In situ remediation of soils polluted with heavy metals. Part II. Using of electrokinetic treatment

Electrokinetic treatment is used for separation and concentration of heavy metals, radioactive elements, organic compounds, from polluted soils, sediments and sludge. A literature review concerning its principal aspects, is presented. When an electric field is applied between electrodes placed in soil, ions movement takes place due to electromigration, electroosmosis and electrophoresis processes. As a result of water electrolysis, two pH fronts are produced, alkaline – at cathode and acid – at anode. Both fronts are moving towards electrodes with opposite charge, and when they meet each other, there is an pH jump which is placed near cathode zone. Time for electrokinetic remediation depends on transport rate, distance between electrodes, and their configuration. For separation of zinc and manganese from a soil sample placed in a hydraulic flux of about 1 cm3/min, and 100, 150, 200 V, maximum yield for manganese and zinc extraction was 72 %, at 200 V. By using acetic acid and EDTA for pH control in electrodes chambers, the removal of nickel was 73% and of cadmium 94%.