| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a grit tank stably removing grit with simple structure without the need of disposing a machine device or the like in underwater. Ž<P>SOLUTION: The appropriate number of jetting nozzles 8 for jetting water to a sand collecting pit 7 formed on the bottom surface 6a of the grit tank 6 are disposed, and a sand blocking weir 20 is disposed downstream of the jetting nozzles 8. The sucking operation of sewage by a jet pump 9 whose suction port is disposed at the sand collecting pit 7 and the jetting of the water by the jetting nozzles 8 are almost simultaneously performed. The water lifting amount of the jet pump 9 and the jetting water amount from the jetting nozzles 8 are made almost equal. On the downstream side of the jetting nozzles 8, the sand blocking weir 20 of an appropriate height is installed. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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