| 摘要 |
<p>PROBLEM TO BE SOLVED: To make the whole of a filter medium layer or a portion easy to be fluidized and to enable uniform biological filtering with the whole filter medium layer by filling the filter medium layer formed a biological film on floating filter medium having a specific range of density in a filter tank, floating one portion on a water surface and also forming a contact region with liquid to be treated with an underwater portion. SOLUTION: The floating filter medium having specific density of >=0.5 and <=1.0 and filled in the filtering tank 1 and the filter medium layer 2 consisting of a contact area 4 in water and a floating area 5, is formed. A diffuser 10 is provided under the filter medium layer 2, and the air fed from an air feed path 11 is diffused. Also, the filter tank 1 is connected with a treating liquid path 12 at the lower part and the bottom is connected with a washing discharging liquid path 13 and a strainer 14 is provided on the contact area 4 and connected with a treated liquid path 15 and a liquid to be treated is introduced from the treating liquid path 12 and is passed through the contact area 4 in an uppercount flow. Thus, SS in the liquid to be treated is caught at the contact area 4 and dissolved organic-matters, etc., are decomposed and eliminated with microorganisms and the treated liquid is discharged from the treated liquid path 15 in a state prevented from flowing out the filter medium with the strainer 14.</p> |
