Remediation of groundwater contaminated with chlorinated solvents using vegetable oil emulsion

Abstract

Emulsion-based remediation technology was proposed as an alternative for SEAR (surfactant-enhanced aquifer remediation). This study focused on application of vegetable oil emulsion to the removal of chlorinated solvents, the representative of DNAPLs (dense non-aqueous phase liquids), from groundwater. Corn and olive oil were used as the emulsifying agent. Emulsion was prepared by mechanical homogenization of oil solution. Trichloroethylene (TCE) and tetrachloroethylene (PCE) were selected as a target contaminant. The emulsification conditions were determined as homogenization at 8,000 rpm during 15 min. The emulsion droplets prepared with corn and olive oil showed similar size distribution in the range of 1 - 10 μm. More than 90 % of oils initially injected existed as dispersed state. In the batch experiments, 2 % (v/v) corn and olive oil emulsion could effectively treat 11,000 ppm TCE and 18,000 ppm PCE without making free phase. Removal efficiency was higher in PCE than in TCE because solubility of PCE on oil was higher than that of TCE. Results of one-dimensional column flushing indicated that the contaminant of high aqueous solubility could be well removed by flushing. The removal efficiencies in flushing were 98.2 % for TCE and 98 % of PCE with corn oil emulsion and 99.1 % for TCE and 98.7 % for PCE with olive oil emulsion. The results of this study show that flushing with oil emulsion can be applied to treat the chlorinated contaminants.