| 摘要 |
PROBLEM TO BE SOLVED: To provide a waste liquid treatment method capable of more sharply reducing the concentration of a substance, which has possibility exerting an adverse effect on the peripheral environment in wastewater discharged at the time of reducing treatment of hexavalent chromium, than before without using an ion exchange resin and friendly to environment, and a waste liquid treatment apparatus. SOLUTION: In a pH (acidity) adjusting process A2, formic acid is added (A8) to a waste liquid A1 having hexavalent chromium dissolved therein to adjust the pH of the waste liquid to acidity and, in a reducing process A3, hydrogen peroxide is added (A9) to the pH-adjusted waste liquid to reduce hexavalent chromium to trivalent chromium. Next, in a process A4 for decomposing hydrogen peroxide in the wastewater, catalase is added to the wastewater (A10) to decompose hydrogen peroxide and, in a pH (alkalinity) adjusting process (A5), an alkali agent is added to the waste liquid (A11) to form chromium hydroxide and, in a flocculation, sedimentation and separation process A6, the waste liquid is separated into a sediment (chromium hydroxide) A7 and a supernatant liquid B1. COPYRIGHT: (C)2006,JPO&NCIPI
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