Effect of long-term idle periods on the performance of sequencing batch reactors

Eberhard Friedrich Morgenroth, A. Obermayer, E. Arnold, A. Brühl, M. Wagner, P. A. Wilderer

    Research output: Contribution to journalJournal articleResearchpeer-review


    Sludge storage can be used as an effective control handle to adjust plant capacity to large influent variations. The sequencing batch reactor (SBR) technology is well suited for temporary sludge storage because reactors can easily be switched off individually and operated in an idle mode. In this study experimental results on the effect of long term (weeks) idle periods on nitrogen removal are presented. The SBRs were operated with idle times ranging from 6 to 20 days. Batch experiments were performed where sludge was stored without the addition of any substrate for 7 weeks. In the SBRs, repeated long-term idle phases had only a minor effect on ammonia oxidation. The nitrite oxidation process was more sensitive to long idle phases resulting in temporary nitrite accumulation in the SBRs. Quantitative gene probe analyses demonstrated that the decay of ammonia oxidizers was slower than the decay of nitrite oxidizers which in turn decayed slower than heterotrophic bacteria.
    Original languageEnglish
    JournalWater Science and Technology
    Issue number1
    Pages (from-to)105-113
    Publication statusPublished - 2000


    • gene probes
    • sequencing batch reactor (SBR)
    • lysis
    • idle period
    • fluorescent in situ hybridization (FISH)
    • decay

    Cite this

    Morgenroth, E. F., Obermayer, A., Arnold, E., Brühl, A., Wagner, M., & Wilderer, P. A. (2000). Effect of long-term idle periods on the performance of sequencing batch reactors. Water Science and Technology, 41(1), 105-113.