| 摘要 |
<p>PURPOSE:To enable backwashing of a packed bed without storing backwashing water by performing backwashing of the packed bed successively while keeping an upper section of the packed bed in a partition wall separated into blocks at a negative pressure. CONSTITUTION:When filter layers 6 are back-washed successively in case of raised filtration resistance, a movable U-shaped back-washing cylinder 9 having a size corresponding to the size of a block is inserted into a fixed partition wall 5 and fitted air-tightly thereto with a seal 14 at the top of a filter layer 6 among plural numbers of chamber of filter layer 6 constructed by separating a packed filter medium 4 with fixed partition walls 5. A top end of the backwashing cylinder 9 is sealed with water and one 10 of branched pipes of the backwashing cylinder 9 is connected to a siphon breaker. Under this condition, the inside of the backwashing cylinder 9 is evacuated, and clean water in a clean water duct 7 is flowed as backwashing water in the direction expressed by an arrow mark, and the filter layer 6 is back-washed. The clean water is transported to a pit 12 through a siphon communicating pipe 11 and discharged from an exhaust waver pipe 13. After completing the backwashing operation, the U-shaped backwashing cylinders 9 are moved successively to above the filter layer 6 of each chamber, and the filter layers 6 are back-washed successively.</p> |
