Gel-forming exopolysaccharides explain basic differences between structures of aerobic sludge granules and floccular sludges

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Author(s)

  • Thomas Seviour
  • Maite Pijuan
  • Timothy Nicholson
  • Jürg Keller
  • Zhiguo Yuan

Detail(s)

Original languageEnglish
Pages (from-to)4469-4478
Journal / PublicationWater Research
Volume43
Issue number18
Publication statusPublished - Oct 2009
Externally publishedYes

Abstract

The sol-gel transition of extracellular polymeric substances (EPS) derived from sludge flocs and granules is investigated in order to explain basic differences between the two aggregates. A reversible, pH dependent sol-gel transition was observed at pH 9.0-12.0 in EPS extracted from granules. At pH <9 granule EPS existed as a strong gel, indicating that their EPS exist in a gel state at normal operating pH of a wastewater treatment system (i.e. 6.0-8.5). This characteristic transition from solution to strong gel was not observed in any of the EPS samples derived from floccular sludges. A transition to a weak gel was however, observed at pH 4.0-5.0. Enriched exopolysaccharides from the granular EPS exhibited rheological behaviour analogous to the granules and the granule EPS. The critical overlap concentration (c*) of the exopolysaccharide concentrate was 0.33% w/w, similar to the c* of other known bacterial exopolysaccharides. Additionally, the protein content was found to be not contributing to the storage modulus of granule EPS gels. These factors suggest that exopolysaccharides or glycosides were the gelling agent in aerobic sludge granules. Given that EPS derived from aerobic sludge granules and flocs are distinguished by such a sol-strong gel transition, these exopolysaccharides therefore likely play an important role in granulation. © 2009 Elsevier Ltd. All rights reserved.

Research Area(s)

  • Aerobic sludge granules, Extracellular polymeric substances, Floccular sludge, Hydrogels, Sol-gel transition

Bibliographic Note

Publication details (e.g. title, author(s), publication statuses and dates) are captured on an “AS IS” and “AS AVAILABLE” basis at the time of record harvesting from the data source. Suggestions for further amendments or supplementary information can be sent to lbscholars@cityu.edu.hk.

Citation Format(s)

Gel-forming exopolysaccharides explain basic differences between structures of aerobic sludge granules and floccular sludges. / Seviour, Thomas; Pijuan, Maite; Nicholson, Timothy et al.
In: Water Research, Vol. 43, No. 18, 10.2009, p. 4469-4478.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review