| 摘要 |
The present invention has an object to provide a filtration apparatus and a filtration method which can treat a large quantity of flow in a short time and can sterilize raw water to a high level using only a physical treatment. The filtration apparatus and the filtration method according to the present invention includes a spring filter 2, a first precoat layer A of a filter aid 41 disposed on an upstream side thereof, and a second precoat layer B of a filter aid 42, and causes raw water to flow from a side of the second precoat layer B to carry out a filtration, and is characterized in that the filter aid 41 has a particle size distribution primarily including coarse particles which, due to a flow during a water transfer, aggregate at the openings to cover and form bridges over said openings with multiple pieces, whereas the filter aid 42 has a particle size distribution primarily including fine particles, which are smaller than the filter aid 41 and which themselves cannot form bridges over the openings, and in that the openings of the spring filter 2 and the particles of the second precoat layer B are adjusted in size by the first precoat layer A, which is held by the spring filter 2 due to bridging phenomenon.
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