In-situ vapor stripping for removing volatile organic compounds from groundwater

DETAILED DESCRIPTION The present invention is directed to a system for removing VOCs from groundwater.
The system includes means for injecting gas into a well, to force groundwater flow towards the well and to cause VOCs to be transferred from the groundwater to rising gas bubbles inside the well.
The system further includes means for collecting VOC vapor contained within the gas bubbles.
The system may also include a substantially horizontal extraction member in the saturated zone extending toward a zone of contamination for introducing contaminated groundwater into the well.
Additionally, the system may include an infiltration member in the vadose zone for infiltrating groundwater therein and removing VOCs from the well.
The in-situ remediation procedure of the present invention is accomplished by injection of gas into a well, using a combined technique of gas-lift pumping with a form of vapor stripping.
When gas is injected into a well, it causes water to be lifted and forces groundwater flow towards the well, creating a recirculating cleanup zone.
During this process, VOCs are transferred from the contaminated water to the rising gas bubbles inside the well.
The gas containing VOC vapor is collected at the top of the well.
In this system, water need not be lifted to the ground surface.
Rather, the water is forced into the unsaturated zone through a series of drains that are installed beneath the root-zone.
The water then, free of a portion of VOCs, infiltrates back to the water table.
As water continues to circulate, the VOC concentrations are gradually reduced.
The feasibility of the technique of the present invention was analyzed according to concepts of mass transfer of VOCs from water to air-bubbles.
Calculations indicate that the system has promise because equilibrium partitioning between the contaminated liquid and the air bubbles is rapidly established.