Hydrocyclones are used in biogas plants to separate solid inclusions from substrates: sand, soil, mineral sediments and small stones. Substrate is fed into the upper part of the hydrocyclone in the tangential direction. Centrifugal acceleration causes the particles to move to the separating cone wall, from where they sink into the dirt trap through an intermediate pipe, followed by the clean substrate being discharged from the upper part of the separator in the axial direction. Also, the vortex movement of the suspension creates a vacuum zone, which entrains the purified part of the internal flow and brings it further for technological needs. Two manholes in the dirt trap are available to control the sinking process. Heavy particles are removed by the addition of recycled water to the dirt trap. High adaptability to any level of substrate contamination is achieved by adjusting the valve and dirt trap cycles.