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Wastewater Treatment
Published in Charles R. Rhyner, Leander J. Schwartz, Robert B. Wenger, Mary G. Kohrell, Waste Management and Resource Recovery, 2017
Charles R. Rhyner, Leander J. Schwartz, Robert B. Wenger, Mary G. Kohrell
The application of centrifugation to wastewater treatment dates back more than 50 years. Early centrifuges were primarily designed for industrial processing and were not well suited for the variable characteristics of wastewater sludges. Hence their early use in wastewater treatment plants was associated with significant operational and maintenance problems. Since the 1960s, centrifuge designs have appeared that are more troublefree in dealing with the unique and variable properties of sewage sludges. Two examples of centrifuges used for sludge thickening are the imperforate basket centrifuge and the solid bowl decanter centrifuge. In Figures 6.7 and 6.8 diagrams of their basic designs are shown. The advantages and disadvantages of each are compared in Table 6.5.
Advances in Algae Dewatering Technologies
Published in Shusheng Pang, Sankar Bhattacharya, Junjie Yan, Drying of Biomass, Biosolids, and Coal, 2019
K.Y. Show, Yuegen Yan, D.J. Lee
Solid-bowl decanter centrifuge features by a conical-shaped bowl placed horizontally which consists of a screw conveyor that rotates in parallel with the bowl. Slurry is fed through the center shaft and is spun towards the bowl circumference. Spun solids are pulled by the screw conveyor to one side of the bowl for discharge, while clarified liquid forms a concentric inner stratification which flows over an adjustable weir for discharge. The helical screw conveyor that pushes the centrifuged solids operates at a higher rotational velocity than the bowl.
Advances in dewatering and drying in mineral processing
Published in Drying Technology, 2021
Benitta A. Chaedir, Jundika C. Kurnia, Agus P. Sasmito, Arun S. Mujumdar
Beside hydrocyclones, there are also many industrial centrifuges types that play a key role in solid-liquid separation processes. While they are significantly more expensive and complex, centrifuges offer better separation performance and greater flexibility than hydrocyclones.[3] One type of these centrifuges that is frequently used is decanter centrifuge. This centrifuge consists of two distinctive components; i.e., solid wall enclosure (the bowl) and the conveyor scroll inside to drive and segregate the mineral slurry, as shown in Figure 3. The cylindrical-conical bowl shell revolves at a high speed to induce centrifugal force required for separation process. Typically, the bowl diameter ranges from 0.2 m to 1.4 m depending on the separation capacity required. A conveyor scroll is contained inside the bowl for continuous discharge and it rotates at a speed relative to the speed of the enclosure. The feed slurry is fed via the center tube of the rotating screw conveyor and is subjected to a high centrifugal force, pushing the solids to settle at the outer section. These separated solids are pushed by the conveyor scroll out of the liquid and discharged at the solid outlet.[3] Throughputs of the centrifuge vary depending on feed concentration, which varies in the range from 0.5% to 70% solids, with 5–20% of water content in the solid product. An advantage of the decanter centrifuge is its continuous process and its capability to segregate suspension that contains small amount of liquid and high concentration of solid material.[17] However, decanter centrifuge possess lower G-forces than tubular and disk centrifuges and it has smaller surface area than disk centrifuges. In designing a decanter centrifuge for specific applications, critical parameters that are critical to its performance such as length-diameter ratio, vibrations, and temperature must be considered.