In situ contaminated soil remediation and contaminated soil containment using electrokinetic techniques

Metal contamination is a common problem at hazardous waste sites. There are several techniques that can be applied for the remediation of metal contaminated soils and groundwaters. When we take into consideration low permeability soils and in situ treatments the number of applicable technologies is more and more reduced. One emerging technology promises successful results in these scenarios: the electrokinetic remediation. Electrokinetic remediation relies on the application of low intensity direct current between electrodes places in the soil. Contaminants are mobilized in the form of charged species, particles or ions, transported to the electrodes and subsequently treated above ground. Electrokinetic also can be used to slow or to prevent migration of contaminants. This practice has been named "electrokinetic fencing". The range of potential contaminants that could be removed or captured is broad: heavy metals, nonmetalic toxic elements, radionucleides, some organic compounds (chlorinated volatile compounds, solvents, BTEX, phenols,...), etc. The technology can be used with several types of soils: sands, silts, fine-grained clays and sediments. This paper presents the description, results and conclusion of laboratory experiments developed to optimise the design of a remediation/containment electrokinetic system and the design of pilot scale experiences. These studies are in development in the framework of several projects involving Technological Centres and private companies. One of these projects is being partially financed by the Bask Government through the INTEK programme. This project, called CONTISOIL, is developed by the compaines Geyser-HPC, Hidronor, Idom, Ingemisa, Inguru consulting, Limia & Martin and Recisuelos. LABEIN supports technologically the electrokinetic laboratory/pilot scale components of the project. This paper describes the at the moment advance in these aspects.