A rotary drum solid waste air classifier includes an inclined drum in which is mounted a non-rotatable separation enhancing tube which extends longitudinally completely through the drum. A waste conveyor is longitudinally mounted within the tube. The feed end of the waste conveyor is located outwardly of the lower end of the tube for receiving solid waste and conveying it through the rotating drum. The tube has a delivery cut-out at and below the discharge end of the waste conveyor so that the waste may fall from the discharge end of the waste conveyor and the discharge from the lower end of the drum while the light fraction flows up the drum and into a plenum downstream from the drum.