The effect of pH on the competition between polyphosphate-accumulating organisms and glycogen-accumulating organisms

• Published in: Water research (Oxford) 2005-09, Vol.39 (15), p.3727-3737
• Main Authors: Oehmen, Adrian, Teresa Vives, M., Lu, Huabing, Yuan, Zhiguo, Keller, Jürg
• Format: Article
• Language: English
• Subjects: Acetates - metabolism; activated sludge; Alphaproteobacteria - metabolism; Applied sciences; bacteria; Biodegradation, Environmental; Biological and medical sciences; Bioreactors; Biotechnology; Enhanced biological phosphorus removal (EBPR); Environment and pollution; Exact sciences and technology; extraction; Fluorescence in situ hybridisation (FISH); fluorescence in situ hybridization; Fundamental and applied biological sciences. Psychology; Gammaproteobacteria - metabolism; Glycogen - metabolism; Glycogen-accumulating organisms (GAO); Hydrogen-Ion Concentration; In Situ Hybridization, Fluorescence; Industrial applications and implications. Economical aspects; microbial competition; Other industrial wastes. Sewage sludge; phosphorus; Phosphorus - analysis; Phosphorus - metabolism; Pollution; Polyphosphate-accumulating organisms (PAO); Polyphosphates - metabolism; Propionates - metabolism; volatile fatty acids; Volatile fatty acids (VFA); Wastes; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - metabolism; Water Purification; water treatment; Water treatment and pollution
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2005.06.031

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 (∼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.