To provide a treating method of cyanide-containing waste water containing ammonia nitrogen by which only cyanides can be removed without changing ammonia nitrogen into nitrate nitrogen when waste water containing cyanides and ammonia nitrogen is treated by using ozone or by using a method of combining ozone with ultra-violet light.
In the treating method for removing the cyanides from the waste water by oxidation using ozone or using ozone with ultra-violet light in combination, an end point of oxidative removing reaction of the cyanides is judged by oxidation-reduction potential and only the cyanides are removed without changing ammonia-form nitrogen into nitrate-form nitrogen. At that time, pH of waste water is adjusted into a range of 7 to 10 and further preferably fluctuation of pH during oxidative removing reaction of the cyanides is controlled within ±0.5.
WAKABAYASHI MASAO
USHIO RYOZO
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