Abstract: A rotary disk filter comprises a rotatable drum (2) and at least one disk-shaped filter member (10), which on the outside of the drum extends outwards in the transverse direction of the drum. The filter member (10) has a filter support unit (40) and a filter portion (21) supported thereby. A liquid duct (6) extends from the drum (2) through the filter member (10) and out through the filter portion (21). The filter portion is formed of at least one filter segment (20) which comprises a filter frame (22) and a filter cloth (21) expanded by the frame. The filter segment (20) is detachably secured to the filter support unit.