A rotary filter comprises (i)a shell,(ii) a control head,(iii) a filter drum and (iv) a device for transferring the washing fluid from the washing output areas to the previous washing input areas of the washing areas in a manner of being reverse with the rotation direction of the filter drum, wherein the shell comprises a first washing area, a final washing area and one or more mediate washing area, the first washing area comprsies a first washing fluid input area, the final washing area comprises a final washing fluid input area, and the mediate washing areas respectively comprise the washing fluid input areas; the control head comprises a first washing fluid output area, a final washing fluid output area and one or more mediate washing fluid output areas; the filter drum is located in the shell and can rotate in the shell around the axis of the filter drum; the device is characterized in that the rotary filter is configured to flow the washing fluid from the washing fluid input areas (Izn) to the washing fluid output area (Ozn) via the filter drum and via a same washing area (n), and additionally flow to the washing fluid output areas of the previous washing areas.