Grit is removed by a vortex type grit chamber. The unit is designed to remove grit down to 100-mesh size at sustained average flow up to 4 mgd with minimal carry over of organic material. The grit chamber consists of a circular cast in place of concrete chamber with a low speed-rotating paddle to enhance separation of grit and organic material. For reliability, a recessed impeller pump is used to remove settled grit from the grit chamber. Grit is discharged to a cyclone type separator followed by a screw type grit classifier to remove excess organic material and dewater the grit prior to discharge to a disposal cart. The grit pump and classifier are interlocked to operate together with operating frequency and duration controlled by an adjustable timer.