Depollution of oil-contaminated soils by electro-injection

The paper presents the results of an experimental research on the use of electric fields to decontaminate permeable soils polluted by hydrocarbon wastes. Several models of soils (permeability = 10(-8) to 10(-6) m/s; porosity = 15 to 40%) were tested in the laboratory, ranging from sands to clayey consolidated soils, as well as oils of different polarities and acidities. The method used consists in simultaneously or alternately injecting water and electric current in the medium and measuring the oil recovery as a function of time. The interpretation of the results focuses on electrochemical and electrokinetic phenomena. The conclusion of this research is that electro-injection can be an efficient depollution method in the case of oil-contaminated permeable soils, but its use requires the knowledge and/or control of many parameters, including the intensity of the electric field and the conditions of its application, the pH and normality of the pore water, the type of oil, the clay content of the soil, etc.