The GRR grind is constits of stainless steel case with a drum filter made of wedge wire rotating in. The wastewater flows inside the feeding tank through a flanged spout and it is conveyed on the external surface of the filtering drum by a special distributor. The cleaned water get through the filtering surface toward the outlet spout, while the solid particles remain on the rotary drum surface and they are subsequently removed by a fix blame placed at the opposite side of the drum. The filtering is kept clean by a washing system. The filtering part is ready to repeate the cycle at every turn since it is particleless.