Abstract:
This article deals with the destruction of cyanide and thiocyanate ions by bacterial and chemical methods.
Adsorption with granulated activated carbon and oxidation with sodium pyrosulfite in the presence of a copper
sulfate catalyst were used as methods of chemical destruction. The bacterial method of destruction was
carried out using the bacterial consortium Agrobacterium tumefaciens AC-1, Agrobacterium tumefaciens
AC-2 and Pseudomonas sp. AC-3. The control solutions were placed under identical conditions without the
addition of any reagent. Sodium pyrosulfite was effective reagent at removing cyanide ions with 97 % efficiency
in 1–1.5 hours, while the bacterial consortiumwas the most productive against thiocyanate ions, resulting
99 % removal at 120 hours. Thus, the significant amount of cyanide ions has been removed chemically in
the first stage, to reduce the effect of high cyanide concentrations on the bacterial process. In the second
stage, the cyanide ions have been removed until the MPC levels. In addition, thiocyanate ions were neutralized
completely. Model experiments with technological solutions from the gold mining plant were carried
out. According to the results of the studies, the respective degrees of bacterial destruction of CN- and SCNare
99 % and 99.9 %. The residual concentration of CN- and SCN-ions in the treated solution was ≤0.1 mg/l
and ≤ 4 mg/l, respectively. These amounts correspond to the maximum permissible concentrations approved
in the Republic of Kazakhstan and CIS countries.
