A grit removal device, as may be used in a water or wastewater treatment plant, has a vortex grit collector and a mechanical conveyor for removing the grit from the collector. The grit collector includes a tank having an influent channel and an effluent channel, and a stirrer or other mechanism for inducing vortex flow within the tank. The tank has a sump located beneath it, wherein grit settles. A mechanical conveyor, such as a rotating screw, removes and dewaters grit from the sump to an exterior location. The conveyor is preferably offset from the horizontal. The invention also includes a method of grit removal employing the device.