Pump-and-treat technology

Pump and treat technology is inherently slow because it depends on ground water for transport of the contaminant to the extraction well. This characteristic is particularly troublesome when the contaminant is only slightly water soluble, adheres to the soil, or collects ia pools within the aquifer. 

Gatliff, E.G., Vegetative remediation processes offers advantages over traditional pump-and-treat technologies, Remediation, 4, 343-352, 1994. 

The following two project descriptions incorporate examples of completed, full-scale applications of pump-and-treat technology to MTBE-contaminated sites. 

TreeMediation is a phytoremediation technology offered by the vendor as an alternative to pump-and-treat technologies and is based on certain tree species abilities to extract large quantities of water from aquifers. TreeMediation uses plant species to assimilate contaminants or to... 

The CESAR (chemically enhanced solubilization for aquifer remediation) technology is a surfactant-enhanced pump-and-treat technology that remediates an aquifer by treating organic contaminants with a chemical surfactant solution. The surfactant solubilizes the contaminants, thus making them more readily transportable to the extraction weUs. This technology is currently commercially available. 

Table 1 shows a cost comparison of UVB, pump-and-treat technology alone, and pump-and-treat technology combined with excavation and bioremediation at a site where the groundwater was contaminated with benzene, toluene, ethylbenzene, and xylene (BTEX) (D122827, p. 1.4). 

The vendor claims that this technology costs 60% less than pump-and-treat technologies (D10308S, p. 2). 

In 1997, it was reported that the vendor was using in situ geochemical fixation to remediate a Midwestern wood treatment site contaminated with chromium. The cleanup is expected to last for 2 years and cost approximately 600,000. The vendor states that treating the site by conventional pump-and-treat technology would have taken more than a decade to complete and would have cost far more (D16925Z, p. 1). 

Table 1 is a comparison of the costs associated with ISRM and pump-and-treat technology. These costs are based on a 1997 study by researchers at the U.S. DOE s Los Alamos National Laboratory. The researchers predicted a 62% cost savings over a 10-year period when using ISRM instead of pump-and-treat to treat chromium-contaminated groundwater (D17151H). 

PerkinElmer, Inc. (formerly EG G, Inc.), reports that NoVOCs installations have treated sites contaminated with benzene, toluene, ethylbenzene, xylene, trichloroethene (TCE), tetra-chloroethene (PCE), and petroleum hydrocarbons. The technology is unlike conventional pump-and-treat technologies in that it avoids the necessity of pumping water above ground for... 

Hydrous pyrolysis/oxidation treatment is relatively simple and can be applied to large volumes of earth. This in situ process is capable of treating both soil and groundwater more quickly than pump-and-treat technologies. HPO has high capital costs but smaller long-term operating and... 

Surtek s surfactant remediation is limited by the same factors that affect any pump-and-treat technology. Performance may be reduced in areas with low hydraulic conductivity or high soil heterogeneity. Incorrect formulation and application of the Surtek method can also make NAPLs more mobile, thereby increasing their potential to migrate to previously uncontaminated areas. In addition, no complete process for the treatment of fiuid extracted by the process has been identified. 

Recovers VOCs from within the cone of depression created by pumping of the aquifer, where pump-and-treat technologies are normally ineffective. 

Above-Ground Bioreactors (Pump-and-Treat Technology). 293... 

This is a handbook on containment of ground water contamination. In situ treatment, and contaminant removal. It discusses subsurface fate and transport processes, ground water and contaminated soils bioremediation, ground water pump-and-treat technologies. soil vapor extraction, and multiphase contamination and free product recovery. 

Narasimhan (1999) suggested that an electrokinetic barrier can work with the pump and treat technology to improve the cleanup in fine-grained soils. By arranging the... 

Low bioavailability of hydrocarbon pollutants can limit the biodegradation by indigenous micro-communities in soils. CDs enhance desorption of the nonpolar contaminants from the solid surface and transfer them to the water-phase biofilms, where the hydrocarbon-degrading microbes work. Therefore, this special character of CDs and their derivatives can be used for enhanced removal of hydrocarbon contaminants from soil [92]. This is so-called CD-enhanced pump and treat technology for the removal of dense, non-aqueous phase liquid from the saturated soil. For example, HP- -CD solution was added into the source zone... 

Containment and/or remediation of contaminated aquifers typically utilizes pump and treat technologies to control contaminant plume migration and ultimately restore the... 

Thus, although pump-and-treat technologies allow, in principle, the effective remediation of NAPL-contaminated aquifers, particularly as far as NAPL lenses are concerned, they appear to be infeasible economically in large-scale remediation operations, and not effective in the removal of entrapped NAPL residual saturation [5,8,11,13]. The latter is strongly held by the capillary forces of the soil/porous matrix, causing the former to become virtually immobile. Its desorption-mobilization from the soil matrix into the aqueous phase requires, therefore, a special attention on designing an effective remediation process. 

Although it provides a decided enhancement over traditional pump and treat technologies, it provides less of an enhancement than does mobilization. On the other hand, in remediation by mobilization within these technologies, the time to remediate the site is independent of the amount of contamination that is, only a few pore volumes will be pumped through the site, whereas no more surfactant is used than in the solubilization method. Overall, there is a much higher enhancement of the solubility of the NAPL in the aqueous phase. On the other hand, remediation of DNAPLs by mobilization may cause the organic phase to move vertically within the aquifer, leading to formation of a pool at the bottom, and the microemulsions formed may require the addition of a cosolvent. 

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