A Simplified Control-Oriented Model of the Activated Sludge Process

Research output: Contribution to journalArticle


Automatic control systems rely on models to predict the near future and identification algorithms to adapt the models to changing process behaviour. The traditionally highly complex models of the activated sludge process developed for scientific purposes cannot be identified from on-line measurements and are not suited for process control purposes in their present form. Model decoupling based on the different time scales of the dynamic processes is one possible way of attacking this problem. It allows the implementation of more simple and realistically applicable controllers in combination with predictions based on simplified models in hierarchical control structure. This paper discusses these concepts and presents a reduced order model describing carbonaceous removal, nitrification, and denitrification in a medium time scale (several hours/days). The model parameters are identifiable from available on-line measurements and the dynamic behaviour is verified against computer simulations of the IAWQ activated sludge model no. 1.


Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Other Electrical Engineering, Electronic Engineering, Information Engineering


  • activated sludge, automatic control, dynamic modelling, model complexity, model identification, model reduction, wastewater treament
Original languageEnglish
Pages (from-to)3-16
JournalMathematical and Computer Modelling of Dynamical Systems
Issue number1
Publication statusPublished - 1995
Publication categoryResearch