| 摘要 |
In a waste water ground filter consists of a filter layer on top of a drainage layer. The two layers are separated by a boundary layer with a relief profile. The drainage layer is raised above the drainage pipes and the lower side of the filter layer is deeper between the drainage pipes, creating an inclined capillary suction layer. A waste water ground filter consists of a filter layer on top of a drainage layer. The two layers are separated by a boundary layer with a relief profile. The drainage layer is raised above the drainage pipes and the lower side of the filter layer is deeper between the drainage pipes, creating an inclined capillary suction layer. The height difference between the top and bottom of the capillary suction layer is greater than the capillary rising height in the filter layer when, at its field capacity. The typical filter charge depth on the filter upper face with respect to the maximum retained depth, is greater than the de-watering pressure capillary margin in the lower part of the filter layer. The drainage system is subjected to either pressure or suction in comparison with the atmosphere.
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