REMOVAL OF STABLE METAL-CYANIDE COMPLEXES AND METALLIC IONS FROM WATER EFFLUENT

A process for treating a water effluent, preferably originating from a ore mining process, containing cyanide, metallic ions and stable metal-cyanide complexes having a stability constant K characterized by a logK at 25°C greater than 20, such as one or more cyanide complexes comprising iron, cobalt, nickel, and/or copper, including two main steps: irradiating with UV light in the presence of a peroxygen, preferably comprising H2O2, to form an irradiated effluent, and contacting the irradiated effluent with a solid adsorbent comprising apatite to form a treated effluent. The irradiating step is carried out under alkaline pH with UV light having a wavelength from 200 to 375 nm, preferably UV-C light from 200 to 290 nm, for photo-disassociation of the complexes and forming hydroxyl radicals. The solid adsorbent preferably comprises a synthetic hydroxyapatite, preferably calcium-deficient. The synthetic hydroxyapatite may be a composite made with an additive which preferably contains activated carbon and/or iron.