World Environmental and Water Resources Congress 2020
Computational Fluid Dynamics Analysis for Improving Secondary Settling Tank Performance
Publication: World Environmental and Water Resources Congress 2020: Water, Wastewater, and Stormwater and Water Desalination and Reuse
ABSTRACT
The secondary settling tank (SST), also known as a secondary clarifier or secondary sedimentation tank, is a complicated and sensitive part of activated sludge process. In order to improve SST performance, computational fluid dynamics (CFD) models have been employed. In this study, a Fluent-based three-dimensional numerical model is applied to assess the capacity of the SSTs and improve their performance for the two large wastewater treatment plants (WWTPs) in southern California. Three different energy dissipating inlet (EDI) structures among the SSTs in these two WWTPs are evaluated based on the prediction of velocity profiles, sludge concentration profiles, and three different performance indicators (effluent suspended solids, recycle solids concentration, and sludge blanket height) over a range of loading rates. The results show that (1) the Orie Albertson EDI outperforms the original tangential EDI under the normal flow conditions but is inferior to the tangential EDI at high flow conditions; (2) the LA-EDI performance can be improved by optimizing the depth of the flocculating well; (3) SSTs are more sensitive to the increase of MLSS concentration than the increase of flow rate; (4) an alternative indicator needs to be developed to differentiate the SST’s performance under the extreme SLR.
Get full access to this article
View all available purchase options and get full access to this chapter.
REFERENCES
Armbruster, M., Krebs, P., Rodi, W. 2001. Numerical modeling of dynamic sludge blanket behavior in secondary clarifiers. Wat Sci Technol. 43, (11)173-180.
Burt, D.J. 2010. Improved Design of Settling Tanks Using an Extended Drift Flux Model. Ph.D. thesis, University of Bristol, UK.
Dahl, C., Larsen, T., Petersen, O. 1994. Numerical modeling and measurement in a test secondary settling tank. Wat Sci Technol. 30, (2)219-228.
Das, S., Bai, H., Wu, C., Kao, J.-H., Barney, B., Kidd, M. and Kuettel, M. 2016. Improving the performance of industrial clarifiers using three-dimensional computational fluid dynamics. Eng. Appl. Comp. Fluid. 10, (1)130-144.
De Clercq, B. 2003. Computational fluid dynamics of settling tanks: development of experiments and rheological, settling, and scraper submodel. PhD Thesis, Ghent University, Belgium.
Ekama, G.A., Marais, P. 2004. Assessing the applicability of the ID flux theory to full-scale secondary settling tank design with a 2D hydrodynamic model. Water Res. 38, (3)495-506.
Gao, H., Stenstrom, M. K. 2017. Computational fluid dynamics applied to secondary clarifier analysis. In proceeding. World Environmental and Water Resources Congress 2017: Water, Wastewater, and Stormwater; Urban Watershed Management; and Municipal Water Infrastructure (pp. 301–315). Sacramento, CA: ASCE. https://doi.org/10.1061/9780784480632
Gao, H., and Stenstrom, M. K. 2018a. Evaluation of three turbulence models in predicting of the hydrodynamics of a secondary sedimentation tank. Water Res, 143, 445–456.
Gao, H., and Stenstrom, M. K. 2018b. Turbulence and interphase mass diffusion assumptions on the performance of secondary settling tanks. Wat Environ Res. 91, 1-10.
Gao, H., and Stenstrom, M. K. 2019a. Generalizing the effects of the baffling structures on the buoyancy-induced turbulence in secondary settling tanks with eleven different geometries using CFD models. Chem Eng Res Des. 143, 215-225.
Gao, H. and Stenstrom, M. K. 2019b. Evaluating the effects of inlet geometry on the limiting flux of secondary settling tanks with CFD model and 1D flux theory model. J. Environ. Eng- Special Collection on CFD. 2019, 145(10), 04019065-1-9.
Gao, H. and Stenstrom, M. K. 2019c. The influence of wind in secondary settling tanks for wastewater treatment- A computational fluid dynamics study. Part I: circular secondary settling tanks. Water Environ Res. (Accept). https://doi.org/10.1002/wer.1241.
Gao, H. and Stenstrom, M. K. 2019d. The influence of wind in secondary settling tanks for wastewater treatment- A computational fluid dynamics study. Part II: rectangular secondary settling tanks. Water Environ Res. (Accept). https://doi.org/10.1002/wer.1244.
Gao, H and Stenstrom, M. K. 2019e. Uncertainty analysis of the model parameters and inlet turbulence boundary specification methods of secondary settling tank. J. Environ. Eng. (Accept).
Gerges, H., McCorquodale, J. A. 2008. Thirty Years of Sedimentation Tanks Modeling Learning from Experience. Proceedings of the 80th Annual Water Environment Federation Technical Exposition and Conference [CD-ROM]; Chicago, IL, Oct 18–22; Water Environment Federation: Alexandria, Virginia.
Gong, M., Xanthos, S., Ramalingam, K., Fillos, J., Beckmann, K., Deur, A., McCorquodale, J. A. 2011. Development of a flocculation sub-model for a 3-D CFD model based on rectangular settling tanks. Wat Sci Technol. 63, (2)213-219.
