Biodetoxification of Silver-Cyanide from Electroplating Industry Wastewater.

Abstract

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 (RBC) in continuous mode, the system could achieve > 99·5% removal of 0.1 mmol l-1 silver-cyanide (≈ 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.