In Pretreatment, girt, paper and other large objects are removed from the water. The wastewater flows through a mechanical screen the removes the large objects from the water while washing the organic material back into the wastewater stream. The Rotomat Screen then compresses the excess water out of the screening and dumps them into a dumpster. Next the water is aerated and slowed so the grit can be settled out. Grit is things like egg shells, coffee grounds, dirt, etc. The grit is collected at the bottom of the aeration chamber and pumped through a water separating cyclone. After draining off the remaining water, an auger moves the grit in to a dumpster. Screening and grit are then hauled to the landfill for burial. Rotomat