An Efficient Contact Tank Design for Potable Water Treatment

Abstract

Bu çalışmada bir temas tankının içindeki türbülanslı akış ile arıtıcı konsantrasyonunun hareketinin üç boyutlu sayısal benzetimi ikinci mertebeden yakınsak bir hesaplama modeli kullanılarak gerçekleştirilmiştir. Arıtıcının zamanla değişen akım ile karışımı Large Eddy Simulation (LES) türbülans yaklaşımı kullanılarak modellenmiştir. Temas tankının girişinden enjekte edilen arıtıcı konsantrasyonunun tankın çıkışındaki dağılımını gösteren Kalma Süresi Dağılımı (KSD) ve toplam KSD eğrileri kullanılarak temas tankının hidrolik ve karışım verimlerine ait endeksler belirlenmiştir.  Tank içindeki şaşırtma perdeleri üzerinde yapılan değişiklik ile temas sisteminin verimi arttırılarak enerji sarfiyatlarının azaltılabileceği gösterilmiştir. Önerilen yeni perde tasarımı sayesinde temas tankının hidrolik verimi %44, karışım verimi ise %42 oranında arttırılmış, suyun iletilmesi için gereken enerji sarfiyatı ise %43 oranında azaltılmıştır. 

Keywords

• Temas tankı,içme suyu arıtma,HAD,türbülans

An Efficient Contact Tank Design for Potable Water Treatment

Abstract

In this study, a second order accurate Large Eddy Simulation (LES) model is used to simulate three-dimensional turbulent flow and disinfectant transport in a contact tank. The hydraulic and mixing indexes of the tank are evaluated based on computational tracer studies. It is shown that the energy consumption rates of the contact tank can be reduced by the use of the proposed slot-baffle design instead of the conventional baffle system that is used in these facilities. The proposed slot-baffle design improves the hydraulic efficiency by 44%, mixing efficiency by 42% and reduces the energy required to drive the flow through the system by 43%. The outcome reported in this study shows that the energy consumption in water treatment plants can be significantly reduced when the novel baffle design is implemented on existing contact tanks without expensive infrastructure modifications. 

 

Keywords

• Contact tank,treatment of potable water,CFD,turbulence,LES

References

1. Çakmakçı, M., Özkaya, B., Yetilmezsoy, K. Ve Demir, S. Su Arıtma Tesislerinin Tasarım ve İşletme Esasları, İstanbul, 2013.
2. Zhang, J., Martinez, A. E. T. and Zhang, Q., Hydraulic Efficiency in RANS of the Flow in Multi-chambered Contactors, Journal of Hydraulic Engineering, 139, 1150-1157, 2013.
3. Angeloudis, A., Stoesser, T., Falconer, R.A. and Kim,D.J., Flow, Transport and Disinfection Performance in Small –and Full-Scale Contact Tanks, Journal of Hydro-Environment Research, 9, 15-27, 2015.
4. Rauen, W.B., Lin, B., Falconer, R.A. and Teixeira, E.C., CFD and Experimental Model Studies for Water Disinfection Tanks with Low Reynolds Number Flows, Chemical Engineering Journal, 137, 550-600, 2008.
5. Angeloudis, A., Stoesser, T., and Falconer, R.A., Predicting the Disnfection Efficiency Range in Chlorine Contact Tanks Through a CFD-Based Approach, Water Research, 60, 118-129, 2014.
6. Kim, D., Kim, D.I., Kim, J.H., and Stoesser, T., Large Eddy Simulation of Flow and Tracer Trasnport in Multichamber Ozone Contactors, Journal of Environmental Engineering, 136, 1, 22-31, 2010.
7. Wols, B.A., Hofman, J.A.M.H., Uijttewaal, W.S.J., Rietveld, L.C. and Dijk, J.C., Evaluation of Different Disinfection Calculation Methods using CFD, Environmental Modelling & Software, 25, 573-582, 2010.
8. Zhang, J., Martinez, A.E.T., Lei, H. and Zhang, Q., Indicators for Technological, Environmental and Economic Sustainablity of Ozone Contactors, Water Research, 101, 606-616, 2016.

9. Zhang, J., Martinez, A.E.T., and Zhang, Q., Evaluation of Large Eddy Simulation and RANS for Determining Hydraulic Performance of Disinfection Systems for Water Treatment, Journal of Fluids Engineering, 136, 121102-121102-9, 2014.
10. Kim, D., Elovitz, M., Roberts, P.J.W. and Kim, J.H., Using 3D LIF to Investigate and Improve Performance of a Multichamber Ozone Contactor, Americal Water Works Association Journal, 102, 61-70, 2010.
11. Zhang, Y., Street, R.L. and Koseff, J.R., A Dynamic Mixed Subgrid-Scale Model and Its Application to Turbulent Recirculating Flows, Physics of Fluids, 5, 3186-3196, 1993.
12. OpenFOAM, The OpenFOAM Foundation; OpenCFD Ltd.: Bracknell, UK, 2015.
13. Demirel, E. and Aral, M.M., Unified Analysis of Multi-chamber Contact Tanks and Mixing Efficiency Based on Vorticity Field. Part I: Hydrodynamic Analysis, Water, 8, 495-505, 2016.
14. U.S. EPA. , Disinfection Profiling and Benchmarking Guidance Manual, Appendix A. Rep. No. EPA-815-R-99-013, 1999, U.S. EPA, Washington, D.C
15. Demirel, E. and Aral, M.M., Unified Analysis of Multi-Chamber Contact Tanks and Mixing Efficiency Based on Vorticity Field. Part II: Transport Analysis, Water, 8, 537-554, 2016.
16. Elliot, T., Zeier, B., Xagoraraki, I. and Harrington, G. W., Energy Use at Wisconsin’s Drinking Water Facilities, Rep. 2003, 222-1, Energy Center of Wisconsin, Madison, WI.
17. Aral, M.M. and Demirel, E., Novel Slot-Baffle Design to Improve Mixing Efficiency and Reduce Cost of Disinfection in Drinking Water Treatment, Journal of Environmental Engineering ASCE, Artilce in Press.
18. Aral, M.M. and Demirel, E., A New Baffle Design to Improve Mixing and Reduce the Flow Through Energy Requirements in Chlorine and Ozone Contact Tanks, Patent # 62/498,260, 10 January 2017.
19. Angeloudis, A., Stoesser, T., Gualtieri, C. and Falconer, R.A., Contact Tanks Design Impact on Process performance, Environ. Model. Assess., 21, 563-576, 2016.