Solar‐powered soil vapor extraction for removal of dense nonaqueous phase organics from soil

Abstract

Both surface and groundwater are threatened by buried waste at a number of sites because of subsurface plumes containing dense non‐aqueous phase liquids (DNAPLs), hazardous metals, and radionuclides. In this work, a novel process is explored which represents an enhancement to thermal extraction methods as well as a mobile system that is suitable for remediation of remote sites. Solar radiation is collected by modular concentrators which transfer the concentrated solar radiation to an optical waveguide (OW) transmission line consisting of low‐loss optical fibers. The OW line transmits the high intensity solar radiation to the contaminated site where the solar flux is injected into the soil for thermally enhanced soil vapor extraction (SVE). The organic compounds driven out of the soil go through off‐gas treatment. A small prototype was constructed and used to heat soil contaminated with trichloroethylene (TCE). The thermal efficiency of the solar SVE process conducted using the small scale experiment was approximately 50%. The moisture loss in the soil sample correlated to the soil heating time. Short heating times were sufficient to remove TCE from soil samples below detection limits.

Key words:

• Soil vapor extraction
• remediation
• DNAPL