Modeling of simultaneous growth and storage kinetics variation under unsteady feast conditions for aerobic heterotrophic biomass

Güçlü Insel*, Ateş Yavaşbay, Onur Ozcan, Emine Ubay Cokgor

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


The heterotrophic biomass has the capacity of utilizing substrate predominantly for growth or storage processes under steady-state conditions. In this study, the short-term variations in growth and storage kinetics of activated sludge under disturbed feeding conditions were analyzed using a multi-component biodegradation model. The variations in growth and storage kinetics were investigated with the aid of multi-response modeling and identifiability analysis. It was found that the heterotrophic biomass is able to increase its direct growth activity together with reducing the substrate storage capability under the availability of external substrate. Reducing the sludge age (SRT) from 10 to 2 days increased the maximum specific growth rate, lOHO,Max from 3.9 to 7.0 day-1, but did not considerably affected the maximum storage rate, kStor,OHO. The alteration of sludge age also elevated the half-saturation constant for growth (KS,OHO) from 5 to 25 mg COD/L. The increase in primary growth metabolism together with reduced storage rate was validated by model for two different sludge ages in the availability of external substrate. Aside from having a lower storage capability, the biomass had fast adaptation ability to direct growth process at low SRTs. The alteration of feed conditions was found to have different impacts on storage and growth kinetics. These results are significant and advance the field of activated sludge modeling under dynamic conditions by incorporation of short-term effects. Appropriate modifications including short-term effects in model structure may also reduce dynamic model recalibration efforts in the future.

Original languageEnglish
Pages (from-to)1445-1454
Number of pages10
JournalBioprocess and Biosystems Engineering
Issue number8
Publication statusPublished - Oct 2012


Acknowledgments This study was financially supported for MSc. Projects of Mr. Ates¸ Yavas¸bay and Mr. Onur Ozcan by Research and Development Fund of Istanbul Technical University.

FundersFunder number
Istanbul Teknik Üniversitesi


    • Aerobic growth
    • Feast and famine
    • Respirometry
    • Storage
    • Variable kinetics


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