Geologija / Geology
 ISSN 1392-110X ISSN 2029-056X (online) |
2007 m. Nr. 1 Decontamination of heavy-metal polluted soil BY
electrokinetic remediation
The electrokinetic method used for remediation of soil contaminated with heavy
metals is a new developing technique for cleaning soil from heavy metals and radionuclides. By feeding an electric current through soil one induces movement of charges, which is generated by migration of ions and colloids in water present in pores and by reductive reactions on the surface of electrodes. The aim of the present investigation was to find out whether the electrokinetic soil cleaning method is suitable for cleanup of polluted soils. The method utilizes electrokinesis to drive contaminant species into and through a bed adjacent to a drive electrode. The bed comprises a moderately electrically conductive adsorbent material which is porous and is infused with water or other solvent capable of conducting electrical current. The efficiency of the method depends not so much on soil permeability as on the electric conductivity of water in pores and the distance of movement. The major task and the key goal were to determine suitability of the electrokinetic method for the treatment of soil contaminated with heavy metals (Cr, Cu, Mn, Ni, Zn and Pb). Also, it was important to determine the maximum level of cleanup, dependence on the voltage, the level of soil pollution for which this remediation method would prove to be effective for cleaning soil down to the permitted pollution limits, the type of soil most suitable for this remediation technique, the materials of the electrodes, etc. The electrokinetic method is most effective when cleaning polluted sand and sandy loam. The highest efficiency and smallest residual concentrations were reached when removing manganese and chromium from soil. A higher cleaning efficiency is reached applying 29 V rather than 24 V voltage. However, results were quite similar, therefore to clean soil from heavy metals the standard 24 V voltage could be applied, but the cleaning process should be prolonged. Keywords: soil, pollution, heavy metals, electrokinetic remediation, cleaning efficiency |
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