Two-Dimensional LDV Measurement, Modeling, and Optimal Design of Rectangular Primary Settling Tanks
Publication: Journal of Environmental Engineering
Volume 136, Issue 5
Abstract
To optimize the design parameters of rectangular primary settling tanks, we used two-dimensional laser Doppler velocimetry (2D LDV) to conduct flow field measurements in five cases and used a previous model to simulate the flow field. The relative baffle submergence height and the ratio of tank length to height were optimized in a low suspended solid (LSS) concentration . The experimental and simulation results show that a large recirculation zone exists behind the reaction baffle and the flow magnitude is small in the recirculation region; the length of recirculation increases with an increasing flow rate; the length of recirculation increases as the depth of the submerged reaction baffle increases; and the variation of the reaction baffle height can affect the flow field more significantly than does the variation of the flow rate. We also determined that to reach a higher removal rate and to optimize the area dimensions of a sedimentation tank, a length-to-height design ratio between 8 and 12 is optimal.
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Acknowledgments
This project was partially supported by the 973 Program (Grant No. UNSPECIFIED2007CB714105), the National Project of Scientific and Technical Supporting Programs (Grant No. UNSPECIFIED2007BAC18B01), and the National Natural Science Foundation of China (Grant No. NNSFC50679049). This research was supported by the State Key Laboratory of Urban Water Resource and Environment (Grant No. UNSPECIFIED08UWQA04). Our thanks to Professor Pengzhi Lin (State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University) for providing the experimental laboratory and to Pin Liu, Wenmin Yi, and Yanhua Wu for providing much assistance in this experiment.
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Information & Authors
Information
Published In
Journal of Environmental Engineering
Volume 136 • Issue 5 • May 2010
Pages: 501 - 507
Copyright
© 2010 ASCE.
History
Received: Aug 1, 2008
Accepted: Oct 23, 2009
Published online: Oct 31, 2009
Published in print: May 2010
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