In situ sparging: Managing subsurface transport and mass transfer

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:215531

Clayton, W S; Nelson, C H

Mass transfer during in situ sparging (ISS) is generally diffusion-limited, since not all of the contaminated media is directly contacted by the sparged gas. The distance over which diffusion must occur (diffusion path length) and the air-water interfacial area are directly related to the geometry of air-filled pores and the air saturation developed. During ISS, the pore-scale distribution of air fingers is a primary factor controlling these properties. Furthermore, the physical and chemical properties of the sparged gas, the contaminants, and the subsurface strongly influence mass transfer. Numerical modeling of nonsteady-state mass transfer during ISS indicates that the rate of mass transfer is increased for higher air saturations and smaller soil pore sizes. Organic carbon in soils can result in extreme disequilibrium between soil and groundwater. This may account for the observed ``rebound`` of dissolved contaminant concentrations after shutdown of sparging systems. Ozone is a strong oxidizer which has been applied to groundwater via ozone sparging. Numerical modeling and site data for ozone sparging show that the process is sensitive to the ozone reaction rates and the air flow dynamics. Transfer of ozone to groundwater can be maximized by increased ozone injection concentrations and increased air saturations.

• OSTI ID: 215531
• Report Number(s): CONF-951139--
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AIR-WATER INTERACTIONS
BIODEGRADATION
DATA
ENVIRONMENTAL TRANSPORT
GROUND WATER
IN-SITU PROCESSING
INJECTION WELLS
MATHEMATICAL MODELS
ORGANIC COMPOUNDS
REMEDIAL ACTION
SOILS
TECHNOLOGY ASSESSMENT