| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for filtering confluent sewage at a high speed, by which the majority of a filthy solid substance can be removed even when a large quantity od rainwater is flowed and a backwashing operation can be performed quickly. <P>SOLUTION: The confluent sewage is introduced into a plurality of upward stream type filtration tanks 1 the top surface of each of which is used as a common treated water tank 5 and filtered at a high filtration speed of 1,000-1,200 m/day by using a floating filter medium 4 which is packed in each of the tanks 1 and has 0.1-0.4 bulk density. When the medium 4 is clogged in any of the tanks 1, the supply of an original water to the tank 1 to be washed is stopped and the tank 1 to be washed is backwashed by making the treated water in the tank 5 flow downward into the tank 1 to be washed at the speed of 1.2-4.0 m/minute. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
