Laboratory examination of soil venting for the recovery of volatile organic contaminants from unsaturated soil /
| Main Author: | |
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1989.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | Soil venting offers promise as a method for recovering volatile contaminants from unsaturated soil. This technique involves the withdrawal of air from a field of dry wells to recover pollutant vapors. Field-scale venting applications have successfully recovered large quantities of volatile organics from contaminated soil. However, attempts to document recovery rates and final concentrations in pilot studies have met with limited success, and previous laboratory studies have been restricted to artificial or modified soil. Aromatic hydrocarbons were removed from these artificially-contaminated soils through abiotic volatilization induced by airflow. Recovery rates and total mass removed were confirmed with a closed mass balance at the end of each trial. Undisturbed, natural soils were studied to indicate the behavior expected from inhomogeneous, anisotropic, structured media in the field. These studies were carried out on fine sand and silt loam. Responses of recovery rates to moisture content, airflow rates, and initial dosages were recorded. An initial period of quasi-equilibrium vapor yield was found to correspond with residual solvent concentrations greater than 5000 or 8000μg g^-1 on Weswood fine sand and Weswood silt loam, respectively. This period of recovery is called phase I, and is followed by a transition to a period of low vapor yield, called phase II. The phase II loss rates were found to be considerably lower than predicted by an equilibrium-based model devised by Roy and Griffin (1989). An empirical model which relates loss rate to residual concentration is presented. This model can be applied to soils similar in structure and texture to those investigated in this study. Furthermore, this procedure can be applied to a wide range of soils and pollutants by generating two coefficients with a similar, short-term air stripping study. This method appears to be a more expedient procedure than to develop the data required to utilize mechanistic models currently available. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Soil science." |
| Physical Description: | x, 162 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |