Soil vapor extraction process

HeatTrodes can function as in situ heat exchangers to achieve effective warming rates for bioremediation and soil vapor extraction processes. 

Soil vapor extraction (SVE) is a relatively new yet widely applied technology for the remediation of soils contaminated with volatile organic compounds (VOC) in the unsaturated zone above the water table (vadose zone). The process consists of generating an airstream through the contaminated soil subsurface in order to enhance the volatilization of organic contaminants and thus remove them from the soil matrix.913... 

Rathfelder, K.M., Lang, J.R. and Abriola, L.M., A numerical model (MISER) for the simulation of coupled physical, chemical and biological processes in soil vapor extraction and bioventing systems, J. Contam. Hydrol., 43, 239-270, 2000. 

The primary focus of this chapter is to introduce approaches that limit (or prevent) migration of hydrocarbon and organic contaminants from the vadose zone into underlying water-bearing zones. The more conventional strategies, including a brief discussion of the process, relative cost, practical constraints, and limitations, are presented. Also presented are two typical soil vapor extraction case histories. 

Ideally, the site characterization study has defined the vertical and horizontal extent of the contamination. Contoured site maps showing the (three-dimensional) distribution of the contaminants allow identification of areas that require extensive restoration, or may be allowed to be monitored to closure under natural attenuation. Knowledge of how much contamination exists and its location is the important first step in the remediation process. Evaluation of these data will permit consideration of the various remediation remedies available. Where the contaminant is contained within the shallow (<6 m) unsaturated zone and is recalcitrant (not readily biodegradable), excavation for off-site treatment or disposal may be the most expeditious procedure. Alternatively, depending on the contaminant, a variety of in situ procedures, including bioremediation, air sparging, soil vapor extraction, and fixation, may be applicable. 

T0406 In Situ Soil Vapor Extraction (SVE)—General T0531 Mirage Systems, Inc., ChemChar Process T0607 Phytoremediation—General... 

T0585 Oxidation Systems, Inc., HYDROX Oxidation Process T0592 Passive Soil Vapor Extraction—General... 

T0564 North East Environmental Products, Inc., ShallowTray Air Stripper T0585 Oxidation Systems, Inc., HYDROX Oxidation Process T0598 Pelorus EnBiotech Corporation, Slurry-Phase Bioremediation T0641 Radian International, L.L.C., Aquadetox/Soil Vapor Extraction (SVE)... 

Dowex Optipore is a polymeric adsorbent used to treat chlorinated volatile organic compound (CVOC) contaminated off-gas streams from remediation processes such as air stripping of groundwater and soil vapor extraction. According to the vendor Dowex Optipore adsorbent has the following advantages over activated carbon ... 

In situ oil skimmers are commercially available for the recovery of free product [i.e., light non-aqueous-phase liquids (LNAPLs) such as oil, grease, or other hydrocarbons] floating on the water table. Oil skimmers can be used alone or in conjunction with other remediation technologies, such as (in situ) soil vapor extraction, bioventing, or bioremediation, or (ex sim) membrane filters, coalescers, or chemical processes. The technology is implemented in sim by lowering the skimmers into wells located in the zone of contamination. 

Potential applications for this technology include the treatment of airstreams contaminated with volatile organic compounds (VOCs) from air stripping, soil vapor extraction, industrial air emissions, and for the cleaning of air in closed environments. PCO is best suited for waste streams with low concentrations of contaminants, and with low to medium flow rates. The AIR-11 process can operate consistently in conditions where flow rates and VOC concentrations are highly variable, even intermittent. 

The process can be integrated with existing technologies, such as thermal desorption, air stripping, or soil vapor extraction. 

This technology is applicable to the treatment of industrial wastewater and contaminated groundwater. The same technology can also be used to effectively destroy airborne contaminants in the off-gases from industrial processes, air strippers, or soil vapor extraction operations. 

The vendor states that the technology has been installed at private industrial sites and military installations for the destruction of VOC off-gases from soil vapor extraction (SVE) systems, air strippers, and process tank vents. The technology is patented and commercially available. The results from demonstrations at three military installations are included in case study overview. The vendor states the following advantages of PDT technology ... 

The Barometrically Enhanced Remediation Technology (BERT ) removes and recovers volatile organic contaminants from soil by enhancing the natural air exchange that occurs in soil as a response to changes in atmospheric pressure. This process is sometimes referred to as barometric pumping or passive soil vapor extraction. The process is a low-cost complement to conventional active-extraction methods because investment and maintenance costs are low and no power is needed. The passive process is better suited than conventional methods for certain problems. 

The Thermatrix, Inc., PADRE process is a commercial, off-gas treatment technology that purifies airstreams contaminated with volatile organic compounds (VOCs). The PADRE vapor treatment process traps VOCs using filter beds that contain a proprietary resin. This regenerative adsorption method involves an on-line treatment bed for infiuent air, while another bed undergoes a desorption cycle. PADRE often works in conjunction with soil vapor extraction or air stripping systems. The PADRE process can be applied at site remediation projects, industrial wastewater facilities, and industrial air processing sites. 

The contaminant absorption and recovery (CAR) technology treats volatile organic compounds (VOCs) in gas streams from such processes as soil vapor extraction, air sparging, and air stripping. The contaminated gas stream passes through an absorption solvent, which is a nonvolatile... 

In situ thermal treatment — In situ thermal treatment allows pollutants to be treated without being excavated and transported. Thermal treatment requires a shorter clean-up time however, high costs are usually associated with the amount of energy and equipment required. For example, enhanced soil vapor extraction is usually an energy-intensive process. 

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