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A consistent modelling methodology for secondary settling tanks: A reliable numerical method.

På svenska

Author

  • Raimund Bürger
  • Stefan Diehl
  • Sebastian Farås
  • Ingmar Nopens
  • Elena Torfs

Summary, in English

The consistent modelling methodology for secondary settling tanks (SSTs) leads to a partial differential equation (PDE) of nonlinear convection–diffusion type as a one-dimensional model for the solids concentration as a function of depth and time. This PDE includes a flux that depends discontinuously on spatial position modelling hindered settling and bulk flows, a singular source term describing the feed mechanism, a degenerating term accounting for sediment compressibility, and a dispersion term for turbulence. In addition, the solution itself is discontinuous. A consistent, reliable and robust numerical method that properly handles these difficulties is presented. Many constitutive relations for hindered settling, compression and dispersion can be used within the model, allowing the user to switch on and off effects of interest depending on the modelling goal as well as investigate the suitability of certain constitutive expressions. Simulations show the effect of the dispersion term on effluent suspended solids and total sludge mass in the SST. The focus is on correct implementation whereas calibration and validation are not pursued.

Department/s

Publishing year

2013

Language

English

Pages

192-208

Publication/Series

Water Science and Technology

Volume

68

Issue

1

Document type

Journal article

Publisher

IWA Publishing

Topic

  • Computational Mathematics
  • Mathematics
  • Chemical Engineering
  • Water Engineering
  • Water Treatment

Keywords

  • continuous sedimentation
  • partial differential equation
  • secondary clarifier
  • simulation model
  • wastewater treatment

Status

Published

Research group

  • Partial differential equations
  • Numerical Analysis

ISBN/ISSN/Other

  • ISSN: 0273-1223