Understanding the properties of aerobic sludge granules as hydrogels

Seviour, Thomas, Pijuan, Maite, Nicholson, Timothy, Keller, Jurg and Yuan, Zhiguo (2009) Understanding the properties of aerobic sludge granules as hydrogels. Biotechnology and Bioengineering, 102 5: 1483-1493. doi:10.1002/bit.22164


Author Seviour, Thomas
Pijuan, Maite
Nicholson, Timothy
Keller, Jurg
Yuan, Zhiguo
Title Understanding the properties of aerobic sludge granules as hydrogels
Journal name Biotechnology and Bioengineering   Check publisher's open access policy
ISSN 0006-3592
Publication date 2009-04
Year available 2008
Sub-type Article (original research)
DOI 10.1002/bit.22164
Volume 102
Issue 5
Start page 1483
End page 1493
Total pages 11
Place of publication New York, USA
Publisher John Wiley and Sons
Collection year 2009
Language eng
Subject C1
770402 Land and water management
100204 Environmental Biotechnology Diagnostics (incl. Biosensors)
1002 Environmental Biotechnology
090409 Wastewater Treatment Processes
Abstract Aerobic sludge granules are larger, denser microbial aggregates than activated sludge flocs with a smoother and more regular surface, which facilitates greater wastewater treatment intensity. Factors important in their growth are still poorly understood, which is an impediment to the construction and operation of full-scale aerobic sludge granule processes. Data in this article obtained with granules treating an abattoir wastewater provide evidence that aerobic sludge granules are hydrogels. The results also demonstrate a method for characterizing macromolecular associations. The rheological profile of these granules was found to be analogous with that of typical polymer gels. Water uptake or swelling reflects an equilibrium between granule elastic modulus and osmotic pressure, whereby uptake is increased by reducing solute concentration or the elastic modulus. A weakening of the extracellular polymeric substance (EPS) matrix as demonstrated with mechanical spectroscopy was induced by several environmental factors including temperature, pH and ionic strength. Uniform and elastic deformation was observed at low strain. Enzymatic degradation studies indicate that proteins and a-polysaccharides were themajor granule structuralmaterials. The aerobic sludge granules in the current study were therefore protein–polysaccharide composite physical hydrogels. While aerobic sludge granules treating an abattoir wastewater are used as a case study, many of the fundamental principles detailed here are relevant to other granulation processes. The paradigm established in this study can potentially be applied to better understand the formation of aerobic sludge granules and thus overcome a hurdle in the acceptance of aerobic sludge granulation as an alternative to more traditional wastewater treatment processes. Biotechnol. Bioeng. 2009;102: 1483–1493.
Keyword Aerobic
Sludge
Granules
Hydrogels
Rheology
Q-Index Code C1
Q-Index Status Confirmed Code

 
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Created: Tue, 23 Jun 2009, 12:34:35 EST by Sarah Borsellino on behalf of Advanced Water Management Centre