A grit removal apparatus has a central opening between a cylindrical separation chamber above a grit storage chamber. An influent flume introduces a liquid stream directly into a lower portion of the periphery of the separation chamber, and an effluent flume removes a stream through an opening in an upper portion of the separation chamber wall. Outwardly spiraling vanes extend upwardly at the bottom center of the separation chamber, and a vertical cylindrical duct is supported above the vanes. A tunnel is defined in the separation chamber by an upper wall at the bottom of that opening and an inner wall concentric with the separation chamber wall. A ring extends inwardly from the separation chamber wall, with the tunnel upper wall defining a portion of the ring. A propeller inside the duct rotates to draw fluid flow up through the duct toward the upper portion of the separation chamber.