| 摘要 |
PROBLEM TO BE SOLVED: To filter general waste water by a simple apparatus to easily reutilize the same. SOLUTION: A basket-shaped filter bed 3 formed from a stainless steel perforated plate permitting the passage of water but blocking the passage of impurities is provided in a filter apparatus 1 and the perforated plate is produced by an etching technique covering a stainless steel plate with an anticorrosive mask having a large number of pores to corrode the same with an acid to make perforations in the stainless steel plate. The primary filter bed 3 being the basket-shaped filter bed and a secondary filter bed 4 being a sandwich- shaped filter bed wherein fine particles of spherical activated carbon are held between two polyolefin foam plates to be heated and molded are provided to the filter apparatus 1. Further, forcible filter means (12, 14, 18) for temporarily pressurizing the surface S of the water in the filter apparatus by compressed air are provided in order to compensate the lowering of the filtering capacity of the filter apparatus. Further, a means 5 for detecting the height of the surface of the water is provided to the filter apparatus and the supply of compressed air to the filter apparatus is controlled by the output of this detection means.
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