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Publisher Summary This chapter introduces the key issues involved in the design of sludge pumping systems. The key to pumping sludge is to use a pump properly sized to develop sufficient head and a smooth pipe sized to produce the proper velocity without constrictions or projections and with as few bends as possible. The most important criterion for design is the ability to transfer the necessary quantity of various solids within the required time interval. In most treatment plant sludge pumping, the consistency of the sludge changes during pumping. At first, the most concentrated sludge at the bottom of the basin is pumped. After most of that sludge is removed, a more dilute sludge with characteristics ranging from semisolids to essentially liquid is pumped. The design procedure for positive-displacement pumps involves determining the maximum pumping capacity required at the minimum sludge solids concentration; determining which combinations of simplex, duplex, and triplex pumps are feasible using the capacities found for each type of pump in a manufacturer's catalog; and plotting the sludge system head curve for the maximum percentage of dry solids sludge concentration. Due to the nature of sludge, the requirements of sludge piping systems differ in many ways from those of water piping systems. The most common pipe materials for sludge piping systems are ductile iron and steel. The most common lining for ductile iron and steel pipe is cement mortar, but an even smoother lining, such as glass, is desirable. |
