The invention refers to a filter segment for use in a filtration device, especially a rotating filter for filtering liquids with a frame element (1) made at least partly of plastic and a filtration surface enclosing it, in which at least a flat filter material (2) spanning the filtration surface is embedded. According to the invention, it is suggested that within the frame element (1) at least one reinforcement (3) is arranged, for example, like a reinforcement frame and/or individual reinforcing elements traversing the entire frame element (1). Furthermore, the object of the invention is a circular segment for holding a minimum of one filter segment for use in a filtration device, especially a rotating filter for filtering liquids, whereby the circular segment has two opposing lateral sections, each one having one inner surface (11) for guiding the filter segment and a corresponding outer surface (9) executed as an adjacent surface for the corresponding outer surface (9) of another circular segment—and, in this case, the circular segment consists of detachable individual elements (6) linked to one another. The circular segment is finally characterized by the fact that at least two of the individual elements (6) have the same kind of structure.