DYNAMIC FILTER

PROBLEM TO BE SOLVED: To solve a problem of a dynamic filter using the water level difference between the water level of a biological reaction tank and the water level of a releasing end of a filtered water discharge pipe that the water level difference is remarkably varied and suitable filtered flux density is not maintained when the water level of the biological reaction tank is remarkably varied. SOLUTION: In a dynamic filter device having a filter fabric having an aperture capable of substantially passing suspended particles, filtering suspended particles-containing water by forming a dynamic filter layer on the surface of the filter fabric and immersing a filter body for taking out filtered water from a filtered water discharge pipe in a water tank housing the suspended particles-containing water, and in the dynamic filter for filtering the suspended particles-containing water by using the water level difference between the water level of the water tank and the water level of the releasing end of the filtered water discharge pipe as driving force, the releasing end is faced to a water collection trough having a movable weir and capable of changing the water level.