Chlorinated solvent removal using food grade surfactants: Column studies

In laboratory column studies we evaluated chlorinated solvent removal using food grade surfactant-based solubilization and mobilization systems. We used nonionic sorbitan polyethoxylate monostearate for solubilization experiments, and both bis-2-ethylhexyl sodium sulfosuccinate and sodium mono- and dimethyl naphthalene sulfonate in mobilization studies. Surfactant enhanced mobilization was shown to be more efficient than solubilization for removing tetrachloroethylene. Excellent removal efficiency was maintained even when the mobilization system was varied, demonstrating the robustness of this system for subsurface remediation. The selected food grade surfactants, however, suffered mass losses in the column, probably due to the occurrence of phase separations (e.g., formation of precipitates or liquid crystals). Thus, surfactant losses need to be minimized before using these systems in full-scale applications. This study also demonstrated that surfactant performance was influenced by a variety of factors, such as the type of microemulsion, temperature, and contaminant compositions, that must also be considered in design of field implementations.