Simulations of reactive settling of activated sludge with a reduced biokinetic model

Research output: Contribution to journalArticle


Denitrification during the sedimentation process in secondary settlers in waste-water treatment plants has been reported to be still a significant problem. The modelling of such a process with the conservation of mass leads to a nonlinear convection–diffusion–reaction partial differential equation, which needs non-standard numerical methods to obtain reliable simulations. The purpose of this study is to provide a first extension of the Bürger–Diehl settler model, which models sedimentation without reactions, to include biological reactions. This is done with a reduced biokinetic model that contains only the relevant particulate and soluble components. Furthermore, the development is limited to batch settling. The final model describes the last settling stage of a sequencing batch reactor with denitrification. The main result of the paper is a numerical scheme that is tested for simulations with several initial conditions.


  • Raimund Bürger
  • Julio Careaga
  • Stefan Diehl
  • Camilo Mejías
  • Ingmar Nopens
  • Elena Torfs
  • Peter A. Vanrolleghem
External organisations
  • University of Concepción
  • Ghent University
  • Laval University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Computational Mathematics


  • Batch sedimentation, Degenerate parabolic PDE, Numerical scheme, Sequencing batch reactor
Original languageEnglish
Pages (from-to)216-229
Number of pages14
JournalComputers and Chemical Engineering
Publication statusPublished - 2016 Sep 2
Publication categoryResearch