Cyanide has been widely used as an essential raw material in several industries including textile, plastics, paints, photography, electroplating, agriculture, food, medicine and mining/metallurgy. Because of its high affinity for gold and silver, cyanide is able to selectively leach these metals from ores. Cyanide and cyanide compounds in wastewater streams are regulated. Residues and wastewater streams containing cyanide compounds have to be treated to reduce the concentration of total cyanide and free cyanide below the regulated limits.