, Volume 53, Issue 14, pp 3477–3493 | Cite as

Introducing the theory of successful settling in order to evaluate and optimize the sedimentation tanks

  • Saeid Vahidifar
  • Mohammad Reza SaffarianEmail author
  • Ebrahim Hajidavalloo


A rectangular settling tank in full scale is investigated using the Fluent software to increase its efficiency. First, the pure water is simulated in the absence of particles. Then particles are injected into the flow field and tracked by means of the discrete phase model. Three methods are presented to optimize the settling tank: (1) adding a baffle which is mounted in the bottom and is extended up to the near of free surface, (2) adding a baffle which is mounted in the free surface and is extended up to the near of the tank bottom and (3) install a bi-directional baffle which is mounted in the free surface and is extended up to the near of the bottom. These three suggestions are checked using the short-circuiting phenomenon and the successful settling theory. The successful settling theory states that a particle can be accounted as a “trapped” particle if (1) settled particle stays static and stable in the tank bottom and (2) settled particle doesn’t return to purified sewage. Although the second method provided higher efficiency, the third method was selected as the most appropriate method in order to optimize the settling tank.


Settling efficiency Re-suspension phenomenon Optimization Baffle Discrete phase model 



The authors would like to thank scientific personnel Mohammad Firoozzadeh (Mech. Eng.), operators of the company: R. Khaksari and S. Delvari for their support and insightful discussions for this study.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© Springer Nature B.V. 2018

Authors and Affiliations

  1. 1.Department of Mechanical Engineering, Faculty of EngineeringShahid Chamran University of AhvazAhvazIran

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