The significance of geochemistry and microbiology on reducing aquifer permeability during air sparging
- Leggette, Brashears and Graham, Inc., St. Paul, MN (United States)
Air sparging is an in-situ, saturated-zone treatment technology that is commonly considered for the remediation of sites contaminated with volatile organic compounds (VOCs). The technology involves injecting air into a contaminated aquifer at a position beneath the deepest portion of the impacted area. As the air passes through an aquifer, it volatilizes VOCs that exist in interstitial spaces as nonaqueous-phase liquid (NAPL), have been dissolved in ground water and have adsorbed to saturated soil. The contaminants are transferred to the vadose zone, via air channels, where vapors are collected by a soil-vapor extraction system for treatment. Air sparging also oxygenates the aquifer, which can enhance the biodegradation of aerobically-degradable contaminants. The injection of air into ground water can have major effects on the geochemistry of an aquifer. Ground-water sample analyses and detailed monitoring of pilot-scale tests yield significant insight into the geochemical changes that occur in an aquifer subjected to air sparging. Anaerobic (reducing) conditions are rapidly changed to aerobic (oxidizing) conditions, as evidenced by changes in redox potential, dissolved iron concentration and groundwater conductivity. The pH and temperature of ground water adjacent to the air sparging well also rises, sometimes as much as two standard pH units and 15 degrees Celsius, respectively.
- OSTI ID:
- 215529
- Report Number(s):
- CONF-951139--
- Country of Publication:
- United States
- Language:
- English
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