanced aquifer remediation surfactant sorption distribution... 

Fountain, J.C. (1997). The role of field trials in development and feasibility assessment of surfactant-enhanced aquifer remediation. Water Environ. Res., 69, 188-195. 

Fountain, J.C., Starr, R.C., Middleton, T., Beikirch, M., Taylor, C., and Hodge, D. (1996). A controlled field test of surfactant-enhanced aquifer remediation. Ground Water, 34, 910-916. 

Shook G.M., Pope, G.A., and Kostarelos, K. (1998). Prediction and minimization ofvertical migration of DNAPLs using surfactant enhanced aquifer remediation at neutral... 

Surfactant-enhanced aquifer remediation for both sorbed pollutants and nonaqueous phase liquids is addressed in Chapters 9 through 13. Chapters 9 and 10 discuss the effects of surfactants on the sorption of organic contaminants to natural soil. Seok-Oh Ko and co-workers present data on the equilibrium distribution of pollutants in the presence of surfactants, whereas James Deitsch and Elizabeth Rockaway discuss how surfactants can increase... 

Dwarakanath, V. Pope, G.A. Surfactant Enhanced Aquifer Remediation in Surfactants, Fundamentals and Applications in the Petroleum Industry, Schramm, L.L. (Ed.), Cambridge University Press, Cambridge, UK,... 

Weerasooriya, V. Yeh, S.L. Pope, G.A. Integrated Demonstration of Surfactant-Enhanced Aquifer Remediation (SEAR) with Surfactant Regeneration and Reuse in Proc. Symp. ACS Surfactant-Based Separations, Recent Advances, American Chemical Society Washington, DC, 1998. 

Battelle Duke Engineering, Surfactant-Enhanced Aquifer Remediation (SEAR) Design Manual, Technical Report TR-2206-ENV, Naval Facilities Engineering Command Washington, April 2002. 

A new dimensionless number called the trapping number has been defined it includes both gravity and viscous forces (UTCHEM-9.0, 2000). The dependence of residual saturations on interfacial tension is modeled in UTCHEM as a function of the trapping number. This is a formulation necessary to model the combined effect of viscous and buoyancy forces in three dimensions. Buoyancy forces are much less important under enhanced oil recovery conditions than under typical surfactant-enhanced aquifer remediation (SEAR) conditions therefore, it had not been carefully considered under three-dimensional surfactant flooding held conditions. 

As there are other less sophisticated and less expensive techniques available, surfactant-enhanced aquifer remediation will only be useful for decontamination of LNAPL sites in special cases. However, applicable techniques are still needed for DNAPL sites and microemulsion techniques are really promising. Therefore, most research has concentrated on this type of contaminant in recent years. Integrated concepts have been developed including aspects of soil properties [47, 48, 62, 63], density control [47, 48, 62-64], recovery and reuse of microemulsion components [47], biological degradation of residues of contaminants and injected compounds [48, 65] and costs [47, 48, 64, 65]. Two main approaches have been followed for developing effective surfactant systems which form microemulsions with DNAPL, but do not mobilise the liquid contaminant into deeper... 

References to large-scale surfactant-enhanced aquifer remediation can be found in the literature [75, 76]. Childs et al. also report results from the test site at Dover Air Force Base, Delaware [76]. Large data sets are also available from field tests at Hill Air Force Base, Utah [47, 77, 78]. Other field tests were performed at the Canadian Forces Base, Borden [51, 53], Ontario, the Bachman Road site at Oscoda [79, 80], Michigan, as well as Camp Lejeune, North Carolina [81], Traverse City Coast Guard Base, Michigan [54], Spartan Chemical Company Superfund Site, Michigan [82] and the former Naval Air Station Alameda, California [82, 83]. In the latter case a 97% extraction of DNAPL is reported [83]. 

Surfactant-enhanced aquifer remediation is relatively expensive. Thus, waste reduction or the reuse of at least a considerable part of the microemulsion components is interesting. 

Holzmer, F.J., Pope, G.A. andYeh, L. (2000) Surfactant-enhanced aquifer remediation of PCE-DNAPL in low permeability sands. In G.B. Wickramanayake, A.R. Gavaksar and N. Gupta (eds), Treating Dense Nonaqueous Phase Liquids (DNAPLs) Remediation of Chlorinated and Recalcitrant Compounds. Battelle Press, Columbus, OH, pp. 187-193. 

Weerasooriya, V., Yeh, S.L., Pope, G.A. Integrated demonstration of surfactant-enhanced aquifer remediation (SEAR) with surfactant regeneration and reuse, in Proceedings of the Symposium on Recent Advances in ACS Surfactant-based Separations, Dallas, Texas, March 29-30, 1998. 

Dwarakanath Pope Surfactant Enhanced Aquifer Remediation 435... 

Furthermore, the reduction of interfacial tension between the water and NAPL caused by the addition of surfactant reduces the effect of the capillary forces that entrap the NAPL. Both these mechanisms greatly enhance the ability of surfactants to recover trapped NAPLs from contaminated soils. Hence, surfactant enhanced aquifer remediation (SEAR) is a very promising technology for remediating NAPL-contami-nated soils. 

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