Irizarry-Montalvo, MarĂa de L.
Loading...
1 results
Publication Search Results
Now showing 1 - 1 of 1
Publication Enhancement of TCE volatilization and vapor extraction from variably-saturated clay using salt and alcohol solutions(2015) Irizarry-Montalvo, MarĂa de L.; Padilla-Cestero, Ingrid Y.; College of Engineering; Hwang, Sangchul; Harmsen, Eric; Department of Civil Engineering; PĂ©rez AlegrĂa, Luis R.One of the most common dense non-aqueous phase liquids (DNAPLs) found in polluted underground systems in the U.S. is trichloroethylene (TCE). Most of the remediation technologies for chlorinated solvents like TCE have been designed for sands and high permeability media, therefore new technologies need to be developed to successfully remove these contaminants from tight formations. Previous research has demonstrated enhanced remediation of TCE-contaminated sites through the use of combined treatment technologies using surfactant- and gravity-induced mobilization, dense brine containment and collection, and vapor phase extraction in saturated heterogeneous soils. This research evaluates and develops the enhancement of TCE volatilization and vapor extraction from variably-saturated clay by the addition of salt and alcohol solutions. Enhanced volatilization of TCE is assessed in static and dynamic reactors. The effect of salt content on permeability is assessed through soil-air permeability measurements at different water contents and salt concentrations. Air permeability measurements indicate that the air permeability of Coto clay could be enhanced by the addition of NaCl at low moisture contents. Results for static batch experiments indicate that NaCl enhances vapor TCE extraction for reactors containing TCE-solution with TCE NAPL, for NaCl concentrations below 4.28 M. In the absence of TCE NAPL, for low TCE aqueous concentrations, a high NaCl concentration (4.28 M) yields higher TCE vapor concentrations, and suggests potential enhancement in vapor TCE extraction. Results for the dynamic flux experiments indicate that in TCE-solution with TCE NAPL, a NaCl concentration of 0.60 M yields higher TCE vapor concentrations than in absence of NaCl. NaCl also has a significant effect on TCE solution with saturated clay (i.e. Coto clay) in presence of MeOH. Results also indicate that in unsaturated clay (i.e. Coto clay) NaCl has a significant effect on TCE volatilization. MeOH has a significant effect on TCE solution with or without TCE NAPL. In general, results show that there is a potential for enhanced vapor-phase extraction of TCE by using salt and methanol solution. The differences are, however slight for NaCl. Other salt solutions may show greater enhancement. A test bed was designed to be tested as part of another project to determine if a cycled injection of brine and alcohol solutions enhances soil vapor extraction of TCE from clayey soils. The design integrated a soil column, liquid injection and vapor extraction points, vapor samplers, vacuum, and flow meters. The suggested experimental design involves the cycled application of an alcohol aqueous solution (10%), followed by a brine solution, both injected through reactant delivery membranes, and vapor extraction through extraction wells. Air pressures, flow rates, solution delivery rates, and changes in water content at the bottom boundary are to be monitored during the SVE enhancement experiments.