Electrokinetics removing permeability soils

Since the mid-1980s, electrokinetics (EK) has been widely used as a soil remediation method, especially for low-permeability soils. Numerous studies have demonstrated the effectiveness of EK in the removal of soil contaminants. At first, most investigations focused on metals and only a few targeted relatively soluble organic pollutants, such as gasoline hydrocarbons, phenols, and trichloroethylene. In the case of hydro-phobic organic compounds (HOCs) with low solubility in water, but with a high tendency to be adsorbed onto soil, electrokinetic remediation was previously considered as not applicable because transport by electroosmosis and/or electrophoresis was not to be expected (Acar et aL, 1995 Virkutyte, SiUanpaa, and Latostenmaa, 2002). Therefore, methods to increase the solubility of HOCs had to be coupled with electrokinetic remediation. 

Yuan C, Chiang TS. (2007). The mechanisms of arsenic removal from soil by electrokinetic process coupled with iron permeable reaction barrier. Chemosphere 67 1533-1542. 

Electrokinetic treatment is based on passing a direct current flow through a contaminated soil. The resulting processes (electrolysis, electroosmosis, electrophoresis, and electromigration) remove toxic components from the soil. Although this method has been known for quite some time, its application in soil remediation began only in the second half of the twentieth century. It has recently come to the attention of environmental professionals because of its potential to remove pollutants from low-permeability soils, since processes that govern electrokinetic contaminant transport are not as easily hindered by low hydraulic conductivity. 

Murillo-Rivera B, Labastida I, Barron J, Oropeza-Guzman MT, Gonzalez I, Teutli-Leon MMM (2009) Influence of anolyte and catholyte composition on TPHs removal from low permeability soil by electrokinetic reclamation. Electrochim Acta 54 2119-2124... 

The applicability of solvent flushing, however, is often limited by the characteristics of the soil, especially the particle size distribution. While sandy soils may result in xmcon-trolled fluid migration, clayey soils with partieles size less than 60 pm are often considered unsuitable for in-situ solvent flushing due to low soil permeability. In an attempt to remove PAHs from poorly permeable soils, Li, et alP investigated the possibility of combining cosolvent flushing with the electrokinetie technique. Electrokinetic remediation... 

Electrokinetic treatment can be used to remediate soils, sludges, and sediments contaminated with heavy metals and organic hydrocarbons. Electrokinetic treatment works well on clay-type soils with low hydraulic permeability, which are difficult to treat using other in sitn technologies. Electrokinetic permeabilities for aqueous systems in clays have been demonstrated to be up to 1000 times greater than normal hydraulic permeabilities, and some heavy metals have exhibited removal efficiencies of up to 100%. 

Lynntech, Inc. s (Lynntech s), electrokinetic remediation of contaminated soil technology is an in situ soil decontamination method that uses an electric current to transport soil contaminants. According to Lynntech, this technology uses both direct current (DC) and alternating current (AC) electrokinetic techniques (dielectrophoresis) to decontaminate soil containing heavy metals and organic contaminants. A non homogeneous electric field is applied between electrodes positioned in the soil. The field induces electrokinetic processes that cause the controlled, horizontal, and/or vertical removal of contaminants from soils of variable hydraulic permeabilities and moisture contents. 

In situ electrokinetic extraction (ISEE) is an in situ extraction technology that uses specialized lysimeter electrodes to remove anionic contamination from unsaturated soil. This technology is primarily used on soils with low permeabilities. During ISEE, a direct electric current is... 

The removal of chlorinated compounds from soils has long been a challenging task. Conventional remediation technologies such as pump-and-treat and natural attenuation have failed to clean up most contaminated sites to desired levels. Therefore, innovative technologies such as electrokinetic remediation have been developed the latter has been considered for the removal of contaminants from the soils with low hydraulic permeability. 

Considering the effectiveness of the simultaneous heavy metals and PAH removal, it can be concluded that SEKRIOP might be used for an electrokinetic in situ remediation of mixed contaminated soils. The development of the above-described multifunctional method permits remediating the soils, particularly those characterized with low permeability. The results from the research can be applied to various municipal and industrial sites containing petroleum products and heavy metals. 

Chung HI, Lee MH. (2007a). Electrokinetic permeable reactive barrier for the removal of heavy metal and organic substance in contaminated soil and groundwater. 6th Symposium on Electrokinetic Remediation (EREM 2007) (ed. C CameseUe), June 12-15, Vigo, Spain University of Vigo, pp. 17-18. 

Despite the relatively good results found in literature for soil contaminated with TCE, the removal and elimination of COCs requires enhanced electrokinetic technologies. They comprise the use of solubilizing agents such as cosolvents, surfactants, or cyclodextrins. The other possible alternative for the removal of COCs from soil implies the combination of electrokinetic with other remediation techniques such as chemical and electrochemical oxidation/reduction, permeable reactive barriers, electrolytic barriers, and electric heating. 

Similarly, there are other chemical compounds used to remove organic compounds [17] electrokinetically enhanced persulfate oxidation of PCBs in low-permeability clayey soils, yielding 77.9 % degradation of PCBs with thermal activation after 7 days remediation of 1,2-dichloroethane contaminated soils using electro-kinetic-assisted nano FesOVSaOg processes, with a removal efficiency of more than 96 % after 14 days and degradation of sorbed hexachlorobenzene using an electrokinetic Fenton process. 

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