| 摘要 |
A slow sand filter system having a slow sand filter located under water and a scraping mechanism. The scraping mechanism has at least one auger and a shaft, the auger extending across the width of the slow sand filter and being supported in the center thereof by the shaft such that the auger is horizontal. The auger may have a shroud located along the length of the auger and spaced therefrom. The auger moves the schmutzdecke layer across the slow sand filter. The slow sand filter system may have recycle, to permit passing water through the slow sand filter system at a rate less than the maximum vertical flow rate and recycle of a portion of said water passing through the slow sand filter system back to the body of water and removal of the remainder of the water to another location. The method permits operation of the slow sand filter system to provide a variable supply of water without minimal disruption of the filter system.
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