Cyanidation is widely used by several gold mining companies worldwide. Since its wastewaters contain cyanide, appropriate treatments must be applied to remove this pollutant. Combinations of ozone (O3), hydrogen peroxide (H2O2) and activated carbon (AC) can be used for this purpose. In this work, synthetic cyanide solutions ([CN¯]o = 15.37 mM) were treated using O3 and the combinations O3/H2O2, O3/AC and O3/H2O2/AC under alkaline conditions. O3 was produced from dry oxygen at a rate of 2.51 g O3/h ([O3] gas-phase = 6.9x10-2 g/L). The concentration of cyanide (CN¯) and O3 consumption were measured and the performance of the treatments evaluated. The highest cyanide removal was reached at pH 11.0 for all cases and with 10 mg H2O2/ mg O3 upon adding H2O2. In contrast, the addition of AC did not improve the cyanide removal in comparison with O3 alone. The best cyanide removal was achieved with the combination O3/H2O2 followed by the combination O3/H2O2/AC. Moreover, cyanidation effluents were treated using the combination O3/H2O2. In this case, almost a total removal of free cyanide was achieved after 3 min of treatment. Palabras clave: ozonificación, peróxido de hidrógeno, sistema peroxona, carbón activado, cianuración RESUMEN El proceso de cianuración es ampliamente utilizado en la industria minera alrededor del mundo. Las aguas residuales de este proceso contienen cianuro, lo cual obliga al uso de tratamientos apropiados para su remoción. Para ello, se pueden utilizar combinaciones de ozono (O3), peróxido de hidrógeno (H2O2) y carbón activado (CA). En este trabajo se trataron, soluciones sintéticas de cianuro ([CN¯]o = 15.37 mM) con el uso de O3 y las combinaciones O3/H2O2, O3/CA y O3/H2O2/CA en condiciones alcalinas. Se produjo O3 a partir de oxígeno seco con una producción de 2.51 g O3/h ([O3] fase gaseosa = 6.9x10-2 g/L). Se evaluó el comportamiento de cada proceso y se midió la concentración de cianuro (CN¯) y el consumo de ozono durante los tratamientos. La mayor remoción de cianuro se alcanzó a pH 11.0 para todos los casos. Al añadir H2O2 la remoción fue mayor al usar 10 mg H2O2/mg O3. Por otra parte, la adición de CA no
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