ELECTROKINETIC TREATMENT OF DREDGED SEDIMENTS CONTAMINATED BY HEAVY METALS: THE LIFE+ “SEKRET” PROJECT

Abstract

 The contamination of seabottom sediments, which affects several harbours and water bodies sub­jected to commercial and production activities, is a problem that has emerged in the last decades and is now object of growing attention. In harbours and waterways subjected to dredging activities for granting proper wa­ter depths for navigation, the level of contamination di­rectly affects dredging costs, which grow significantly when the prescribed contamination thresholds are ex­ceeded. Presently, most treatment techniques of metal polluted matrices turn out to be too expensive to be applied to dredging sediments. This is particularly true for silty-clayish sediments, which present low permea­bility and high buffer capacity. In these circumstances, the electrokinetic treatment exhibits its optimal field of application, thus showing optimal potential also for treating sediments from dredging activities. However, despite numerous laboratory tests cited in the litera­ture, full scale applications are still limited, being the treatment of contaminated soils the only consolidated application. The LIFE+ SEKRET project (“Sediment ElectroKinetic REmediation Technology for heavy metal pollution removal”) has, as its main goal, the feasibility demonstration of this technique to treat metal-polluted sediments from seabottom dredging, by building a demonstrative facility in a dedicated area of the Port of Livorno, for treating 150 m3 of sediments. Indeed, in such reality, 100.000 m3 year-1 of sediments are regularly dredged, partly contaminated by Cd, Cr, Cu, Ni, Pb e Zn slightly exceeding the prescribed con­tamination thresholds. The project aims at highlighting the environmental and economic advantages of this so­lution against other treatment techniques or polluted-material landfilling.