The treatment of contaminated soil could be in many cases the best solution to obtain secondary raw materials and to save money avoiding dump disposal. This article deals with the Soil Washing technology. The aim is to make the reader aware of what this kind of plants can do in the soil remediation field. In a Soil Washing plant the contaminated materials passes through different treatment units carried on by water. The final purpose is to separate pollutants from the natural matrix using chemicals and/or physical processes and to concentrate the contaminated fraction. In this way there are two main outputs from the plants: a major part of “cleaned” soil that could be recovered as a secondary raw material, and a minor part of dried sludge that contain pollutants. A good comprehension of the pollution is required to build an efficient Soil Washing plants. In fact the most suitable treatment units have to be chosen and put in the right sequence to get the purpose of removing contaminants until their concentrations are under the legal thresholds. Even if a great amount of water is requested, almost all of it could be recycled and reused in the same plant. The possibility of building a washing plant on site is another positive aspect of this remediation technology and allows to avoid the transportation of soil and the pollution caused by vehicles. The costs of this technology are covered by the saving of disposal costs and by the recovery of secondary raw materials obtained with the remediation processes. This technology could be applied also to some kind of waste.
