Extension of activated sludge model no 1 with two-step nitrification and denitrification processes for operation improvement

George Simion Ostace, Vasile Mircea Cristea, Paulşerban Agachi

    Research output: Contribution to journalArticle

    6 Citations (Scopus)

    Abstract

    The present paper presents an enhanced Activated Sludge Model No. 1 in which nitrification and denitrification are modelled as two-step processes. The nitrification process is considered as a sequence of two steps carried out by two distinct genera of bacteria, with nitrite as an intermediate product. For the denitrification process a parallel approach was used that considers nitrate and nitrite to be directly reduced to molecular nitrogen. The new model is compared to the original Activated Sludge Model No. 1 using the Benchmark Simulation Model No. 1. In order to make the simulation model more realistic the secondary settler was considered to be reactive. The new modelling approach showed different dynamics for the autotrophic biomass and the growth substrate of the heterotrophic biomass, enhancing the agreement with the real process behaviour. The last part of the paper presents the investigation of finding the optimal set-point for a cascade control scheme based on the Model Predictive Controller at the outer control level and three PI controllers at the inner level. The control architecture is designed to keep the nitrate nitrogen level at the end of the aerated zone at predefined set-points. The wastewater treatment plant performance is evaluated using the operational costs criteria. The simulation results show that noteworthy costs can be saved using this control strategy.

    Original languageEnglish
    Pages (from-to)1529-1544
    Number of pages16
    JournalEnvironmental Engineering and Management Journal
    Volume10
    Issue number10
    Publication statusPublished - Oct 2011

    Fingerprint

    Nitrification
    Denitrification
    activated sludge
    nitrification
    denitrification
    nitrite
    Nitrates
    Biomass
    nitrate
    Nitrogen
    simulation
    Controllers
    nitrogen
    Level control
    biomass
    cost
    Wastewater treatment
    Costs
    Bacteria
    substrate

    All Science Journal Classification (ASJC) codes

    • Environmental Engineering
    • Pollution
    • Management, Monitoring, Policy and Law

    Cite this

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    title = "Extension of activated sludge model no 1 with two-step nitrification and denitrification processes for operation improvement",
    abstract = "The present paper presents an enhanced Activated Sludge Model No. 1 in which nitrification and denitrification are modelled as two-step processes. The nitrification process is considered as a sequence of two steps carried out by two distinct genera of bacteria, with nitrite as an intermediate product. For the denitrification process a parallel approach was used that considers nitrate and nitrite to be directly reduced to molecular nitrogen. The new model is compared to the original Activated Sludge Model No. 1 using the Benchmark Simulation Model No. 1. In order to make the simulation model more realistic the secondary settler was considered to be reactive. The new modelling approach showed different dynamics for the autotrophic biomass and the growth substrate of the heterotrophic biomass, enhancing the agreement with the real process behaviour. The last part of the paper presents the investigation of finding the optimal set-point for a cascade control scheme based on the Model Predictive Controller at the outer control level and three PI controllers at the inner level. The control architecture is designed to keep the nitrate nitrogen level at the end of the aerated zone at predefined set-points. The wastewater treatment plant performance is evaluated using the operational costs criteria. The simulation results show that noteworthy costs can be saved using this control strategy.",
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    Extension of activated sludge model no 1 with two-step nitrification and denitrification processes for operation improvement. / Ostace, George Simion; Cristea, Vasile Mircea; Agachi, Paulşerban.

    In: Environmental Engineering and Management Journal, Vol. 10, No. 10, 10.2011, p. 1529-1544.

    Research output: Contribution to journalArticle

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