Effect of Solids Property on Rates of Solids Dislodgment
Publication: Journal of Environmental Engineering
Volume 115, Issue 1
Abstract
This study examines the rates of solids dislodgment of three synthetic solids with varying degrees of adhesive characteristics, for which a parameter characterizing the ease of solids breakoff from the surface of filter grains is proposed. This parameter is determined by a technique of curve best‐fitting onto the experimentally obtained solids profiles of the backwash water. The 50% probability values of the parameters for clay/alum, ferric chloride, and clay/polymer are 0.165, 0.120 and respectively, suggesting that the order of ease of solids breakoff is clay/alum, ferric chloride, and clay/polymer. This order is also confirmed by the experimental data of bed cleaning efficiency. Furthermore, an attempt is made to formulate a model for predicting the solids profile of backwash water and the amount of solids removal from a bed cleaning operation. The model is developed based on an assumption that the rate of solids dislodgment at a given time is proportional to the specific deposit within the filter bed at that time and its proportionality constant is primarily affected by the property of the deposited solids.
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Copyright © 1989 ASCE.
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Published online: Feb 1, 1989
Published in print: Feb 1989
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