Abstract: A method for effectively treating waste water discharged from the ammoxidation process for the production of acrylonitrile which comprises treating waste water or a preliminary oxidized liquid of said waste water with activated carbon in an adsorption and separation zone, subjecting the spent carbon slurry from said adsorption and separation zone to wet oxidation in the presence of copper values and ammonium ions at a pH of not higher than 5 in a regeneration zone to thereby regererate the spent carbon, and recycling the regenerated activated carbon to said adsorption and separation zone. The rate of regeneration of the spent carbon in the regeneration zone can be further increased by adjusting the amount of copper values to at least 1,000 ppm. Thus, the waste water containing extremely hardly decomposable substances can be effectively treated and, at the same time, the spent carbon can be regenerated with less degradation of adsorption capacity.

Abstract: In wet-oxidizing organic waste water containing cyanogen i.e. inorganic-CN, or a compound capable of forming cyanogen under oxidative conditions, if the wet oxidation is conducted in the presence of copper or a copper compound and a specific ammonium salt, COD and the cyanogen concentration can be reduced at highly improved removal ratios. Copper ions resulting from the copper component made present at the wet oxidation step can be effectively removed by precipitation or ion exchange. Accordingly, this treatment method does not cause secondary pollution at all. In case recovery of the copper ions is performed by ion exchange, good results are obtained when the oxidized liquid from the wet oxidation step is flashed at a temperature higher than 100.degree. C. and the pH of the oxidized liquid is adjusted to 4-7 after the cyanogen decomposition step but before the ion exchange treatment. A weakly acidic ion exchange resin is preferably employed.