| 摘要 |
<p>PURPOSE:To extend washing cycle, by combining a fist constitutional filter material having a void ratio made large by making crossing density coarse to form large voids with a second constitutional filter material of which the crossing density is lowered and the void ratio is reduced more than the first constitutional filter material. CONSTITUTION:Filter materials 2 having a large void ratio epsilon and filter materials 3 having a small void ratio epsilon are alternately stacked to form a laminated filter material and a supply pipe 6 is provided in opposed relation to the upstream side of the flow passage of the filter material while a discharge pipe 7 is provided in the downstream side of the flow passage 4' offset to the other side of the filter material. When raw water is supplied to the filter materials 2, the greater part of said water is sent to the discharge pipe 7 through the flow passage 4. A part of the raw water passes through the filter materials 3 to be discharged to the discharge pipe 7. The raw water is formed into minute branched streams in the filter materials 3 and bacteria are propagated and the org. substance collected in the circumference of the flow passage 4 is decomposed. By this method, no clogging is generated over a long period of time and a washing cycle can be extended.</p> |
