| 摘要 |
<p>PURPOSE:To make waste water disposable by a method wherein waste liquid is filtered after alkali treatment and an inorg. coagulating agent containing Al ion to the filtrate to coagulate and precipitate amine type nitrogen compound ions at a specific pH or more. CONSTITUTION:Raw waste liquid is received in a step 2 and SS is precipitated naturally as well as maintaining the pH of the waste liquid at about neutral point by Ca(OH)2 to precipitate Fe<3+> or Cr<3+>. A pH of a supernatant liquid in the step 2 is moreover raised in a step 3 to precipitate almost all metal ions and SO4<2->. Subsequently, in a step 4 for coagulating and precipitating amine type nitrogen compound ions, an inorg. coagulating agent containing Al ion is added to the treated waste liquid of the step 3 and, moreover, an alkaline agent is added to raise the pH to 10 or more to remove a considerable portion of amine type nitrogen compounds and fluorine. In this case, S2O6<2-> is also removed efficiently. The precipitate is subjected to heat treatment to be made disposable. The waste liquid of the step 4 is neutralized and filtered and, after COD is adjusted, discharged.</p> |
