World Environmental and Water Resources Congress 2020
Development of a Computational Fluid Dynamics (CFD) Model of a Full-Scale Oxidation Ditch Incorporating Activated Sludge Model (ASM)-1
Publication: World Environmental and Water Resources Congress 2020: Water, Wastewater, and Stormwater and Water Desalination and Reuse
ABSTRACT
Wastewater treatment facilities combine biological, physical, and chemical unit processes to remove pollutants and restore wastewater to a quality that is harmless. This work develops a water-sludge multiphase computational fluid dynamics (CFD) model of a full-scale oxidation ditch, a biological unit process that couples hydrodynamics with a bio-kinetics model, namely the activated sludge model (ASM)-1, to analyze the spatial and temporal distribution of the ASM-1 components. This model represents one of the oxidation ditches at the Valrico Advanced Wastewater Treatment Facility in Dover, Florida. The ditch is oval-shaped and equipped with two vertical axis surface mechanical aerators, one in either curved end of the ditch. The motion of the aerators was simulated with the multiple reference frame approach. Turbulence was accounted for via the standard k-epsilon model with standard wall functions. ASM-1 consists of 12 components and 8 kinetic processes that describe carbon oxidation, nitrification, and denitrification. Each component of ASM-1 was incorporated into the CFD model via Reynolds-averaged scalar advection-diffusion-reaction transport equations. The model was ran in single and multiphase modes, where in single phase mode the hydrodynamics account for water only and in the multiphase mode the hydrodynamics account for both water and sludge phases. It is found that the vertical stratification induced by the sludge phase can impact the dissolved oxygen distribution in the ditch and thus ASM components such as active heterotrophic biomass and particulate products from biomass decay.
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6. ACKNOWLEDGEMENTS
K. Pierre acknowledges the Florida Education Fund - McKnight Doctoral Fellowship, the Alfred P. Sloan Foundation, NSF PIRE (Grant #: 1243510) and AAUW - American Fellowship for financial support. The authors acknowledge the Hillsborough County Public Utilities for partially supporting this work.
7. REFERENCES
ANSYS Corporation. (2013). ANSYS Fluent Theory Guide. Release 15.0. Canonsburg, PA.
Climent, J., Basiero, L., Martinez-Cuenca, R., Berlanga, J. G., Julian-Lopez, B. and Chiva, S. (2018). “Biological reactor retrofitting using CFD-ASM modelling.” Chemical Engineering Journal, 348, 1 – 14.
Fan, L., Xu, N., Wang, Z. and Shi, H. (2010). “PDA experiments and CFD simulation of a lab-scale oxidation ditch with surface aerators.” Chemical Engineering Research and Design, 88, 23 – 33.
Henze, M., Gujer, W., Mino, T. and van Loosdrecht, M. (2000). “Activated sludge models: ASM1, ASM2, ASM2d and ASM3. Scientific and Technical Report 9.” IWA Task Group on Mathematical Modeling for Design and Operation of Biological Wastewater Treatment. IWA Publishing, London.
Lakehal, D., Krebs, P., Krijgsman, J. and Rodi, W. (1999). “Computing shear flow and sludge blanket in Secondary Clarifiers.” Journal of Hydraulic Engineering, 125(3), 253-262.
Lei, L. and Ni, J. (2014). “Three-dimensional three-phase model for simulation of hydrodynamics, oxygen mass transfer, carbon oxidation, nitrification and denitrification in an oxidation ditch.” Water Research, 53, 200 – 214.
Le Moullec, Y., Potier, O., Gentric, C. and Leclerc, J. P. (2008). “Flow field and residence time distribution simulation of a cross flow gas-liquid wastewater treatment reactor using CFD.” Chemical Engineering Science, 63, 2436 – 2449.
LeMoullec, Y., Gentric, C., Potier, O. and Leclerc, J. P. (2010). “CFD simulation of the hydrodynamics and reactions in an activated sludge channel reactor of wastewater treatment.” Chemical Engineering Science, 65, 492 – 498.
Rehman, U. (2016). “Next Generation Bioreactor Models for Wastewater Treatment Systems by Means of Detailed Combined Modelling of Mixing and Biokinetics.” Ghent University, Belgium.
Stamou, A. I. (1997). “Modelling of oxidation ditches using an open channel flow 1-D advection-dispersion equation and ASM-1 Process Description.” Water Science and Technology, 36(5), 269 – 276.
Tchobanoglous, G., Burton, F., Stensel, H. and Metcalf & Eddy. (2003). Wastewater Engineering: Treatment and Reuse, McGraw-Hill, Boston.
Wicklein, E. and Samstag, R. (2009). “Comparing commercial and transport CFD models for secondary sedimentation.” WEFTEC 2009, Water Environment Federation, Orlando, Florida, U.S.A, Session 81 – 90, 6066-6081.
Wilcox, D. C. (1994). Turbulence Modeling for CFD. DCW Industries, La Cañada Flintridge, California.
World Health Organization (WHO). (2017). “Sanitation.” <https://www.who.int/news-room/fact-sheets/detail/sanitation> (November 14, 2019).
Zhang, J., Pierre, K., and Tejada-Martínez, A. E. (2019). “The impacts of flow and tracer release unsteadiness on tracer analysis of water and wastewater treatment facilities.” Journal of Hydraulic Engineering, 145(4).
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World Environmental and Water Resources Congress 2020: Water, Wastewater, and Stormwater and Water Desalination and Reuse
Pages: 225 - 236
Editors: Sajjad Ahmad, Ph.D., and Regan Murray, Ph.D.
ISBN (Online): 978-0-7844-8298-8
Copyright
© 2020 American Society of Civil Engineers.
History
Published online: May 14, 2020
Published in print: May 14, 2020
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