| 摘要 |
PURPOSE:To treat the amount of raw water for filtration to be treated which is fed to all filters without providing a spare equipment by performing control incorporating such operation that the water level of a raw water tank for filtration is reduced a constant amount before one set of filter starts a backwash process. CONSTITUTION:Raw water for filtration stored in a raw water tank 1 is sent to the filters 14-17 with a raw water pump 4 to filter and treat it and thereafter stored in a treated water tank 3. When one set of filter starts a backwash process, the filter starting backwash is selected by the operation of automatic valves 19 via a pipeline 12 by means of a backwash pump 5 provided in the treated water tank 3 and one part of the treated water is fed to perform backwash and drainage of backwash is stored in a drainage tank 2 of backwash via a pipeline 13. At this time, three sets of residual filters intactly receive raw water fed from the raw water pump 4 and perform a filtering process. These operations are performed by controlling the raw water pump 4, the backwash pump 5 and the automatic valves 19 by means of a filter controller 18.
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