| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method and device for treating organic waste water, capable of suppressing the increase in filtration resistance by using the whole filter material effectively to reduce the washing frequency of a filter material layer and the generating amount of washing waste water. SOLUTION: This method for treating organic waste water cleans organic waste water 11 under an aerobic condition by a fixed-bed, descending flow type biomembrane filtration method. The biomembrane filtration method has a porous member 2 above the filter material layer and under the surface of water. Multilayered filter material layers 3, 6 where the true densities of the filter materials 4, 7 are different from each other are installed under the porous member. In the filter material layer 3 that forms an uppermost layer, the true density of the granular filter material 4 is made to be lower than that of water, thereby the uppermost layer forms a floating fixed filtration layer under the surface of water in the case that water passes and each of the granular filter materials is made to move independently in the case that the device is washed. Preferably, the average dimension D1 of the air gap in the layer 3 is made to be larger than the average dimension D2 of the air gap in the layer 6 and the porosity E1 of the layer 3 is made to be larger than the porosity E2 of the lower layer 6.</p> |
