ABSTRACT
While low-temperature and thermal oxidation technologies are employed most commonly for destruction of cyanide species in water, soils, sludges, and solids (see Chapters 20 and 22), physicalchemical separation of cyanide species is an alternative, sometimes less expensive, treatment approach for cyanide-bearing waters. This is especially the case for treatment of strong metalcyanide species, which often are not as readily oxidized as free cyanide and weak-acid-dissociable (WAD) cyanide. The reactivity of cyanide species on certain kinds of solid surfaces, activated carbon in particular, is exploited for adsorptive removal from water. In addition, the ability of cyanide to react with certain metals, especially iron, to form relatively insoluble solids is exploited for precipitative removal of free and metal complexed cyanide. Finally, air stripping can be used to remove free cyanide from water, as HCN is a volatile species. In this chapter, we examine adsorption, precipitation, and air stripping treatment approaches that have been used to treat various cyanide-bearing waters.
