METHOD AND SYSTEM FOR TREATING FLUORINE-CONTAINING WASTE WATER

PROBLEM TO BE SOLVED: To provide a method and a system for treating fluorine-containing waste water, in each of which a large amount of a flocculant is not required.SOLUTION: The method for treating fluorine-containing waste water comprises: a calcium fluoride production step of adding a calcium compound to the fluorine-containing waste water to produce a suspension including a calcium fluoride-containing solid; a condensation circulation step of supplying the produced suspension to a circulation route 23 having a separation membrane 3c to obtain a concentrated liquid, in which the concentration of the calcium fluoride-containing solid is increased, and separation membrane 3c-permeated treated water; a fluorine concentration detection step of detecting the fluorine concentration of the obtained treated water; a concentrated liquid discharge step of discharging a part of the obtained concentrated liquid to the outside; a solid concentration detection step of detecting the concentration of the calcium fluoride-containing solid; and a solid concentration adjustment step of adjusting the amount of the concentrated liquid to be discharged so that the concentration of the calcium fluoride-containing solid becomes a first reference value. When the detected fluorine concentration exceeds a second reference value, the first reference value is increased and the amount of the concentrated liquid to be discharged is adjusted again. 【課題】大量の凝集剤を必要としないフッ素含有排水処理方法及びフッ素含有排水処理システムを提供する。【解決手段】フッ素含有排水処理方法では、フッ素含有排水にカルシウム化合物を加えて、フッ化カルシウム含有固形物を含む懸濁液を生成するフッ化カルシウム生成工程と、分離膜３ｃを有する循環経路２３へ懸濁液を供給し、フッ化カルシウム含有固形物の濃度を高めた濃縮液と分離膜３ｃを透過した処理水とを得る濃縮循環工程と、処理水のフッ素濃度を検出するフッ素濃度検出工程と、濃縮液の一部を系外に排出する濃縮液排出工程と、フッ化カルシウム含有固形物の濃度を検出する固形物濃度検出工程と、フッ化カルシウム含有固形物の濃度が第１基準値になるように、濃縮液の排出量を調整する固形物濃度調整工程と、を備え、フッ素濃度が第２基準値を上回る場合は、第１基準値を増加させる調整を行う。【選択図】図１