A Perforated Baffle Design to Improve Mixing in Contact Tanks

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Nasyrlayev N., Kizilaslan M. A., Kurumus A. T., DEMİREL E., Aral M. M.

WATER, vol.12, no.4, 2020 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 12 Issue: 4
  • Publication Date: 2020
  • Doi Number: 10.3390/w12041022
  • Journal Name: WATER
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Agricultural & Environmental Science Database, Aqualine, Aquatic Science & Fisheries Abstracts (ASFA), CAB Abstracts, Compendex, Environment Index, Geobase, INSPEC, Pollution Abstracts, Veterinary Science Database, Directory of Open Access Journals
  • Keywords: water treatment, contact tank, computational fluid dynamics (CFD), hydraulic and mixing efficiencies, perforated baffle, PERFORMANCE
  • Çanakkale Onsekiz Mart University Affiliated: No


In this study, a perforated baffle design is proposed to improve mixing in contact tanks. Turbulent flow through the perforated baffle is studied at the perforation hole scale. The contribution of jets emerging from the perforations to the mixing process is evaluated in terms of standard mixing indexes for various perforation parameters, such as the solidity ratio and hole diameter. Based on numerical simulation results, the two sets of perforated baffles that yielded the highest performance were manufactured from polycarbonate and tracer studies were conducted on a laboratory model. Comparison of numerical and experimental results demonstrates that the numerical model developed is reliable in simulating the flow through the perforated baffles and the associated mixing level in the contact tank. Numerical simulations indicate that the jet flow structure through the perforated baffle penetrates to the recirculation zones in the neighboring chambers and turns the dead zones into active mixing zones. Furthermore, large scale turbulent eddies shed by the perforations contribute to the mixing process in the chambers of the tank. With the use of the perforated baffle design, it is shown that the hydraulic efficiency of the tank can be improved from average to superior according to the baffling factor, and the associated mixing in the proposed design can be improved by 31% according to the Morrill index.