| 摘要 |
PROBLEM TO BE SOLVED: To provide a dephosphorizing method and a device therefore by which the generating quantity of fine crystals is small even in an unstable region and crystallization can be executed in a short time in a high removing ratio by using a small quantity of crystal seeds and at a high crystallization speed. SOLUTION: In the dephosphorizing method in which a phosphor-containing water is brought into contact with a fluidized bed of the crystal seeds in the presence of calcium ions, and phosphor is removed by crystallization, the fluidized bed of the crystal seeds is formed by making water to be treated pass in a crystallization tank upward, an alkali and/or a calcium compound are added to the fluidized bed to cause reaction and a reaction liquid in the unstable region is generated, the reaction liquid in the unstable region is brought into contact with the crystal seeds to crystallize crystal of calcium phosphate on its surface to obtain treated water having 9.5 to 12 pH, <=1 mg/l calcium ion concentration and <=1 mg/l total phosphor concentration.
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