Method for operating filtration device

A method for operating a filtration device, wherein the filtration device comprises:

• a filter element having a filter medium constituted of a metal mesh material, in which during filtration to pass a fluid from one surface side to the other surface side of the filter medium, substances in the fluid are captured on the one surface, and during backwashing to pass a fluid from the other surface side to the one surface side of the filter medium, the captured substances are separated from the filter medium;
• a brush arranged to be capable of making a relative movement with respect to the one surface of the filter medium and assisting in separating the captured substances and sifting with respect to the captured substances during the relative movement;
• a driving motor causing the brush or the filter element to rotate;
• a filtration mechanism passing a fluid from the one surface side to the other surface side of the filter medium and a backwashing mechanism passing a fluid from the other surface side to the one surface side of the filter medium;
• a casing supporting at least the filter element, the filtration mechanism, and the backwashing mechanism;
• and
• a control unit controlling the driving motor, the filtration mechanism, and the backwashing mechanism, wherein the operating method of a filtration device comprises starting the backwashing when a differential pressure between both surfaces of the filter medium exceeds a predetermined value or as triggered by a lapse of a predetermined time while performing the filtration, and returning to the filtration after the differential pressure is eliminated or after a predetermined time elapses, and
• wherein, the control unit, while the fluid passes through the filter medium during both the filtering and the backwashing, by controlling the driving motor so as to cause of the brush or the filter element to rotate, cause the filter element to relatively move with respect to the filter medium so as to cause the brush to perform brushing and the control unit, during the filtering, performs a sifting operation of crushing the captured substances by brushing performed by the brush, sifting removal unnecessary substances from the captured substances and passing the removal unnecessary substances to the other surface side.