TREATMENT OF IRON-CYANIDE COMPLEX CONTAINING CYANIC WASTE WATER

PROBLEM TO BE SOLVED: To treat a cyanide in a waste water to low concn. by irradiating the waste water with UV rays to visible rays after adding an alkali agent and an oxidizing agent to a cyanic waste water containing an iron-cyanide complex, adjusting pH alkaline and oxidizing a free cyanide while separating and removing a precipitate from the waste water. SOLUTION: The cyanic waste water is irradiated with UV rays to visible rays in a reactor 16 provided with a light source 15 after adding the alkali agent to the cyanic waste water containing the iron-cyanide complex from an alkali agent feed device 12 to adjust pH adding the oxidizing agent from an oxidizing agent feed device 13. In this way, a decomposition and oxidation treatment of the iron-cyanide complex is allowed to progress by a two step reaction. That is, at the first step reaction, the iron-cyanide complex is executed by light energy to be decomposed to a free cyanide and iron ion. At the second step reaction, the free cyanide is oxidized with the oxidizing agent supplied from the oxidizing agent feed device 13 to convert it into a carbonate and nitrogen. The waste water with cyanide compd. decomposed and oxidized is discharged from a discharge pipe 17 as a treated water.