Jayanti, S., Narayanan, S. 2004. Computational study of particle-eddy interaction in sedimentation tanks. J. Environ. Eng. 130, (1)37-49.
Krebs, P. 1991. The hydraulic of final settling tanks. Wat Sci Technol. 23, 1037-1046.
Krebs, P., Vischer, D., Gujer, W. 1992. Improvement of secondary clarifiers efficiency by porous wall. Wat Sci Technol. 26(5-6), 1147-1156.
Krebs, P., Vischer, D., Gujer, W. 1995. Inlet-structure design for final clarifiers. J. Environ. Eng. 121, (8)558-564.
Lakehal, D., Krebs, P., Krijgsman, J., Rodi, W. 1999. Computing shear flow and sludge blanket in secondary clarifiers. J. Hydraul. Eng. 125, (3)253-262.
Matko, T., Fawcett, N., Sharp, A., Stephenson, T. 1997. Recent progress in the numerical modelling of wastewater sedimentation tanks. Process Saf Environ. 74, 245-258.
McCorquodale, J. A., La Motta, E. J., Griborio, A., Homes, D., Georgiou, I. 2004. 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.
Parker, D.S. 1983. Assessment of Secondary Clarification Design Concepts. J. Water Pollut Control Fed. 55, (4)349-359.
Patziger, M., Kainz, H., Hunze, M., Józsa, J. 2012. Influence of secondary settling tank performance on suspended solids mass balance in activated sludge systems. Water Res. 46, (7)2415-2424
Ramalingam, K., Fillos, J., Xanthos, S., Gong, M., Deur, A., Beckmann, K. 2009. Development and Validation of a 3-Dimensional Computational Fluid Dynamics (CFD) Model for Rectangular Settling Tanks in New York City Water Pollution Control Plants. Water Pract Tech. 4, (1)1-9.
Ramalingam, K., Xanthos, S., Gong, M., Fillos, J., Beckmann, K., Deur, A., McCorquodale, J. A. 2012. Critical modeling parameters identified for 3D CFD modeling of rectangular final settling tanks for New York City wastewater treatment plants. Wat Sci Technol. 65, (6)1087-1094.
Ramin, E., Wagner, D.S., Yde, L., Binning, P.J., Rasmussen, M.R., Mikkelsen, P.S., Plósz, B.G. 2014. A new settling velocity model to describe secondary sedimentation. Water Res. 66, 447-458.
Samstag, R., Zhou, S., Chan, R., Royer, C., Brown, K. 2010. Comprehensive Evaluation of Secondary Sedimentation Performance. Proceedings of the Water Environment Federation 82nd Annual Technical Conference and Exposition, New Orleans, LA.
Stamou, A. I., Theodoridis, G., Xanthopoulos, K. 2009. Design of secondary settling tanks using a CFD model. J. Environ Eng. 135, (7)551-561.
Vitasovic, Z. C., Zhou, S., McCorquodale, J. A., Lingren, K. 1997. Secondary clarifier analysis using data from the Clarifier Research Technical Committee protocol. Wat Environ Res. 69, (5)999-1007.
Wahlberg, E. J., Gerges, H. Z., Gharagozian, A., Stenstrom, M. K. 1998. Of: Secondary clarifier analysis using data from the clarifier research technical committee protocol. Wat Environ Res. 70, (2)249-253.
Wang, X., Yang, L., Sun, Y., Song, L., Zhang, M., Cao, Y. 2008. Three-dimensional simulation on the water flow field and suspended solids concentration in the rectangular sedimentation tank. J. Environ. Eng. 134, (11)902-911.
Wang, X., Zhou, S., Li, T., Zhang, Z., Sun, Y., Cao, Y. 2011. Three-dimensional simulation of the water flow field and the suspended-solids concentration in a circular sedimentation tank. Can. J. Civ. Eng. 38, (7)825-836.
Wicklein, E., Samstag, R.W. 2014. Optimization of rectangular secondary sedimentation basins using computational fluid dynamic (CFD) modeling. In: Proceedings of WEFTEC 87th Annual WEF Technical Exhibition and Conference, New Orleans, LA, USA.
Xanthos, S., Gong, M., Ramalingam, K., Fillos, J., Deur, A., Beckmann, K., McCorquodale, J. A. 2011. Performance assessment of secondary settling tanks using CFD modeling. Water Resour Manag. 25, (4)1169-1182
Xanthos, S., Ramalingam, K., Lipke, S., McKenna, B., Fillos, J. 2013. Implementation of CFD modeling in the performance assessment and optimization of secondary clarifiers: the PVSC case study. Wat Sci Technol. 68, (9)1901-1913.
Zhou, S., McCorquodale, J. A., Vitasovic, Z. 1992. Influences of density on circular clarifiers with baffle. J. Environ. Eng. 118, (6)829-847.
Zhou, S., Mak, B. W., Leong, E., Hon Shing, K., Shukuen, I., Tze Kwan, L. 2010. Optimized centre feed clarifier design for the Tai Po Sewage Treatment Works, Hong Kong. Water Environ J. 24, (2)140-14
Information & Authors
Information
Published In
World Environmental and Water Resources Congress 2020: Water, Wastewater, and Stormwater and Water Desalination and Reuse
Pages: 212 - 224
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
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.