Quantifying the sources of uncertainty when calculating the limiting flux in secondary settling tanks using iCFD

Estelle Guyonvarch, Elham Ramin, Murat Kulahci, Benedek G. Plósz

Research output: Contribution to journalArticlepeer-review

3 Citations (SciVal)


Solids-flux theory (SFT) and state-point analysis (SPA) are used for the design, operation and control of secondary settling tanks (SSTs). The objectives of this study were to assess uncertainties, propagating from flow and solids loading boundary conditions as well as compression settling behaviour to the calculation of the limiting flux (JL) and the limiting solids concentration (XL). The interpreted computational fluid dynamics (iCFD) simulation model was used to predict one-dimensional local concentrations and limiting solids fluxes as a function of loading and design boundary conditions. A two-level fractional factorial design of experiments was used to infer the relative significance of factors unaccounted for in conventional SPA. To move away from using semi-arbitrary safety factors, a systematic approach was proposed to calculate the maximum SST capacity by employing a factor of 23% and a regression meta-model to correct values of JL and XL, respectively - critical for abating hydraulic effects under wet-weather flow conditions.

Original languageEnglish
Pages (from-to)241-252
Number of pages12
JournalWater Science and Technology
Issue number2
Early online date28 Feb 2020
Publication statusPublished - 24 Apr 2020


  • Computational fluid dynamics
  • Interpreted computational fluid dynamics model (iCFD)
  • One-dimensional advection dispersion model
  • Secondary settling tank
  • Solids-flux theory
  • Statistical factor screening

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology


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