The mixture of water and sludge, fed by the central column, before being deflected by the baffle cylinder in order to facilitate the deposition of the solid sediments on the bottom, passes through the hydraulic sink where bacterial colonies begin to agglomerate into larger and larger size flakes. Deposited on the bottom, sludge is conveyed with the aid of the scraping blades , towards the openings of the suction pads, which convey the sludge in the appropriate intake manifolds, hence pass into the collection rotating chamber with siphon in the central zone of the column. Then will be extracted by suction primed for depression as a function of the required flow and recirculated in the head of the system. The clarified water touches the perimeter channel fitted with thomson profiles placed on the top of the tank. Any floating materials are retained by the baffle cylinder, or (optional) in case of need by a blade placed within the weir and conveyed to a and evacuation and collection tank (SCUM-BOX).