Anionic surfactant remediation of soil columns contaminated by nonaqueous phase liquids

A variety of column experiments have been completed for the purpose of sele cting and evaluating suitable surfactants for remediation of nonaqueous pha se liquids (NAPLs). The various NAPLs tested in the laboratory experiments were tetrachloroethylene (PCE), trichloroethylene (TCE), jet fuel (JP4) and a dense nonaqueous phase Liquid from a sire at Hill Air Force Base, UT. Bo th Ottawa sand and Hill field soil were used in these experiments, Surfacta nt candidates were first screened using phase behavior experiments and only the best ones were selected for the subsequent column experiments. Surfact ants which showed high contaminant solubilization, fast coalescence times, and the absence of liquid crystal phases and gels during the phase behavior experiments were tested in soil column experiments. The primary objective of the soil column experiments was to identify surfactants that recovered a t least 99% of the contaminant. The secondary objective was to identify sur factants that show low adsorption and little or no loss of hydraulic conduc tivity during the column experiments. Results demonstrated that up to 99.9% of the contaminants were removed as a result of surfactant flooding of the soil columns. The addition of xanthan gum polymer to the surfactant soluti on was shown to increase remediation efficiency as a lower volume of surfac tant was required for recovering a given volume of NAPL. Based on these exp erimental results, guidelines for designing highly efficient and robust sur factant floods have been developed and applied to a field demonstration. (C ) 1999 Published by Elsevier Science B.V. All rights reserved.