Integration of performance, molecular biology and modeling to describe the activated sludge process

V. Urbain, B. Mobarry, V. De Silva, D. A. Stahl, B. E. Rittmann, J. Manem

Research output: Contribution to journalConference articlepeer-review

55 Scopus citations


To study process performance and population dynamics in activated sludge, a pilot-scale Membrane Bioreactor (MBR) was installed in a municipal wastewater treatment plant (Aubergenville, France). Since no solids losses occur in the MBR effluent, the sludge residence time (SRT) can be: i) easily controlled by means of the sludge withdrawal, and ii) dissociated from the hydraulic residence time (HRT). A complete characterization of this activated sludge system was performed at three sludge ages (5, 10 and 20 days). Raw and treated wastewater quality, as well as sludge concentration, was analyzed, nucleic probe analysis was performed to determine the heterotrophic and nitrifier populations, and the results were compared to the output from a multispecies model that integrates substrate removal kinetics and soluble microbial products (SMP) production/consumption. This paper presents an integrated analysis of the activated sludge process based on chemical, molecular biology, and mathematical tools. The model was able to describe the MBR system with a high degree of accuracy, in terms of COD removal and nitrification, as well as sludge production and population dynamics through the ratio of active nitrifiers/bacteria. Both steady-state and transient conditions could be described accurately by the model, except for technical problems or sudden variations in the wastewater composition.

Original languageEnglish (US)
Pages (from-to)223-229
Number of pages7
JournalWater Science and Technology
Issue number4-5
StatePublished - 1998
Externally publishedYes
EventProceedings of the 1997 2nd International Conference on Microorganisms in Activated Sludge and Biofilm Processes - Berkeley, CA, USA
Duration: Jul 21 1997Jul 23 1997


  • Activated sludge
  • Membrane bioreactor
  • Modeling
  • Nitrification
  • Nucleic probes
  • Sludge production

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology


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