| 摘要 |
PURPOSE:To remove phosphates, by forming a fluidized bed in a bed expansion ratio range of 20-100% and intermittently withdrawing grown solid particles from a packed tower so as to hold 50% or more of a bed expansion range while replenishing solid particles with a small particle size to said tower. CONSTITUTION:A dephosphorization tower 6 is packed with solid particles such as phosphate rock particles with a particle size of 0.2-1.0mm and a liquid to be treated and recirculation water are supplied to said tower 6 from the lower part thereof at such a liquid passing speed that a solid fluidized bed 7 is fluidized. The fluidized bed 7 is formed so that the solid particle bed is fluidized in an expansion ratio range of 20-100%. Because the fluidized bed is enlarged with the advance of treatment, a part of the solid particle bed 7 is intermittently withdrawn from the solid particle withdrawal pipe 13 provided to the upper part of the tower 6 and solid particles having a particle size smaller than that of the withdrawn solid particles are replenished to the solid particle supply pipe 13 provided to the upper part of the tower 6.
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