“…The process is one of the more common physical separation and leaching methods for treating granular solid wastes and contaminated soils and sediments. Washing is also used to remove arsenic and other contaminants from ore deposits prior to smelting and from coal before combustion (Mihajlovic et al, 2007;Chapter 5). Chemicals that can promote the leaching or extraction of arsenic from solid materials include oxidants, EDTA (ethylenediaminetetracetic acid; Lee et al, 2004;Englehardt et al, 2007), supercritical carbon dioxide (Wang and Guan, 2005), solutions containing citric acid (C 6 H 8 O 7 ) and KH 2 PO 4 , or a series of washes with HCl and NaOH (Jang, Hwang and Choi, 2007b).…”