Comparison of the modeling approach between membrane bioreactor and conventional activated sludge processes

Tao Jiang*, Gürkan Sin, Henri Spanjers, Ingmar Nopens, Maria D. Kennedy, Walter Van Der Meer, Harry Futselaar, Gary Amy, Peter A. Vanrolleghem

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

31 Citations (Scopus)


Activated sludge models (ASM) have been developed and largely applied in conventional activated sludge (CAS) systems. The applicability of ASM to model membrane bioreactors (MBR) and the differences in modeling approaches have not been studied in detail. A laboratory-scale MBR was modeled using ASM2d. It was found that the ASM2d model structure can still be used for MBR modeling. There are significant differences related to ASM modeling. First, a lower maximum specific growth rate for MBR nitrifiers was estimated. Independent experiments demonstrated that this might be attributed to the inhibition effect of soluble microbial products (SMP) at elevated concentration. Second, a greater biomass affinity to oxygen and ammonium was found, which was probably related to smaller MBR sludge flocs. Finally, the membrane throughput during membrane backwashing/relaxation can be normalized and the membrane can be modeled as a continuous flow-through point separator. This simplicity has only a minor effect on ASM simulation results; however, it significantly improved simulation speed.

Original languageEnglish
Pages (from-to)432-440
Number of pages9
JournalWater Environment Research
Issue number4
Publication statusPublished - 2009
Externally publishedYes


  • Biological nutrient removal
  • Conventional activated sludge
  • Membrane bioreactor
  • Modeling
  • Soluble microbial products


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