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Flow in a packed bed of particles is described by the Ergun equation: LP=150d23(1)2u+1.75d3(1)u2 Discuss briefly the form of the equation and the significance of the terms. A settling tank in a wastewater treatment plant consists of an open cylindrical vessel 10m in diameter and 4m in height, which contains at its base a supported bed of spherical particles 1m in depth. Under normal operating conditions a steady downflow through the particle bed is sustained by maintaining a liquid layer above the bed surface. The water exits to atmosphere at the base of the system. The detailed characteristics of the particles are unknown, however, experimental tests yield the following data on H, the thickness of the liquid layer, at two values of Q, the liquid feed rate: Based upon the above data, estimate the maximum and minimum liquid flowrates which should be used in the system in order to sustain its operation. Note - You may assume the packing particles to be spherical