| 摘要 |
PROBLEM TO BE SOLVED: To control the concentration of residual chlorine in water to be treated within a specified value not to adversely affect environment by preventing the occurrence of excess chlorine injection either when a rainfall at an average level continues for a long time or when the rainfall occurs semi-continuously. SOLUTION: When the rainfall occurs semi-continuously, the flow rate of confluence sewage flowing into a rain water pump well 3 through a sewage inflow gate 2 is reduced and a rain water discharge pump 4 is temporarily terminated, during a confluence sewage determination part 7a determines it as a similar rainfall, the time-based operation of a timer is continued by a chlorine injection controller 9a and a control target value (hypochlorous acid injection ratio which is decreased stepwise as time passes) corresponding to the lapse time of the rainfall obtained by the timer is used. COPYRIGHT: (C)2007,JPO&INPIT
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