| 摘要 |
PURPOSE:To hold the dephosphorizing power of the titled apparatus constant, by constituting one or more catalytic beds composed of crystal seeds containing calcium phosphate inside a disposal column with porous supporting plates at one or more stages along a vertical direction, and providing a means for discharging treated water thereon. CONSTITUTION:In order to detect the upper surface of the lowermost-stage catalytic bed 2 under a fluidized condition, a level sensor 6, e.g. an optical, ultrasonic or specific electric resistance sensor, capable of distinguishing the fluidixed catalytic bed 2 and the layer of water thereabove from each other is provided at a position below a supporting plate for the catalytic bed 2 of the second stage from the bottom inside the column. In order to detect the expansion of the lowermost-stage catalytic bed 2 caused by a pressure loss, the change of a pressure loss between the catalytic beds of the lowermost stage and the second stage from the bottom or a much upper stage is measured by a differential pressure gauge 7. The differential pressure gauge 7 may be provided outside the column, and the catalytic beds of the lowermost stage and the upper stage to be compared therewith are connected through piping 8 to said gauge 7.
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