TREATMENT OF FERROCYANIC COMPLEX COMPOUND-CONTAINING CYANIC WASTE WATER

PROBLEM TO BE SOLVED: To treat a waste water to make cyanide concn. low in a state that effective availability of light energy used for the decomposition of ferrocyanic complex is kept high. SOLUTION: In a treating method of the cyanic waste water containing the ferrocyanic complex, the cyanic waste water, in which sulfuric acid or sulfuric acid and a soluble sulfate and an oxidizing agent are added, is irradiated with ultraviolet to visible ray to decompose the ferrocyanic complex into iron ion, which is dissociated by the decomposition and fixed with a high solubility iron double salt, and free cyanide. The cyanic waste water containing soluble iron double salt and free cyanide generated by this way is adjusted in pH to be alkaline by adding an alkali agent and after the precipitate such as hydroxide formed by hydrolysis after pH adjusting is separated and removed, the free cyanide is oxidized by adding the oxidizing agent into the free cyanide- containing waste water and irradiating with ultraviolet to visible ray.