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Conflict of Interest: In relation to this article, we declare that there is no conflict of interest.

Publication history: Received June 26, 2009
Accepted January 16, 2010

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Comparison of various settling velocity functions and non-Newtonian fluid models in circular secondary clarifiers

Muhammad Reza Saffarian Mohammad Hossein Hamedi Mehrzad Shams^†

Faculty of Mech. Engineering, K.N.Toosi University of Technology, Pardis St., Mola Sadra St., Vanak Sq., Tehran, Iran

shams@kntu.ac.ir

Korean Journal of Chemical Engineering, September 2010, 27(5), 1497-1508(12), 10.1007/s11814-010-0253-0

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Abstract

An axisymmetric single-phase model that predicts the sedimentation of activated sludge in a circular secondaryclarifier is developed. The k-ε turbulence model is used on a two-dimensional, orthogonal and stepwise grid. The concentration equation, which is extended to incorporate the sedimentation of activated sludge in the field of gravity, governs the mass transfer in the clarifier. The computational domain includes the sludge blanket where the viscosity is affected by the rheological behavior of the sludge. Results in case of non-Newtonian fluid model are compared with another numerical approach provided by Lakehal et al. Non-Newtonian fluid models--Bingham, Casson, and Herschel-Bulkley--are used. The influence of settling velocity functions and non-Newtonian models on the flow behavior isinvestigated. Finally, the best models are introduced and the ways that the non-Newtonian model introduces the plastic viscosity are discussed.

Keywords

Turbulence Secondary Clarifier Settling Velocity Function Activated Sludge Non-Newtonian Fluid

References

DeClercq B, Computational fluid dynamics of settling tanks: Development of experiments and rheological, settling and scraper submodels., Ph.D. Thesis, University of Ghent. (2003)
Szalai L, Krebs P, Rodi W, J. Hydraulic Eng., 120, 4 (1994)
Deininger A, Holthausen E, Wilderer PA, J. Water Res., 32, 2951 (1998)
Lakehal D, Krebs P, Krijgsman J, Rodi W, J. Hydraulic Eng., 125, 253 (1999)
McCorquodale JA, Motta EJL, Griborio A, Homes D, Georgiou I, Development of software for modeling activated sludge clarifier systems., A Technology Transfer Report, Department of Civil and Environmental Engineering, University of New Orleans, LA 70148 (2004)
Weiss M, Plosz B, Essemiani K, Meinhold J, J. Chem. Eng., 132, 1 (2007)
McCorquodale JA, Griborio A, Li J, Horneck H, Biswas N, J. Environ. Eng., 133, 263 (2007)
Chun YN, Korean J. Chem. Eng., 20(4), 670 (2003)
Lee SW, Korean J. Chem. Eng., 9(4), 199 (1992)
Choi SC, Garcia M, J. Hydraulic Eng., 128, 55 (2002)
Vradis GC, Protopapas AL, J. Hydraulic Eng., 119, 95 (1993)
Battistoni P, Treatment P, Water Sci. Tech., 36, 33 (1997)
Lotito V, Spinosa L, Mininni G, Antonacci R, Water Sci. Tech., 36, 79 (1997)
Sanin FD, Water SA., 28, 207 (2002)