| 摘要 |
The backwashable rapid filter unit has a plurality of filter zones (8). During backwashing, the level or pressure difference (A-B) between an overflow edge (9) for the clean water and sludge orifices (10) in each filter zone (8) force the clean water serving as flushing water from a communicating system of buffer chambers (6) containing clean water through each filter zone (8) to be flushed. The flushing water flows simultaneously against the filtering direction always through only one filter zone (8) to be backwashed, while the remaining zones (8) operate in the filtering mode. The difference in levels (A and B) is matched to the necessary amount of flushing water in this case; it is selected so that a sufficient, but not too large, quantity of water is always available as flushing water. The number of the filter zones (8) of the unit exceeds the ratio of backwash to filtering rate by at least one unit, so that during a backwash procedure, at least as much clean water is generated as is required for backwashing. As a result of the concept of the unit illustrated, the expenditure required for backwashing is considerably reduced. <IMAGE> |
