Effects of Scale and Discharge Variation on Similitude and Solute Transport in Water Treatment Tanks
Publication: Journal of Environmental Engineering
Volume 140, Issue 1
Abstract
This paper addresses the design and experimentation aspects of scaled contact tanks, a key type of treatment units in water works worldwide. The paper covers the effects of scale and discharge variation on the dynamic similitude and hydraulic efficiency of such tanks. The flow patterns tending to complete mixing (CM) and plug flow (PF) were studied, each assessed in a prototype and three further geometrically similar models of L-shaped and serpentine geometries. Tracer experiments were conducted under five discharge values. The sensitivity of each flow pattern to the changing conditions was assessed based on the residence time distribution curves and hydraulic efficiency index values, contrasted for prototypes and their scaled models. Although the CM flow pattern was insensitive to the variation of scale and discharge, within the ranges tested in this study, the PF pattern was affected by both variations when the flow regime was not turbulent in a model tank. A dependency of the dispersion number on the Reynolds number was observed, leading to the proposal of a new model to support the design and upscaling of results in contact tank studies.
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Acknowledgments
We thank the anonymous reviewers for their suggestions to improve the manuscript and acknowledge the support of the Postgraduate Programme in Environmental Engineering of Federal University of Espirito Santo (PPGEA/UFES, Brazil) and a scholarship provided by the Brazilian National Council for Research and Development (CNPq).
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Information & Authors
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Published In
Journal of Environmental Engineering
Volume 140 • Issue 1 • January 2014
Pages: 30 - 39
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Aug 30, 2012
Accepted: Aug 12, 2013
Published online: Aug 14, 2013
Published in print: Jan 1, 2014
Discussion open until: Jan 14, 2014
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