title: Impact of enhanced-flushing reagents and organic-liquid distribution on mass removal and mass-discharge reduction.
abstract: A series of column and flow-cell experiments was conducted to investigate the impact of non-uniform organic-liquid distribution on the relationship between reductions in contaminant mass discharge and reductions in source zone mass under conditions of enhanced-solubilization flushing. Trichloroethene was used as the model organic liquid, and SDS (sodium dodecyl sulfate) and ethanol were used as representative enhanced-flushing reagents. The results were compared to those of water-flood control experiments. Concentrations of trichloroethene in the effluent exhibited multi-step behavior with time, wherein multiple secondary periods of quasi steady state were observed. This non-ideal behavior was observed for both the water-flood and enhanced-flushing experiments. For all flow-cell experiments, the later stage of mass removal was controlled by the more poorly- accessible mass associated with higher-saturation zones. The profiles relating reductions in contaminant mass discharge and reductions in mass exhibited generally similar behavior for both the water-flood and enhanced-flushing experiments. This indicates that while the rates and magnitudes of mass removal are altered by the presence of a solubilization-reagent solution, the fundamental mass-removal process is not. The profiles obtained for the flow-cell systems differed from those obtained for the column systems, highlighting the impact of source-zone heterogeneity on mass-removal behavior.
authors.affiliation: Department of Geological Engineering, University of Kocaeli, TR-41380 Kocaeli, Turkey ; School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Building, Tucson, AZ 85721, United States.
authors.forename: Nihat Hakan
authors.initials: NH
authors.lastname: Akyol
authors.affiliation: School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Building, Tucson, AZ 85721, United States.
authors.forename: Ann Russo
authors.initials: AR
authors.lastname: Lee
authors.affiliation: School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Building, Tucson, AZ 85721, United States.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Brusseau
keywords: DNAPL; Enhanced flushing; mass flux; source zone