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|1. (WO2018047453) FILTRATION DEVICE|
The present invention relates to a filtration device having a plurality of filtration layers and using clean water sources such as river water, lake water, or groundwater or using water flowing out of sedimentation ponds, condensed water not passing through sedimentation ponds, industrial water, or wastewater treated water as raw water. The filtration device is provided with a filtration layer (40) that includes an anthracite layer (43), which is formed from an anthracite, and a silica sand layer (44), which is formed from silica sand having an effective diameter smaller than the anthracite and having higher density than the anthracite. The anthracite layer (43) has the same thickness as the silica sand layer (44) or is thicker than the silica sand layer (44), and the thickness of the filtration layer (40) as a whole exceeds 600 mm and is less than or equal to 2000 mm.