Air-Sparging
Typical Air Sparging System
Air is injected (horizontally and vertically) in channels through the contaminated soil, creating an 'underground stripper' that volatises contaminants for their removal.
- The process applies to contaminated saturated areas (below the water table) and is commonly used to volatilise NAPLs.
- The injected air helps to flush (bubble) the contaminants up into the unsaturated zone to be removed by SVE.
- High air flow rates are used to maintain increased contact between ground water and soil - increasing quantity treated.
- It is typically medium-long term (few years).
Uses:
- Target contaminant groups:VOCs and fuels
- Methane can be added to the sparged air to enhance cometabolism of chlorinated organics.
Limitations:
- May get uneven air flow through the saturated zone - could be uncontrolled movement of polluted vapours.
- Soil heterogeneity may cause uneven treatment.
- Air injection wells designed for site-specific conditions (geology/depth of contaminants)
- Highly variable cost - dependent on the surface area & depth of contamination & no. of wells required.