Fine-coal-aided centrifugal C~2 dewatering of waste activated sludge

The centrifugal dewatering of waste activated sludges has been practiced for many years. Recently, there have been significant improvements in flocculants, notably the development of very high molecular weight organic polyelectrolytes. These flocculants produce durable floes, that are not readily broken up by the shearing forces in a centrifuge and that often reform if broken up. The improvements in the structure and performance of polymers were accompanied by advances in the de sign of centrifuges, from a processing efficiency stand point, as well as in mechanical dependability. These advances include the development of deep pool, slower speed machines with very low noise levels; lower power consumption; improved feed inlets to reduce turbu lence; co-current flow machines; low bowl/scroll differ entials with automatic speed control; and longer bowl length/diameter ratios to increase clarification capacity. Mechanically, substantial advances in material design and composition have reduced maintenance costs and downtime to a level highly competitive with alternative dewatering techniques. The newer advances in centrifuge technology, which eliminate the major deficiencies of past centrifuges; cou pled with the well-known and accepted advances of cen trifuges, have led to a renewed interest in using centri fuges for waste sludge dewatering. These known advan tages include low space requirements, enclosed opera tion, cleanliness, low operator attendance, and ease of operation and adjustment to meet changing feed con ditions.