the frame 14 can be made of metal preferably stainless steel for sealing of the filter segment 13 against the filter support 4 the frame 14 may be enclosed by a rubber strip for example epdm rubber in order to facilitate insertion and removal of the filter segments 13 in the grooves 22 the outside of the rubber strip may be flocked which reduces friction against the filter support 11 the seal may also be promoted by the filter segments 13 as the liquid a passes out through the filter cloth 4 being pressed outwards by the liquid pressure so that the frame 14 is pressed against the outer boundary walls of the grooves 22 and 23 in one embodiment the filter cloth 4 which is expanded by the frame 14 may be a microfilter cloth with filter holes in the range 10 100 u03bcm the filter cloth 4 may be selected according to the filtering capacity that is required the inventive rotary disc filter can suitably be cleaned by means of a cleaning device for example the cleaning device described in se c 515 001 wo 00 37159 it will be appreciated that many modifications of the embodiments of the invention described above are feasible within the scope of the invention which is defined in the appended.