An interior wedge wire drum screen is mounted wholly within an exterior drum screen of narrower wedge wire spacing, and both are mounted to a frame and caused to rotate about a common central axis. One end of the outer drum is open and the other is closed by a disc-shaped drum head. The inner drum has an open end which is spaced inward of the open end of the outer drum. The waste water is presented to the surface of the inner drum screen by a waste water infeed which employs a vertical column. The column extends upwardly of an inlet and has a gradually increasing cross-section for reducing the flow of velocity of the waste water. A horizontal trough extends along the axis defined by the drums and communicates between the top of the column and a tray. The edges of the tray terminate in weirs which are parallel to the sides of the inner drum. Water flows in a smooth sheet over a weir to impact the sides of the inner screen with low velocity. As the drums rotate the accumulating residue is moved by a spiral auger which progresses the filtered material to the open ends of the drums. The material from the inner drum falls to the surface of the outer drum, and is progressed to a waste collection trough.