Basic principles and problems in decontamination of natural disperse systems. The electrokinetic treatment of soils

The main chemical, biological and physical methods of deactivation of such natural disperse systems as soils and bottom sediments from charged and uncharged pollutants are analyzed. The impact of properties of natural disperse systems and the substances causing their contamination on the expediency of using some specific detoxication method is considered. The peculiarities of ex-situ and in-situ treatment are indicated. It is shown that in many cases the use of such well-known methods as washing, flushing, solidification/stabilization, thermal processing, steam extraction, and others is effective and rational. Advantages and disadvantages of considered methods are presented. Much attention is devoted to the fine disperse systems with low aerodynamic and hydrodynamic permeations, which are most complicated from the viewpoint of decontamination and best suited for the use of the electrokinetic decontamination method. Electrokinetic treatment demonstrates an optimal compromise between the degree of decontamination and energy consumption in comparison with other methods, for example, thermal processing. The performance efficiency by using this method is studied depending on such characteristics of dispersions subjected to decontamination as the initial soil pH value, its exchange capacity and buffer capacity. It has been shown that one of the ecologically acceptable ways to accelerate and enhance electrokinetic remediation is the electrohydrodynamic pH control by selecting the pumping rate of neutral electrolytes in electrode chambers. Examples of applying this method for remediation of different types of soil from heavy metals and hydrophobic organic compounds are presented. [Display omitted] •Dispersion decontamination depends on its structure, buffer and exchange capacities.•Heavy metals and radionuclides can be removed at low pH when they are in ionic form.•Removal of noncharged molecules can be achieved by electroosmosis through dispersion.•For mobility in liquid flow hydrophobic organic compounds require solubilizing agent.•Optimal pH in the dispersion medium can be ensured by electrohydrodynamic regulation.