Low-flow extraction rates prove optimal for soil-vapor extraction
Soil-vapor extraction systems are used to remediate soils contaminated with volatile organic compounds. SVE systems operate by drawing air through the contaminated zone and a dry well to the surface. The air evaporates the VOCs and provides oxygen for in situ biodegradation. Most SVE systems use high flow rates (100 cubic feet per minute) and pumps of several horsepower to achieve VOC removal. However, increasing evidence suggests that lower flow rates (10--20 cfm) can remediate soils efficiently and economically, and may even achieve more rapid cleanup. Moreover, low flow-rate systems require pumps of one-quarter horsepower or less, minimizing initial capital and operating costs, and can be used with low-cost treatment systems for offgases, such as mobile biofilters. Estimates of VOC removal rates from SVE systems usually are based on pump tests conducted when the system is installed. VOC concentrations initially are high, because VOC-contaminated air is drawn from advective zones. After the air in these relatively small zones is displaced several times, a rapid SVE rate draws more air through already clean pores. The removal rate is controlled by the VOC`s rates of diffusion and migration into the soil`s advective zones.
- OSTI ID:
- 93027
- Journal Information:
- Environmental Solutions, Journal Name: Environmental Solutions Journal Issue: 8 Vol. 8; ISSN ESOLE7; ISSN 1077-2537
- Country of Publication:
- United States
- Language:
- English
Similar Records
Field Validation of the NUFT Code for Subsurface Remediation by Soil Vapor Extraction
LNAPL remediation by soil vapor extraction and air sparging