The invention relates to a rotary separation unit, comprising a rotor housing with a feeding zone (A), a separation zone (B) and a discharge zone(C), parts of the circumferential housing being closed and other parts having openings, a rotary driven separation rotor arranged in said rotor housing, beater plates fixed on said separation rotor, and sucking air flow generating means sucking an air flow stream from the discharge zone (C) through the rotor housing, characterized in that the beater plates have at least one opening in their structure which allow an air flow stream to pass through.