TREATMENT OF DITHIONIC ACID-CONTAINING WASTE WATER WHEREIN NITRITE ION COEXISTS

摘要

PURPOSE:To remove a dithionic acid from dithionic acid-contg. waste water in which nitrite ions co-exist by adding a sulfamic acid to said waste water to decompose away the nitrite ions and brining such waste water into contact with a weakly basic anion exchange resin which is made into a sulfic acid type. CONSTITUTION:After the dithionic acid-contg. waste water in which the nitrite ions co-exist is adjusted to <=3pH, the sulfamic acid is added to the waste water at such a ratio at which said acid is incorporated therein at 1-1.5 equiv. of the nitrite ions to decompose away the nitrite ions. The waste water is then brought into contact with the weakly basic anion exchange resin which is made into the sulfuric acid type to remove the dithionic acid. As a result, the nitrite ions are efficiently decomposed to harmless gaseous N2 and the COD value of the treated water is decreased. The treated water does not exert an ill effect to a subsequent ion exchange device. The treatment is thus executed without increasing the COD value of the final treated water.