Electrokinetic remediation success

While electrokinetic treatment of soils looks promising, most of the work performed was bench-scale, under carefully controlled laboratory conditions. For electrokinetic remediation to be a viable alternative for in-situ cleanup of waste sites, a number of factors will have to be investigated. All of the work to date has dealt with uniformly contaminated soil samples. Studies performed on partially saturated soils will yield different results. Further studies on the removal of mixed metal contaminated soils, using different soil types, are needed. The presence of organic compounds in the soil will also influence successful treatment of real contaminated soils. The use of reagents which could increase desorption and/or solubilization (without further contaminating the soil matrix) may also be areas of future investigation. Finally, field tests need to be performed to substantiate studies accomplished on the bench scale. 

Cosolvent-enhanced electrokinetic remediation of chlorinated pesticides has yet to be explored. Few studies have shown enhancements in the transport of polycyclic aromatic hydrocarbons (PAHs) when cosolvents were used (Maturi and Reddy, 2008 Reddy and Saichek, 2003). The potential success of cosolvents depends on their ability to mobilize the HOCs and to increase the EOF. It was shown that 10% n-butylamine generated the greatest EOF, followed by 20% n-butylamine and water (Maturi and Reddy, 2008). The sorption of solvents to the soil matrix may not be as high as the surfactants, which cause a better solubilization with the same amount of electro-osmotic transport. 

The cost of electrokinetic remediation, like any other remediation technology, is highly site specific. There have been relatively few full-scale installations of electrokinetic processes when compared with conventional remediation processes. There have been more applications of electrokinetics in Europe than in the USA. Since 1987, more than 75 electrokinetic projects have been implemented in Europe (Holland Environment, pers. comm.), while in the USA, very few full-scale appUca-tions have been successfully completed. 

The electrokinetic technology for the remediation of soils, sediments, and groundwater relies on the application of a low-intensity electric field directly to the soil in the polluted site. The effect of the electric field mobilizes ionic species that are removed from the soil and collected at the electrodes. At the same time, the electric field provokes the mobilization of the interstitial fluid in the soil, generating an electroosmotic flow toward the cathode. The electroosmotic flow permit the removal of soluble contaminants. The success of the electrokinetic process rely on the effective extraction and solubilization of the contaminant and on their transportation toward the electrodes, where they can be collected, pumped out, and treated. Many studies have been carried out to determine the influence of the operating conditions and the effect of the soil and contaminant nature in order to improve the applicability and effectiveness of the electrokinetic treatment. 

The effects of electrokinetic treatment have been studied in the presence of other components, such as surfactants like Triton X-114. This has yielded a hydrocarbon removal percentage of about 49 % after 6 h and 66 % after 24 h. This compares with individual chemical and electrokinetic treatments after 6 h of treatment at 1.5 mL min , showing 12 % and 35 % removal, respectively. The coupled system was very successful, although inconvenient in the permanency of Triton X-114 in the soil following remediation [18]. 

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