Injecting air removes contaminants
In Situ Air Sparging
- Transfer volatile, strippable, compounds from the dissolved phase into the gas phase and transport these to the vadose zone, where they are attenuated naturally or captured by soil vapour extraction. This process is referred to as ‘Air Stripping’.
- Enhancing aerobic natural degradation. Contaminants are not transported but are degraded in situ. This process is referred to as ‘Biosparging’.
- In specific cases, gas injection can be deployed to promote separate phase hydrocarbon recovery.
Contaminant stripping
The injected air is the driving force to transport contaminants to the vadose zone in air stripping. This is only effective for compounds with a suitable Henry’s constant. In some cases, soil vapour extraction is used to capture and remove contaminants from the vadose zone; in other cases, natural attenuation suffices to degrade the contaminants before they migrate to atmosphere.
Aerobic biodegradation
Biosparging focusses on elevating groundwater oxygen concentration to above 2 mg/l, the optimum level for aerobic biodegradation.