| 摘要 |
PURPOSE:To prevent the clogging of the upper layer and to use a filter medium layer contg. suspended matter collected therein as a filtration layer with fine meshes by constituting a moving bed structure, and depositing a filter medium over the upper layer part wherein suspended matter is collected to use as a fresh upper layer part. CONSTITUTION:The polluted water in a polluted water tank 16 is supplied to the upper part of a collecting cylinder 3 by a pump 17. The supplied polluted water is passed through a filter medium B, collected in a water collecting chamber 2, and stored in a water collecting tank 18. When the clogging of the filter medium is increased, a solenoid valve V1 provided to a filter medium discharging port 1 at the lower part of the collecting cylinder is opened and a pump 4 for sucking and sending the filter medium is operated. The filter medium is returned to the upper part of the collecting cylinder 3 through a return pipe 5 for washing the filter medium, and a fresh filter medium layer is formed over the upper layer of the filter medium which is clogged to some extent. Then the filtration and collection of water are restarted. When the original upper layer is successively lowered, the whole filter medium is washed by passing through the return pipe 5 for washing the filter medium, and returned to the inside of the collecting cylinder 3 through a solid-liquid separation device 7 to form the filter bed.
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