| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for treating wastewater containing fluorine capable of preventing the deposition of minute particles of calcium fluoride, and obtaining a stable water quality treated through only a small number of processes and sludge having a low water content. SOLUTION: The method treats the wastewater containing fluorine with a series two-stage reaction tank. A calcium compound in an amount less than the equivalence of the fluoride ions in the raw water is charged into a first reaction tank so as to make the calcium ion concentration 1 to 50 mg/L and a fluoride ion concentration less than 80 mg/L to be retained after the reaction. Next, a calcium compound in an amount more than the equivalence of the fluoride ions retained in the first reaction tank is charged into a second reaction tank so as to make the fluoride ion concentration in the second reaction tank less than 15 mg/L. Produced sludge is separated, mixed with alkali, and returned to the first reaction tank as alkali sludge. COPYRIGHT: (C)2009,JPO&INPIT
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