Surfactant enhanced remediation of contaminated subsurface by chlorinated solvents

Abstract

Contamination by organic pollutants such as chlorinated solvents in the subsurface has been a serious problem. They are very toxic to human and mostly nonbiodegradable. When the chlorinated solvents leak or spill from underground storage tanks, the liquid moves downward and accumulates in the aquifer. In case of chlorinated solvents, the liquids migrate below water table in consolidated deposits and fractured bedrock until to meet the impermeable layer which prevents the movement of the liquids and form dense nonaqueous phase liquid (DNAPL). The DNAPL is dissolved by groundwater flow and makes the aqueous phase plumes of the contaminants. Even though the concentration of contaminant is very low, the DNAPL like chlorinated solvents is highly toxic and poses an unacceptable risk to human health or the environment. Traditional treatment method for DNAPL contaminated subsurface is “pump and treat” method. But it has a serious disadvantage which is the need of very long time to complete removal. To overcome the disadvantage, surfactant enhanced aquifer remediation (SEAR, or surfactant flushing) has been developed. The SEAR is consisted with the injection of surfactant, removal of organics by dissolution and displacement, and treatment of the effluent. Most of researches on surfactant flushing focused on the solubilization of DNAPL and few researches have dealt with the surfactant behavior. The solubilization is based on surfactant characteristics. If we know the surfactant behavior and transport phenomena of surfactant solutions, the efficiency of solubilization of DNAPL can be expected. In this study, interaction between surfactants and DNAPLs was mainly observed by means of partitioning of surfactants. Additionally the treatment of effluent of surfactant flushing also was investigated by activated carbon adsorption and cross-flow ultrafiltration. In the surfactant flushing, two factors, the partitioned amount of surfactant to DNAPL and solubilization capacity...