ABSTRACT
Electrokinetic remediation is an environmental technology specially designed for the removal or degradation of contaminants in soils, sediments, sludges, and even solid wastes. This technology relies upon the application of a low intensity electric field directly to the porous material to be treated. Under the effect of an electric field, the contaminants are mobilized and transported towards the electrodes anode and cathode. The two main transport mechanisms are electromigration and electroosmosis. Electromigration is the transport of ions in solution in the interstitial fluid towards the electrode of opposite charge. Electroosmosis is the net flux of water induced by the electric field that, under natural conditions, flows from anode to cathode transporting the contaminants in solution out of the solid material. Electrokinetic remediation has shown several successes in the removal of inorganic and organic contaminants from soil. Furthermore, this technology is able to remediate fine grained and low permeability soils where other technologies have failed. In electrokinetics, the removal of contaminants requires their mobilization and solubilization in the interstitial fluid. The solubilization of contaminants can be enhanced with the addition of facilitating agents (acids or bases, complexing agents, surfactants etc.) and the pH adjustment in the solid material. The facilitating agents can be transported into the solid material by electromigration or electroosmosis, and the pH in the solid material can be controlled by the electrochemical split of water combined with the addition of an acid or base. Field applications of electrokinetics on contaminated sites have proved that this technology can be used on a large scale.
