Abstract

Activated sludge in a sequencing batch reactor (SBR) is subjected to alternating feast-and-famine conditions, which may result in the enhanced production of microbial products: extracellular polymeric substances (EPS), soluble microbial products (SMP), and internal storage products (XSTO). In this work, the long-term formation of these three microbial products by activated sludge in an SBR is investigated using an expanded unified model with a parallel experimental study. We also use the model to compare the impacts in an SBR to those in a continuous-flow activated sludge system. The model captures all experimental trends for all components with solids retention time (SRT) for global steady state and within a cycle. At an SRT of 20 days, the active microorganisms constitute about 28% of the mixed liquor volatile suspended solids (MLVSS); the remaining biomass is comprised of residual inert biomass (XI) of 40%, EPS of 31%, and XSTO of ∼1%. The active biomass becomes a smaller fraction with the increasing SRT, while the inert biomass becomes increasingly dominant. For soluble components, effluent chemical oxygen demand (COD) is dominated by SMP, which varies to some degree in a cycle, peaking as external substrate becomes depleted. Within the SBR cycle, external substrate (S) declines strongly in the first part of the cycle, and SMP shows a small peak at the time of S depletion. XSTO is the only biomass component that varies significantly during the cycle. It peaks at the time that the input substrate (S) is depleted. Simulation for a continuous-flow activated sludge system and comparison with an SBR reveals that the constant " famine" conditions of the continuous system lead to lower EPS and XSTO, but higher MLVSS and XI.

Original languageEnglish (US)
Pages (from-to)3787-3796
Number of pages10
JournalWater Research
Volume44
Issue number13
DOIs
StatePublished - Jul 2010

Fingerprint

Batch reactors
Biomass
Sewage
activated sludge
biomass
Starvation
famine
substrate
Substrates
Biological Oxygen Demand Analysis
Chemical oxygen demand
Microorganisms
Effluents
chemical oxygen demand
product
reactor
experimental study
microorganism
effluent
simulation

Keywords

  • Activated sludge
  • Extracellular polymeric substances (EPS)
  • Internal storage products (X)
  • Sequencing batch reactor (SBR)
  • Solids retention time (SRT)
  • Soluble microbial products (SMP)

ASJC Scopus subject areas

  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution
  • Ecological Modeling
  • Medicine(all)

Cite this

Long-term formation of microbial products in a sequencing batch reactor. / Ni, Bing Jie; Rittmann, Bruce; Fang, Fang; Xu, Juan; Yu, Han Qing.

In: Water Research, Vol. 44, No. 13, 07.2010, p. 3787-3796.

Research output: Contribution to journalArticle

Ni, Bing Jie ; Rittmann, Bruce ; Fang, Fang ; Xu, Juan ; Yu, Han Qing. / Long-term formation of microbial products in a sequencing batch reactor. In: Water Research. 2010 ; Vol. 44, No. 13. pp. 3787-3796.
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