TREATMENT OF CYANIDE CONTAMINATED WASTEWATERS AND EFFLUENTS

Wastewater and effluents from the cyanide process generally contain variable amounts of sodium cyanide, acid-dissociable metal cyanide complex and thio-cyanate. In general, the largest source of cyanide in wastewaters is from gold extraction and treatment processes. The other source of cyanide effluent is the plating and metal finishing industries. The major concerns with these cyanide processes are the health and environmental problems associated with cyanide. State and Federal guidelines and regulations propose and specify limits on the concentration of cyanide, free and complexed, that may be discharged into streams. These limits are generally at levels that require some type of cyanide removal before discharge of wastewater or effluent. The paper discusses the conventional methods of treatment for cyanide removal from effluents to meet State and Federal regulations. Novel methods for cyanide removal from effluents are proposed. The major objective of each method is the removal of cyanide in various forms to concentrations that meet the stipulated limits.