Water Mixing and Renewal in Circular Cross-Section Storage Tanks as Influenced by Configuration and Operational Conditions
Publication: Journal of Hydraulic Engineering
Volume 147, Issue 12
Abstract
Storage tanks are essential components of water supply systems to store water to face normal and emergency conditions and to level off required pressures. However, tanks can also be the source of water quality deterioration due to poor mixing and long residence times. In this paper, the effect of the tank configuration and of the operating mode on water mixing and renewal in cylindrical small-scale tanks of typical configurations is assessed. Results show that nearly complete mixing conditions can be attained in the tanks with inlet and outlet pipes located at opposite walls. Short-circuiting and the formation of dead zones is demonstrated in tanks with inlet and outlet pipes located close together. In fill-and-draw mode, water mixing is enhanced by a wide water-level variation, but renewal takes longer than in steady-state conditions. In addition, an empirical formula is proposed for estimating the turnover time in cylindrical tanks operated at a constant level. By identifying the configurations and operating conditions that promote mixing, this paper contributes to better water quality management in existing and new storage tanks in distribution systems.
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Data Availability Statement
All data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.
Acknowledgments
The authors would like to thank the Fundação para a Ciência e Tecnologia (FCT) for funding the Project PTDC/ECI-EGC/32102/2017 (IMIST–Improving Mixing in Storage Tanks for safer water supply) and the H2DOC doctoral program for the PhD grant PD/BD/135214/2017. The authors also thank Dr. José Menaia for his valuable comments.
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Published In
Journal of Hydraulic Engineering
Volume 147 • Issue 12 • December 2021
Copyright
© 2021 American Society of Civil Engineers.
History
Received: Feb 21, 2021
Accepted: Aug 24, 2021
Published online: Oct 13, 2021
Published in print: Dec 1, 2021
Discussion open until: Mar 13, 2022
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