Biodetoxification of silver-cyanide from electroplating industry wastewater

A bacterial consortium capable of utilizing metal-cyanides as a source of nitrogen was used to develop a microbiological process for the detoxification of silver-cyanide from electroplating wastewater. When the treatment was carried out in a 27-l rotating biological contactor (R3C) in continuous mode, the system could achieve > 99.5% removal of 0.1 mmol l(-1) silver-cyanide (approximately 5 mg l(-1) cyanide and 10 mg l(-1) silver) in 10 h with sugarcane molasses (0.1 ml l(-1)) as carbon source. The silver ions set free during biodegradation were efficiently adsorbed by the bacterial biomass. The RBC-treated effluent was found to be safe for discharge into the environment, as confirmed by chemical analysis and fish bioassay studies.