Electro kinetic remediation of contaminated habitats

Abstract

Electrokinetics (EK) is a process that separates and extracts heavy metals, radionuclides and organic contaminants from saturated or unsaturated soils, sludge, and sediments. A low intensity direct current is applied across electrode pairs that have been implanted in the ground on each side of the contaminated soil mass. The electrical current causes electroosmosis and ion migration (electromigration) and electrophoresis, which move the aqueous phase contaminants in the subsurface from one electrode to the other. Contaminants in the aqueous phase or contaminants desorbed from the soil surface are transported towards respective electrodes depending on their charge. The results of several laboratory studies have demonstrated excellent contaminant removal efficiencies by the use of the electrokinetic process (Pamukcu and Wittle, 1992; Probstein and Hicks, 1993). However, recent field applications of the electrokinetic technology have also shown anomalous results (Guzman et al., 2000; Lageman, 1993), which have been attributed mainly to the interaction of the contaminants with naturally occurring electrolytes, humic substances and mixed wastes which are present in the subsurface (Lageman, 1993; Acer et al., 1994). In order to use electrokinetic remediation in the field successfully, the different geochemical interactions that occur in the field soils under induced electricity must first be accurately determined. In addition, mechanisms and their effects can be altered in order to enhance the removal efficiency of lock in non-critical contaminants in the soil by immobilization. Numerous field studies have proven the commercial viability and technical effectiveness of the electrokinetic remediation. However, there is still a lot of scope and avenues to cover in this newly developed technology which are subject to further research.

Key words: Electorkinectics, electromigration, electrolysis, electroosmosis.