title: The effect of pH on the competition between polyphosphate-accumulating organisms and glycogen-accumulating organisms.
abstract: In enhanced biological phosphorus removal (EBPR) processes, glycogen-accumulating organisms (GAOs) may compete with polyphosphate-accumulating organisms (PAOs) for the often-limited carbon substrates, potentially resulting in disturbances to phosphorus removal. A detailed investigation of the effect of pH on the competition between PAOs and GAOs is reported in this study. The results show that a high external pH ( approximately 8) provided PAOs with an advantage over GAOs in EBPR systems. The phosphorus removal performance improved due to a population shift favouring PAOs over GAOs, which was shown through both chemical and microbiological methods. Two lab-scale reactors fed with propionate as the carbon source were subjected to an increase in pH from 7 to 8. The phosphorus removal and PAO population (as measured by quantitative fluorescence in situ hybridisation analysis of "Candidatus Accumulibacter phosphatis") increased in each system, where the PAOs appeared to out-compete a group of Alphaproteobacteria GAOs. A considerable improvement in the P removal was also observed in an acetate fed reactor, where the GAO population (primarily "Candidatus Competibacter phosphatis") decreased substantially after a similar increase in the pH. The results from this study suggest that pH could be used as a control parameter to reduce the undesirable proliferation of GAOs and improve phosphorus removal in EBPR systems.
authors.affiliation: Advanced Wastewater Management Centre (AWMC), The University of Queensland, St. Lucia, Brisbane 4072, Australia. adriano@dq.fct.unl.pt
authors.forename: Adrian
authors.initials: A
authors.lastname: Oehmen
authors.forename: M
authors.initials: M
authors.lastname: Teresa Vives
authors.forename: Huabing
authors.initials: H
authors.lastname: Lu
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Yuan
authors.forename: Jürg
authors.initials: J
authors.lastname: Keller
mesh_terms: D000085:Acetates / Q000378:metabolism; D020561:Alphaproteobacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019149:Bioreactors; D020563:Gammaproteobacteria / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D017404:In Situ Hybridization, Fluorescence; D010758:Phosphorus / Q000032:analysis / Q000378:metabolism*; D011122:Polyphosphates / Q000378:metabolism; D011422:Propionates / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*; D018508:Water Purification
chemical_list: D000085:Acetates; D011122:Polyphosphates; D011422:Propionates; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D006003:Glycogen