Al-Qadisiyah Journal for Engineering Sciences

Numerical and experimental study of floc characteristics induced by fully baffled mixing tank agitated with retreat curved impeller

Document Type : Research Paper

Authors

Safaa Salman Ahmed 1
Adnan Abdul Ameer Abdulrasool 2
Faiq A. Hamad 3
Ayman Alak Hassn 4
Anaam K. Abdo 1
Asmaa E. Erdeiny 1

1 The State Company for Glass and Refractories, the Ministry of Industry and Minerals(MIM), Ramadi, Iraq

2 Sadar Al-Iraq University, College of Engineering, Baghdad, Iraq

3 School of Science, Engineering and Design, Teesside University, Middleborough, The UK

4 Department of Civil Engineering, College of Engineering, University of Basrah, Basrah, Iraq

10.30772/qjes.2024.148635.1191
Abstract
This study examines the impact of mixing methods in enhancing the coagulation-flocculation process. Two types of coagulants: Aluminum Sulfate Hydrate [Al2(SO4)3.16H2O] and Magnesium Chloride [MgCl2] were used. The polymer polyacrylamide (C3H5n) was utilized as a flocculent aid. A fully baffled mixing tank agitated with retreat curve impellers rotates in the range of  as an increment step and a mixing time of  was used in the present study. The present investigation includes two methodologies: the first is based on numerical solutions using MIXSIM 2.0 and ANSYS Fluent, while the second is based on experimental work. The Kaolin particles were utilized to represent the suspension collides in natural raw water. The image analysis technique was used to determine the surface area of producing flocs. The results established that the most appropriate impeller rotational speed for the flocculation process is in the range of and for alum coagulants. The maximum surface area of the floc was found to be  produced at  with  of mixing time and the maximum final floc surface area was  at  and  of mixing time. For magnesium chloride coagulant the max surface area of floc was produced at  and  of mixing time, the best impeller rotation speed was  produced the final surface area of floc which is  0.783 after  of the mixing tank. These types of floc are appropriate for the sedimentation process to be followed by the normal procedure of drinking water treatment.

Keywords

Mixing tank
Retreat impeller
Floc
Ansys
MIXSIM
Aluminum Sulfate Hydrate
Magnesium Chloride
  • Selomulya, "The Effect of Shear on Flocculation and Floc Size / Structure” Ph.D. Thesis, University of New South Wales, Australia, 2001. https://doi.org/10.26190/unsworks/20227
  • Johan, "Coagulation and Flocculation with an emphasis on water and wastewater treatment” Uplands press LTD, GRYDON CR9 ILB, England, 1980.
  • Ladislav, " Solid – liquid separation ", Butterworth – Heinemann, fourth edition, 2000.
  • L. McConnachie, "Turbulence Intensity of Mixing in Relation to Flocculation", Journal of Environmental Engineering, vol.117, No. 6, pp.731-750, November/December, 1991. https://doi.org/10.1061/(ASCE)0733-9372(1991)117:6(731)
  • J. Ducoste, M. M. Clark, R. J. Weetman" Turbulence in Flocculators: Effect of Tank Size and Impeller Type", AIChE. Journal, vol.43, No. 2, pp.328-338, February, 1997. https://doi.org/10.1002/aic.690430206
  • Wei-Ming Lu, Hong-Zhang Wu and Ming-Ying Ju, " Effect of Baffle design on the Liquid Mixing in an Aerated Stirred Tank with Standard Rushton Turbine Impeller", Pergamon, Chemical Engineering Science, vol.52, No.21:22, pp.843-3851, 1997. https://doi.org/10.1016/S0009-2509(97)88929-4
  • Bouyer, A. Line, A. Cockx and Z. DO-Quang, "Experimental Analysis of Floc Size Distribution and Hydrodynamics in a Jar-Test", Trans IChem, vol.79, part A, pp.1017-1024, November, 2001. https://doi.org/10.1205/02638760152721587
  • S. Szalai, P. Arratia, K. Johanson, F. J. Muzzio, "Mixing Analysis in a Tank Stirred with Ekato Intermig Impellers", Elsevier, Chemical Engineering Science, vol.59, pp.3793-3805, 2004. https://doi.org/10.1016/j.ces.2003.12.033
  • Rahimi, "The Effect of Impellers Layout on Mixing in a Large-Scale Crude Oil Storage Tank" Elsevier, Journal of Petroleum Science & Engineering, vol. 46, pp.161-170, 2005. https://doi.org/10.1016/j.petrol.2004.12.002
  • Ochieng, M.S. Onyango, A. Kumar, K. Kiriamiti, and P. Musonge "Mixing in a Tank Stirred by a Rushton turbine at Low Clearance", Elsevier, Chemical Engineering and Processing, vol.47, pp.842-851, 2008. https://doi.org/10.1016/j.cep.2007.01.034
  • Alok, G. Immanuel, "Effect of Different Impellers and Baffles on Aerobic Stirred Tank Ferment Using Computational Fluid Dynamics", Journal of Bioprocessing and Biotechniques, vol.4, issue 7, 2014. DOI: 10.4172/2155-9821.1000184
  • Doaa R. Hussen, Dhamyaa S. khudhur, Effect of dual impeller type on flow behavior in fully baffled mixing tank, AIP Conference Proceedings 2213, 020300(2020); https://doi.org/10.1063/5.0000149 Published Online: 25 March 2020. https://doi.org/10.1063/5.0000149
  • Pulat, E., Isman, M. K., Etemoglu, A. B., & Can, M. (2011). Effect of Turbulence Models and Near-Wall Modeling Approaches on Numerical Results in Impingement Heat Transfer. Numerical Heat Transfer, Part B: Fundamentals, 60(6), 486–519. https://doi.org/10.1080/10407790.2011.630956
  • Heck, U., Fritsching, U. and Bauckhage, K. (2001), "Fluid flow and heat transfer in gas jet quenching of a cylinder", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 11 No. 1, pp. 36-49. https://doi.org/10.1108/09615530110364079
  • AIChE Equipment testing procedure, "Mixing Equipment (Impeller Type): A Guide to Performance Evaluation ". AIChE, New York, 1987. DOI:10.1002/9780470935552
  • Pitter Wesseling "principles of computational fluid dynamics ". Springer-Verlag Berlin Heidelberg, 2001.https://doi.org/10.1007/978-3-642-05146-3
  • Bouyer and A. Line, "Experimental Analysis of Floc Size Distribution Under Different Hydrodynamics in A Mixing Tank", AIChE Journal, vol.5, No.9, pp.2064-2081, September, 2004.https://doi.org/10.1002/aic.10242
  • Ammar, Z. Driss, W. Chtourou, M. S. Abid, "Effect of The Tank Design on The Flow Pattern Generated with Pitched Blade Turbine", International Journal of Mechanics and Applications, Vol.2, No.1, pp.12-19, 2012. https://doi.org/10.1016/j.cej.2005.10.002
Al-Qadisiyah Journal for Engineering Sciences
Volume 17, Issue 3
Summer 2024
Pages 303-311

  • Receive Date 13 April 2024
  • Accept Date 04 July 2024

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