Vacuum extraction systems

The radius of influence of a vacuum extraction system, if necessary, to recover sparged vapors and... 

Terra Vac has developed Dual Vacuum Extraction (DVE) technology for the extraction of volatile organic compounds (VOCs) from groundwater and sod. DVE combines a soil vacuum extraction system with a groundwater recovery system. DVE wells operate below the water table and allow for extraction of VOC-contaminated groundwater and volatilization of VOCs in the soils above the water table. 

Depending on the depth of the soil being remediated, a vacuum extraction system may be connected to vertical or horizontal extraction wells. As air flows through the soil pore spaces, the contaminants are volatilized in place and driven toward the extraction wells. Contaminants are then recovered and treated at the surface, usually by activated carbon, catalytic oxidation, or thermal treatment. 

Vacuum extraction alone is limited to treating unsaturated soils, and successful remediation is contingent upon factors such as soil properties and the volatility of the contaminants. Ideally, measured soil permeabilities should range between 10 " and 10 cm/sec, and contaminants should have a Henry s constant of 0.001 or higher. Also, sites with complex stratigraphy or contaminant distributions may require pilot demonstrations prior to the full implementation of a vacuum extraction system. 

Terra Vac, vacuum extraction system (Cheremisinoff, 1989) VOCs and TCE Valleys Products Co., Ltd., Montana... 

USEPA, Terra Vac, In-situ vacuum extraction system, Applications Analysis Report, Cincinnati, OH, EPA/540/A5-89/003, 1989. 

Applications Analysis Report Terra Vac In Situ Vacuum Extraction System... 

Technology Evaluation Report, SITE Program Demonstration Test, Terra Vac In-Situ Vacuum Extraction System, Groveland Massachusetts, EPA 540/A5-89/003a. 

The ice bath is removed after addition of the sodium cyanide, and the mixture is stirred for 4 hours. The organic layer is separated, and the aqueous layer is extracted with three 500-ml. portions of ether. The combined ethereal extracts and organic layer are washed with two 100-ml. portions of cold water and dried over anhydrous magnesium sulfate. The ethereal solution is filtered, and the ether is removed at atmospheric pressure. The residue is transferred to a vacuum distillation system and distilled under reduced pressure (Cauiionl See Note 2). The yield of dlmethylaminophenylacetonitrile boiling at 88-90°/l.9-2.1 tnm. is 842 844 g. (87-88%) (Notes 3 and 4). 

In the last several years, on-line extraction systems have become a popular way to deal with the analysis of large numbers of water samples. Vacuum manifolds and computerized SPE stations were all considered to be off-line systems, i.e., the tubes had to be placed in the system rack and the sample eluate collected in a test-tube or other appropriate vessel. Then, the eluted sample had to be collected and the extract concentrated and eventually transferred to an autosampler vial for instrumental analyses. Robotics systems were designed to aid in these steps of sample preparation, but some manual sample manipulation was still required. Operation and programming of the robotic system could be cumbersome and time consuming when changing methods. 

The vacuum extraction process involves using vapor extraction wells alone or in combination with air injection wells. Vacuum blowers are used to create the movement of air through the soil. The air flow strips the VOCs from the soil and carries them to the surface. Figure 18.14 shows the flow diagram for such a process. During extraction, water may also be extracted along with vapor. The mixture should be sent to a liquid-vapor separator. The separation process results in both liquid and vapor residuals that require further treatment. Carbon adsorption is used to treat the vapor and water streams, leaving clean water and air for release, and spent GAC for reuse or disposal. Air emissions from the system are typically controlled by adsorption of the volatiles onto activated carbon, by thermal destruction, or by condensation. 

A further development is the combination of the pin barrel extruder system with that of the Transfermix (see under EXTRUDERS, MIXERS). The combined system is known as Pinconvert and is available with or without vacuum extraction. 

Several points need to be considered when applying this pressure method of sample collection. All of the extraction system parts must be explosion proof and the distance from the ceramic cup to the sample bottle must be as short as possible. The sample collection bottle should be at the same level as the ceramic cup. If it is higher, additional vacuum will need to be applied to move the sample water into the sample bottle. Sample storage, once the water is collected, is determined by the analyte of interest. 

All filtering and extraction systems must be checked for compatibility with the analyte of interest. Some or all of the analytes may be absorbed or otherwise lost during the extraction process, and this must be known beforehand. Carbon may be lost by high vacuum differentials between sampler and soil water. Long extraction times may lead to distortions in the results of the sample analysis [5],... 

T0655 Remediation Service International, Spray Aeration Vacuum Extraction (SAVE) System... 

T0689 SBP Technologies, Inc., Membrane Filtration T0691 SBP Technologies, Inc., Solid-Phase Bioremediation T0706 Separation and Recovery Systems, Inc., SAREX Process T0712 SIVE Services, Steam Injection and Vacuum Extraction (SIVE)... 

T0439 IT Corporation, Fluid Injection with Vacuum Extraction T0441 IT Corporation, Hybrid Thermal Treatment System (HTTS)... 

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