| 摘要 |
<p>PURPOSE:To discharge only backwashing water and impurities and to easily prevent the outflow of a filter medium by separating a contact tank into plural chambers by a partition wall, providing a biological filter bed in each chamber, connecting a backwashing water inlet pipe to each chamber, and furnishing a backwashing water outlet pipe in the vicinity of the surface layer of the filter bed in each chamber. CONSTITUTION:The contact tank 1 is separated into two chambers A and B by the partition wall 12. When the biological filter bed 3 in the chamber A is washed, the valve 11 of the backwashing water outlet pipe 10 of the chamber A is closed, and the valve 11a of the backwashing water outlet pipe 10a of the chamber B is opened. Under such conditions, backwashing water is introduced from the backwashing water inlet pipe 8 of the chamber A, and the filter bed 3 in the chamber A is washed. When the water level in the chamber A rises along with washing, the backwashing water contg. a part of the circulated filter medium 4 flows into the adjacent chamber B past the partition wall 12. In this case, the relatively heavy filter medium 4 settles in the filter bed 4a of the chamber B, and only backwashing water and the lightweight impurities contained in the backwashing water are discharged from the outlet pipe 10a. The filter bed 3a of the chamber B is washed in the same way.</p> |
