| 摘要 |
PROBLEM TO BE SOLVED: To economically decolor colored waste water within a short time without forming sludge by preliminarily treating colored waste water with a reducing agent and subsequently adding peroxide and a metal salt to the waste water. SOLUTION: When colored waste water is subjected to decoloring treatment, at first, an acid or an alkali agent is used to adjust the pH of colored waste water to 2-12, pref., 4-11. In the mixing of the pH adjusting agent and colored waste water, a stirring mixing tank, a static mixer or an in-line mixer is used. Next, a reducing agent is added to the colored waste water adjusted in pH and, subsequently, hydrogen peroxide and a metal salt are added to the colored waste water treated with the reducing agent to decompose a coloring component. At this time, as the reducing agent, dithionite or sulfite is used. As peroxide, hydrogen peroxide is used. In this treatment, pref., a salt of iron, manganese, copper, chromium, cobalt, nickel, aluminum or zinc is added. |
