Analytical and numerical description of the settling process in the activated sludge operation

Forskningsoutput: Kapitel i bok/rapport/Conference proceedingKonferenspaper i proceeding


The secondary clarifier or settler is crucial for the whole activated sludge operation. Consequently, it is important to obtain a reliable analytical model as well as a useful numerical method, which can be used in the automatic control of the settling process. Discontinuities (shocks) appear physically, and an analytical description as well as a stable numerical algorithm must be able to handle these discontinuities. A model based on the Kynch theory of sedimentation is used, where the settling flux is a function only of the local concentration and is assumed to have one inflexion point. For such non-convex flux functions, the settling process is qualitatively the same, independent of further assumptions on the shapes of the settling functions. Using the theory of nonlinear conservation laws, the main results obtained are: how to calculate transient and asymptotic behavior; how to control the concentration profile of the settler, in particular the depth of the sludge blanket, for a given load; and, a numerical algorithm which automatically preserves shocks and gives the physically correct solution according to the analytical treatment. The algorithm can be applied on any flux function (with more than one inflexion point).


Enheter & grupper

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Matematik
  • Beräkningsmatematik
  • Kemiteknik
  • Vattenteknik
  • Vattenbehandling


Titel på värdpublikationInstrumentation, control, and automation of water and wastewater treatment and transport systems : proceedings of the 5th IAWPRC Workshop held in Yokohama and Kyoto, Japan, 26 July-3 August 1990
RedaktörerR. Briggs
Antal sidor8
ISBN (tryckt)0-08-040776-5
StatusPublished - 1990
Peer review utfördJa
Evenemang5th IAWPRC Workshop - Yokohama and Kyoto, Japan
Varaktighet: 1990 jul 261990 aug 3


Konferens5th IAWPRC Workshop
OrtYokohama and Kyoto