| 摘要 |
<p>PURPOSE:To improve the quality of purified water better than that in the past, by using a floating filter, which can be easily washed in case of clogging even if it has a small particle size, as a filter forming a filter bed layer in a trickling filter vessel. CONSTITUTION: A floating filter 2 having a specific gravity smaller than 1.0, e.g. small particle-sized foamed styrene, foamed PP or pearlite, is packed in a trickling filter vessel 1, to form a filter bed layer 5. Crude water 3' is sprayed to the surface part of the layer 5 from a rotary sprinkler 4, and let flow through the layer 5. The interior of the vessel 1 is ventilated by natural or forced air blow, to feed oxygen to bacteria adherent on the surface of the filter 2. The water 7' biologically purified by the layer 5 is partially returned through a circulating flow line 14, and the remainder is disposed as drain 15. With advancement of the treatment, the layer 5 is clogged by proliferation of the bacteria. At this time, an effluent amount is maintained smaller than an influent amount by a control valve 9. The water head inside the vessel 1 rises, the filter 2 begins floating and finally floats as a whole, but the floatation is restricted by a member 8. Breeded bacteria and a collected SS part are stripped and removed from the filte by effects of contact, friction and swinging during the floatation. After washing is completed, the valve 9 is fully opened.</p> |
