Centrifugation Clarification and Thickening

Abstract

Since 1920, centrifuges have been employed in the US wastewater treatment industry. However, the early centrifuges did not perform well because of their complex design and poor mechanical reliability. In the early 1960s, a number of innovative designs were developed, which solved most of the operational problems. Sludge dewatering or thickening, and disposal of the residual solids, are significant costs of the waste treatment operation. These steps are especially important if the final disposal option is incineration. The incinerator will be more efficient if more water is removed prior to incineration. If the sludge has to be transported to a landfill, volume reduction owing to dewatering will significantly improve the overall economics (1--49). The sludge concentration methods of clarification, filtration, settling, flocculation, thickening, and centrifugation were evaluated. The choice of a dewatering technique is based on the feedstock, device design and function, and engineering specifications dependent on the intended outlook of the final products (47--48). Filter belt presses, solid-bowl centrifuges, and membrane filter presses were analyzed for their ability to dewater sludge according to their capacity, polymer consumption of dewatered dry solids, suspend solids in the reject water, and economics (49).