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Article: Selective sludge discharge as the determining factor in SBR aerobic granulation: Numerical modelling and experimental verification

TitleSelective sludge discharge as the determining factor in SBR aerobic granulation: Numerical modelling and experimental verification
Authors
Issue Date2009
PublisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/watres
Citation
Water Research, 2009, v. 43 n. 14, p. 3387-3396 How to Cite?
AbstractNumerical simulation and laboratory experiments were conducted to investigate the determining factor and the underlying mechanism in aerobic sludge granulation in a sequencing batch reactor (SBR). In the numerical simulation, a sectional approach was used to develop a model to describe the biomass dynamics during the granulation process. The growth of different classes of the SBR sludge with different substrate uptake rates and different sludge discharge ratios was simulated. The results indicate that the selective discharge of slow-settling sludge flocs is the key determining factor for granulation. In the laboratory study, experiments were conducted with two identical 2.4-L SBRs, R1 and R2, using different sludge discharge methods - the selective discharge of slow-settling sludge flocs for R1, and mixed, unselective sludge discharge for R2. The SBRs were fed with glucose-based synthetic wastewater at a chemical oxygen demand (COD) loading rate of 1.5 kg/m3-d. The evolution of the microbial community during the experimental process was monitored using the molecular techniques of polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE) and clone library analysis. Sludge granulation was achieved in less than three weeks in R1, whereas the sludge in R2 remained in the form of flocs. However, some bacterial species had a significant presence in both the R1 granules and the R2 flocs. The results suggest that aerobic granulation may not require the dominance of any particular species. Small and loose sludge flocs were found to have an advantage over larger and dense granules in substrate uptake. Thus, discharge of loose flocs would remove these competitors from the system and makes the substrate more available for uptake and utilisation by biomass in the attached-growth form, resulting in sludge granulation. © 2009 Elsevier Ltd. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/58501
ISSN
2015 Impact Factor: 5.991
2015 SCImago Journal Rankings: 2.772
ISI Accession Number ID
Funding AgencyGrant Number
Research Grants Council (RGC) of the Hong Kong SAR GovernmentN-HKU737/04
HKU7144/E07
Natural Science Foundation of China50828802
Funding Information:

This research was supported by grants N-HKU737/04 and HKU7144/E07 from the Research Grants Council (RGC) of the Hong Kong SAR Government and grant 50828802 from the Natural Science Foundation of China. The technical assistance of Mr Keith C.H. Wong is highly appreciated.

References

 

DC FieldValueLanguage
dc.contributor.authorLi, AJen_HK
dc.contributor.authorLi, XYen_HK
dc.date.accessioned2010-05-31T03:31:32Z-
dc.date.available2010-05-31T03:31:32Z-
dc.date.issued2009en_HK
dc.identifier.citationWater Research, 2009, v. 43 n. 14, p. 3387-3396en_HK
dc.identifier.issn0043-1354en_HK
dc.identifier.urihttp://hdl.handle.net/10722/58501-
dc.description.abstractNumerical simulation and laboratory experiments were conducted to investigate the determining factor and the underlying mechanism in aerobic sludge granulation in a sequencing batch reactor (SBR). In the numerical simulation, a sectional approach was used to develop a model to describe the biomass dynamics during the granulation process. The growth of different classes of the SBR sludge with different substrate uptake rates and different sludge discharge ratios was simulated. The results indicate that the selective discharge of slow-settling sludge flocs is the key determining factor for granulation. In the laboratory study, experiments were conducted with two identical 2.4-L SBRs, R1 and R2, using different sludge discharge methods - the selective discharge of slow-settling sludge flocs for R1, and mixed, unselective sludge discharge for R2. The SBRs were fed with glucose-based synthetic wastewater at a chemical oxygen demand (COD) loading rate of 1.5 kg/m3-d. The evolution of the microbial community during the experimental process was monitored using the molecular techniques of polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE) and clone library analysis. Sludge granulation was achieved in less than three weeks in R1, whereas the sludge in R2 remained in the form of flocs. However, some bacterial species had a significant presence in both the R1 granules and the R2 flocs. The results suggest that aerobic granulation may not require the dominance of any particular species. Small and loose sludge flocs were found to have an advantage over larger and dense granules in substrate uptake. Thus, discharge of loose flocs would remove these competitors from the system and makes the substrate more available for uptake and utilisation by biomass in the attached-growth form, resulting in sludge granulation. © 2009 Elsevier Ltd. All rights reserved.en_HK
dc.languageengen_HK
dc.publisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/watresen_HK
dc.relation.ispartofWater Researchen_HK
dc.subject.meshAerobiosisen_HK
dc.subject.meshBiological Evolutionen_HK
dc.subject.meshBioreactors - microbiology - standardsen_HK
dc.subject.meshComputer Simulationen_HK
dc.subject.meshFlocculationen_HK
dc.subject.meshModels, Chemicalen_HK
dc.subject.meshOrganic Chemicals - metabolismen_HK
dc.subject.meshParticle Sizeen_HK
dc.subject.meshPhylogenyen_HK
dc.subject.meshReproducibility of Resultsen_HK
dc.subject.meshSewage - microbiologyen_HK
dc.titleSelective sludge discharge as the determining factor in SBR aerobic granulation: Numerical modelling and experimental verificationen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0043-1354&volume=43&spage=3387&epage=3396&date=2009&atitle=Selective+sludge+discharge+as+the+determining+factor+in+SBR+aerobic+granulation:+numerical+modelling+and+experimental+verificationen_HK
dc.identifier.emailLi, XY:xlia@hkucc.hku.hken_HK
dc.identifier.authorityLi, XY=rp00222en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.watres.2009.05.004en_HK
dc.identifier.pmid19505707-
dc.identifier.scopuseid_2-s2.0-67649984481en_HK
dc.identifier.hkuros164565en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-67649984481&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume43en_HK
dc.identifier.issue14en_HK
dc.identifier.spage3387en_HK
dc.identifier.epage3396en_HK
dc.identifier.eissn1879-2448-
dc.identifier.isiWOS:000268993700005-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridLi, AJ=24338209600en_HK
dc.identifier.scopusauthoridLi, XY=26642887900en_HK
dc.identifier.citeulike4799230-

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