Vacuum-enhanced pump and treat systems are a combination of two different remediation technologies with a goal of improved performance. Basic pump and treat systems utilize submersible pumps to remove contaminated groundwater,and a variety of treatment technologies on the surface to remediate the groundwater before discharge. Soil vapor extraction systems apply negative pressure (vacuum) to the unsaturated soil facilitating the removal of contaminated vapors. By applying soil vapor extraction techniques to a basic pump and treat system, groundwater recovery rates can be dramatically improved, depending on site conditions.
As with a basic pump and treat system, the submersible pumps in a vacuum-enhanced system can either be electrically or pneumatically powered. The groundwater discharge lines from the various wells are normally combined at the treatment system using a manifold. The groundwater treatment technologies employed are dependent on the contaminants and required discharge quality. A typical treatment chain for petroleum contamination might consist of an oil/water separator, an air stripper, and activated-carbon vessels.
Negative pressure is created in the extraction wells by a vacuum blower installed in the treatment system. This negative pressure not only induces flow of contaminated air to the treatment system, but also increases the flow of groundwater to the submersible pumps. Contaminated vapors from the extraction wells are combined into one stream, usually at the treatment system, using a manifold. A vapor/liquid separator then separates the majority of the entrained liquid which is treated with the extracted groundwater, while the vapor stream is extracted by the vacuum blower. The effluent vapor is either discharged or treated, using activated carbon or an oxidizer, and then discharged.
Considerations in the design of a vacuum-enhanced pump and treat system include: the number of extraction wells, required air and water flow rates, required vacuum, levels of contaminants, and discharge requirements. Depending on the site conditions and contaminants, a number of vacuum pumps, submersible pumps, and vapor and liquid treatment technologies are available.
Please follow the links to view the various types of equipment used in vacuum-enhanced pump and treat systems.
