Air Dynamics Through Filter Media During Air Scour
Publication: Journal of Environmental Engineering
Volume 110, Issue 3
Abstract
The dynamics of air motion through filter media under conditions of air scour alone, simultaneous air and subfluidization water flow and simultaneous air and fluidization water flow were studied. Particular combinations of simultaneous air and subfluidization water flows cause the formation and collapse of air pockets within the bed: termed Collapse‐Pulsing. This condition probably created significant abrasion between the filter media grains because the intensity of abrasion is related to the effective stresses between the grains and the magnitude of their relative movement. It is rationalized that collapsepulsing is the probable optimum condition for air scour. Three sands of effective sizes, 0.46 mm, 0.64 mm, and 0.88 mm, were experimentally studied and a simple empirical predictive equation for collapse‐pulsing was established. The equation is also shown to be valid for predicting the condition for a minimum loss of media during backwash. The equation could be used for the design of air scour systems to calculate the required simultaneous air and subfluidization water flows for graded sands.
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References
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Information & Authors
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Published In
Journal of Environmental Engineering
Volume 110 • Issue 3 • June 1984
Pages: 591 - 606
Copyright
Copyright © 1984 ASCE.
History
Published online: Jun 1, 1984
Published in print: Jun 1984
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