External device for cleaning filtration material and adapted for application to filtration device

An external device for cleaning a filtration material and adapted for application to a filtration device, which filtration device is provided with a filtration container having layers of a filtration material at the inside and is adapted for filtering a supplied unfiltered liquid by the layers of the filtration material to remove muddiness in the liquid and discharging the cleaned liquid to the outside, the cleaning device comprising:

• i) an upstanding outer tube,
• ii) a screw conveyor rotatably placed in the outer tube and transferring the filtration material upward from an inlet at a lower end section of the outer tube to an outlet at an upper end section of the outer tube, while rub-washing the filtration material,
• iii) a drive section for rotationally driving the screw conveyor,
• iv) a control section for controlling rotation of the drive section,
• v) an introduction tube, which is connected to the inlet of the outer tube and introduces the filtration material from the inside of the filtration container into the outer tube, and
• vi) a discharge tube, which is connected to the outlet of the outer tube and discharges the filtration material, having been rub-washed, from the inside of the outer tube into the filtration container.