Formation mechanism of nitrifying granules observed in an aerobic upflow fluidized bed (AUFB) reactor

Satoshi Tsuneda, Y. Ejiri, T. Nagano, A. Hirata

    Research output: Contribution to journalArticle

    29 Citations (Scopus)

    Abstract

    The influences of trace metals in the wastewater and shear stress by aeration were particularly examined to clarify the formation mechanism of nitrifying granules in an aerobic upflow fluidized bed (AUFB) reactor. It was found that Fe added as a trace element to the inorganic wastewater accumulated at the central part of the nitrifying granules. Another result obtained was that suitable shear stress by moderate aeration (0.07-0.20 L/min/L-bed) promoted granulation. Furthermore, it was successfully demonstrated that pre-aggregation of seed sludge using hematite promoted core formation, leading to rapid production of nitrifying granules. From these results, a nitrifying granulation mechanism is proposed: 1) as a first step, nitrifying bacteria aggregate along with Fe precipitation, and then the cores of granules are formed; 2) as a second step, the aggregates grow to be spherical or elliptical in form due to multiplication of the nitrifying bacteria and moderate shear stress in the reactor, and then mature nitrifying granules are produced. Fluorescence in situ hybridization (FISH) analysis successfully visualized the change in the spatial distribution of nitrifying bacteria in the granules, which supports the proposed granulation mechanism.

    Original languageEnglish
    Pages (from-to)27-34
    Number of pages8
    JournalWater Science and Technology
    Volume49
    Issue number11-12
    Publication statusPublished - 2004

    Fingerprint

    nitrifying bacterium
    Granulation
    formation mechanism
    Fluidized beds
    shear stress
    Shear stress
    Bacteria
    aeration
    Wastewater
    wastewater
    Hematite
    Trace elements
    hematite
    Spatial distribution
    trace metal
    Seed
    fluorescence
    Agglomeration
    Fluorescence
    sludge

    Keywords

    • Aerobic upflow fluidized bed (AUFB)
    • Granulation mechanism
    • Nitrifying granule

    ASJC Scopus subject areas

    • Water Science and Technology

    Cite this

    Formation mechanism of nitrifying granules observed in an aerobic upflow fluidized bed (AUFB) reactor. / Tsuneda, Satoshi; Ejiri, Y.; Nagano, T.; Hirata, A.

    In: Water Science and Technology, Vol. 49, No. 11-12, 2004, p. 27-34.

    Research output: Contribution to journalArticle

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