Investigation of Chemical Reactivity, Mass Recovery and Biological Activity During Thermal Treatment of DNAPL Source Zones

摘要

Chlorinated organic solvents, such as trichloroethene (TCE) and tetrachloroethene (PCE), are common pollutants at military and industrial facilities, and represent one of the most difficult contamination scenarios facing site managers. Such sites typically contain a source zone, consisting of dense non-aqueous phase liquid (DNAPL) existing as entrapped ganglia and/or as high-saturation pools residing above low permeability media. Due to the combination of low aqueous solubility and mass transfer limitations, DNAPL- contaminated aquifers serve as longterm sources of groundwater contamination, which may persist for decades or even centuries. To achieve substantial DNAPL mass reduction within acceptable time frames, several in situ remediation technologies have been developed, including chemical oxidation, thermal treatment, air sparging, co-solvent flushing, and surfactant flushing. Of these technologies, thermal treatment provides two distinct advantages: (a) no chemical agents are introduced into the subsurface, and (b) the potential to efficiently treat heterogeneous porous media. In situ thermal treatment technologies, such as Electrical Resistance Heating (ERH), are capable of removing substantial chlorinated solvent mass from the subsurface and may cause in situ degradation of contaminants.