COD DECREASING METHOD FROM WASTE WATER

摘要

The method of reducing COD in waste water with urea is employed in the process of acid rinsing of stainless steel and treating nitrogen oxides. The method comprises: (A) treating waste acid and toxic nitrogen oxides produced in acid rinsing with NaOH or NaOH and KMnO4; (B) adding sulfuric acid and controlling pH below 3.0; (C) adding urea ((NH2)2CO); (D) stirring under aeration; and (E) adding alkali such as slaked lime (Ca(OH)2) and controlling pH at 5.8-8.6.