| 摘要 |
PROBLEM TO BE SOLVED: To obtain treated water, from which fluorine is sufficiently removed, by stably and efficiently treating fluorine-containing wastewater with aluminum coexistence using a calcium fluoride method. SOLUTION: A calcium compound is added to the fluorine-containing wastewater with aluminum coexistence while phosphoric ions are further added so that P/Al (molar ratio) becomes 1 or above and insoluble matter is subjected to solid-liquid separation under a condition of pH of 3.5-5.5. It is preferable to return the sludge obtained by solid-liquid separation to a reaction process. At this time, it is preferable that the calcium compound to be added to raw water is preliminarily mixed with the return sludge and the modified sludge is added to the raw water. COPYRIGHT: (C)2007,JPO&INPIT
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