Schreiber handles sludge treatment with a unique all-in-one digester and thickener configuration. Termed the GRS, it consists of a central circular thickener surrounded by an aerobic digester in the form of a concentric annular ring.
One advantage of the GRS digester/thickener configuration is that it optimizes the space required for sludge treatment. It is very structurally efficient and offers the advantages of common wall construction. The Schreiber automatic DO control based aeration system, along with its high-efficiency mechanical mixing, results in power savings of 50% to 80% over conventional aerobic digesters.
While the sludge is stabilized in the outer digester, it is transferred to the thickener section by gravity. In the thickener, the sludge compacts via gravity and the peripheral-drive helical scrapers transport the thickened sludge to a central hopper for withdrawal. The thickened sludge is either returned to the digester to increase the solids concentration, or it is wasted to dewatering or further processing.