TREATMENT OF CHROMIUM-CONTAINING WASTE WATER

PROBLEM TO BE SOLVED: To easily treat a chromium ion even in a chromium-contg. waste water difficult to remove by an ordinary neutralizing settling method such as chromium-contg. waste water from a tanning plant contg. oil and fat, org. matter, surfactant, sodium chloride, etc., in the treatment of the chromium-contg. waste water contg. a chromium ion and at least one kind inhibitor selected from a group consisting of a neutralizing settling inhibitor, an adsorption inhibitor and an ion exchange inhibitor. SOLUTION: In this treatment of the waste water contg. the chromium ion, a reaction product formed by heating and reacting in an alkali aq. soln. by using a fly ash as a starting material, that is, fly ash zeolite and an iron salt are added to a waste water contg. oil and fat, org. matter, surfactant, the common salt, etc. together with the chromium ion and stirred to remove the chromium and the inhibitor, and the treating agent of the waste water contg. the chromium ion, and the oil and fat, the org. matter, the surfactant, the common salt, etc., consisting of 100-500pts. reaction product formed by heating and reacting in the alkali aq. soln. by using the fly ash as the starting material and having >=pH12 is used.