Washing and Electrochemical Methods

All remediation methods which remove, convert, or destroy contaminants in a matrix, i.e., soil or groundwater, except thermal and biological methods, are defined as chemical-physical methods. It is possible to pursue a variety of strategies with chemical-physical methods (Offutt etal. 1988)  

Typical examples of separation methods include washing and extraction processes used for relatively highly concentrated liq- 

The mechanical and physical pretreatment processes include screening and size-reduction, density and particle separation in settling ponds, as well as hydrocyclone and fluidized bed processes, dewatering by 

The properties of water as a washing agent and a solvent can be enhanced with additives. Several types of additives include (i) surfactants that improve the wettability of the soil components and improve the solubility of lipophilic impurities (ii) complex-ing agents which convert heavy metals and their insoluble compounds into water-soluble compounds (iii) flotation agents (collectors and foamers), which convert certain insoluble substances into a separable phase and (iv) acids or bases for pH control which is necessary for the stability of compounds and for the selectivity of the flotation processes (Venghaus and Werther 1998 Wilichowski 2001). 

Hydrochloric, sulfuric, and nitric acids are used in soil remediation to extract metals. Because of the good solubility of basic salts (e.g., lead and zinc), it is also possible to use treatment with sodium hydroxide. Cyanides can also be converted with NaOH however, experience has shown that the treatment of iron cyanide in fines is difficult. The treatment of wastewater generated during the treatment of contaminated soil employs the same techniques as those used to treat industrial wastewater. Calcium oxide is most often used for the precipitation of metals as this process also removes sulfates, fluorides, phosphates, and arsenates. Most effective in the elimination of heavy 

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