| 摘要 |
PROBLEM TO BE SOLVED: To provide an upward filtration apparatus which can directly filter raw water to remove fine turbidity matters and hardly causes filtration blockage with reduced cost.SOLUTION: An upward filtration apparatus (1) is constituted of a pressure container (2) and a granular filter medium (2). The granular filter medium (3) is constituted of a plurality layers having different particle diameters and stacked so that the particle diameter becomes smaller from the lower part toward the upper part. A layer (4) of the minimum particle diameter that is the uppermost layer is constituted of particles having a particle diameter of 1 to 50 μm. A porous plate, namely, an outflow preventing plate (9) composed of ceramic is provided on such the granular filter medium (3), thereby preventing the outflow of the granular filter medium. In addition, a washing pipe (17) for supplying washing water during backwashing is embedded in the layer (4) of the minimum particle diameter. |
