Performance of various cyanide degrading bacteria on the biodegradation of free cyanide in water.

• Cyanide degrading bacteria (CDB) from various sources were chosen. • CDB ability to degrade FCN in liquid medium was tested and its performance was compared. • Deposit materials in decontaminated liquid medium were characterised. • Possible reuse of deposit materials was revealed. This study reports on the biodegradation of free cyanide (FCN) by cyanide degrading bacteria (CDB) that were isolated from mining wastewater and thiocyanate containing wastewater. The performance of these isolates was compared to cryopreserved CDBs that were used in previous studies. The performance of the isolates to degrade FCN was studied in batch cultures. It was observed that the CDB from the thiocyanate wastewater showed higher biodegradation rates (2.114 g CN−. L−1.O.D 600 nm −1.h−1) compared to the isolates from the mining wastewater. The isolates from the cryopreserved CDBs and from the mining wastewater achieved a biodegradation rate of 1.285 g CN− L−1.O.D 600 nm −1.h−1 and 1.209 g CN−.L−1.O.D 600 nm −1.h−1, respectively. This study demonstrated that the source of the organisms plays a significant role on FCN biodegradation. [ABSTRACT FROM AUTHOR]