| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method and an apparatus for treating inorganic ion-containing waste water, in each of which sludge, that is made dense and has high dewaterability and a high precipitation rate, can be produced.SOLUTION: The method for treating inorganic ion-containing waste water comprises the steps of: adding insolubilized material producing agent-added return sludge to the inorganic ion-containing waste water to precipitate the insolubilized material; subjecting the insolubilized material-precipitated return sludge-added waste water to solid-liquid separation treatment to separate the insolubilized material-containing sludge from the treated water; using a part of the separated sludge as the return sludge; adding an insolubilized material producing agent to the return sludge; adding the insolubilized material producing agent-added return sludge to the inorganic ion-containing waste water; and discharging the remainder of the separated sludge as the sludge to be withdrawn. A cationic polymer flocculant having 10-50 mol% cationic group ratio is added to the insolubilized material producing agent-added return sludge-added inorganic ion-containing waste water and the flocculant-added waste water is agitated to produce flocculated flocks, and further an anionic polymer flocculant is added to the flocculated flock-produced waste water to granulate the flocculated flocks.</p> |
