Air Flow in Sanitary Sewer Laterals
Publication: Journal of Hydraulic Engineering
Volume 150, Issue 4
Abstract
Air in the headspace of sewer laterals can be driven by the flowing sewage as well as air pressure. In this study, the openings on manholes for air flow are approximated as a thin continuous slot at the laterals. In this way, the governing equations can be solved analytically for infinitely long laterals without water flow. For cases with water flow, a numerical solution is developed. It is found that the air flow pattern in a long lateral can be categorized into three zones. The zone closest to the trunk is defined as the “zone of influence,” where the air flow in the lateral is dominated by air pressure, and the air pressure and air velocity decay exponentially in the lateral. The second zone is named as “zone of equilibrium” where the air pressure gradient is zero and the air flow is only driven by the drag of water and can be calculated analytically. The air flow zone farthest from the trunk is defined as the “zone of induction” where the air is inducted into the system for mass balance in the system. An explicit fitting expression on the air velocity and water velocity in a long lateral is provided. A graphic solution for air velocity and zone of influence is also developed for a quick estimation on the air movement in sewer laterals.
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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 acknowledge the financial support of National Key R&D Program of China (Grant No. 2022YFC3203200), the Natural Sciences and Engineering Research Council of Canada, EPCOR Inc., and the Natural Science Foundation of Zhejiang province, China (Grant No. LQ23E090004).
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Published In
Journal of Hydraulic Engineering
Volume 150 • Issue 4 • July 2024
Copyright
© 2024 American Society of Civil Engineers.
History
Received: Jul 23, 2023
Accepted: Feb 13, 2024
Published online: May 2, 2024
Published in print: Jul 1, 2024
Discussion open until: Oct 2, 2024
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