Butyrate can support PAOs but not GAOs in tropical climates

Glycogen accumulating organisms (GAOs) are thought to compete with polyphosphate accumulating organisms (PAOs) for the often-limiting carbon sources available in wastewater, deteriorating enhanced biological phosphorus removal (EBPR) performance at high temperatures. Fermentation liquids are often u...

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Main Authors: Wang, Li, Liu, Jianbo, Oehmen, Adrian, Le, Chencheng, Geng, Yikun, Zhou, Yan
Other Authors: Interdisciplinary Graduate School (IGS)
Format: Article
Language:English
Published: 2022
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Online Access:https://hdl.handle.net/10356/159590
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spelling sg-ntu-dr.10356-1595902022-06-28T01:12:06Z Butyrate can support PAOs but not GAOs in tropical climates Wang, Li Liu, Jianbo Oehmen, Adrian Le, Chencheng Geng, Yikun Zhou, Yan Interdisciplinary Graduate School (IGS) School of Civil and Environmental Engineering Nanyang Environment and Water Research Institute Advanced Environmental Biotechnology Centre (AEBC) Engineering::Environmental engineering Butyrate Sludge Fermentation Glycogen accumulating organisms (GAOs) are thought to compete with polyphosphate accumulating organisms (PAOs) for the often-limiting carbon sources available in wastewater, deteriorating enhanced biological phosphorus removal (EBPR) performance at high temperatures. Fermentation liquids are often used to provide an additional carbon source supply in EBPR processes, where butyrate is known to be an important volatile fatty acid (VFA) produced in sludge fermentation. Nevertheless, the impact of butyrate on the PAO-GAO competition is not well understood especially at high temperature. The results of this study demonstrate that butyrate, as a supplemental or sole carbon source, could be promising for EBPR in tropical climates. When the carbon source was gradually changed from acetate to butyrate, a substantial PAO population was found under both conditions, despite a substantial shift in the abundance of Candidatus Accumulibacter phosphatis (decreased from 37.4% to 13.9%) to Rhodocyclaceae (increased from 2.0% to 14.5%), where both organisms likely played an important role in P-removal. Thus, a relatively stable P removal performance was realized throughout the whole operation period. Nevertheless, butyrate had a negative impact on GAOs. The biomass concentration and microbial diversity continually decreased in the GAO reactor, and Candidatus Competibacter phosphatis reduced from 27.3% to 6.2%, where the dominant population was replaced by Zoogloea. With the addition of butyrate as carbon source, the total amount of synthesized PHAs reduced in both PAO and GAO cultures and the composition of PHA was greatly changed. The presence of a novel PHA fraction (PHH) may disturb the microbial activity in the aerobic phase, where the GAO culture was more severely affected. Glycogen cycling also seemed to be limited in both reactors. This could reduce the GAO metabolism in both cultures and favor PAOs and P removal. Furthermore, the biomass growth rate of the PAO culture was higher than that of GAO when fed with butyrate, which also provides PAO a competitive advantage. All the above results indicate that butyrate could not be well metabolized by GAOs, but could provide PAOs a competitive advantage. Thus, mixed VFAs (i.e. acetate, propionate and butyrate) are likely to favor PAOs over GAOs in EBPR processes operated in warm climates, where the impact of substantial butyrate fractions represents an advantage towards successful process operation. Nanyang Technological University The authors are grateful for the financial support provided by the Advanced Environmental Biotechnology Centre (AEBC) of Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, Singapore, and the Research Fund for the Doctoral Program of Singapore and Interdisciplinary Graduate School of Nanyang Technological University. 2022-06-28T01:12:05Z 2022-06-28T01:12:05Z 2021 Journal Article Wang, L., Liu, J., Oehmen, A., Le, C., Geng, Y. & Zhou, Y. (2021). Butyrate can support PAOs but not GAOs in tropical climates. Water Research, 193, 116884-. https://dx.doi.org/10.1016/j.watres.2021.116884 0043-1354 https://hdl.handle.net/10356/159590 10.1016/j.watres.2021.116884 33556694 2-s2.0-85100383962 193 116884 en Water Research © 2021 Elsevier Ltd. All rights reserved.
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Environmental engineering
Butyrate
Sludge Fermentation
spellingShingle Engineering::Environmental engineering
Butyrate
Sludge Fermentation
Wang, Li
Liu, Jianbo
Oehmen, Adrian
Le, Chencheng
Geng, Yikun
Zhou, Yan
Butyrate can support PAOs but not GAOs in tropical climates
description Glycogen accumulating organisms (GAOs) are thought to compete with polyphosphate accumulating organisms (PAOs) for the often-limiting carbon sources available in wastewater, deteriorating enhanced biological phosphorus removal (EBPR) performance at high temperatures. Fermentation liquids are often used to provide an additional carbon source supply in EBPR processes, where butyrate is known to be an important volatile fatty acid (VFA) produced in sludge fermentation. Nevertheless, the impact of butyrate on the PAO-GAO competition is not well understood especially at high temperature. The results of this study demonstrate that butyrate, as a supplemental or sole carbon source, could be promising for EBPR in tropical climates. When the carbon source was gradually changed from acetate to butyrate, a substantial PAO population was found under both conditions, despite a substantial shift in the abundance of Candidatus Accumulibacter phosphatis (decreased from 37.4% to 13.9%) to Rhodocyclaceae (increased from 2.0% to 14.5%), where both organisms likely played an important role in P-removal. Thus, a relatively stable P removal performance was realized throughout the whole operation period. Nevertheless, butyrate had a negative impact on GAOs. The biomass concentration and microbial diversity continually decreased in the GAO reactor, and Candidatus Competibacter phosphatis reduced from 27.3% to 6.2%, where the dominant population was replaced by Zoogloea. With the addition of butyrate as carbon source, the total amount of synthesized PHAs reduced in both PAO and GAO cultures and the composition of PHA was greatly changed. The presence of a novel PHA fraction (PHH) may disturb the microbial activity in the aerobic phase, where the GAO culture was more severely affected. Glycogen cycling also seemed to be limited in both reactors. This could reduce the GAO metabolism in both cultures and favor PAOs and P removal. Furthermore, the biomass growth rate of the PAO culture was higher than that of GAO when fed with butyrate, which also provides PAO a competitive advantage. All the above results indicate that butyrate could not be well metabolized by GAOs, but could provide PAOs a competitive advantage. Thus, mixed VFAs (i.e. acetate, propionate and butyrate) are likely to favor PAOs over GAOs in EBPR processes operated in warm climates, where the impact of substantial butyrate fractions represents an advantage towards successful process operation.
author2 Interdisciplinary Graduate School (IGS)
author_facet Interdisciplinary Graduate School (IGS)
Wang, Li
Liu, Jianbo
Oehmen, Adrian
Le, Chencheng
Geng, Yikun
Zhou, Yan
format Article
author Wang, Li
Liu, Jianbo
Oehmen, Adrian
Le, Chencheng
Geng, Yikun
Zhou, Yan
author_sort Wang, Li
title Butyrate can support PAOs but not GAOs in tropical climates
title_short Butyrate can support PAOs but not GAOs in tropical climates
title_full Butyrate can support PAOs but not GAOs in tropical climates
title_fullStr Butyrate can support PAOs but not GAOs in tropical climates
title_full_unstemmed Butyrate can support PAOs but not GAOs in tropical climates
title_sort butyrate can support paos but not gaos in tropical climates
publishDate 2022
url https://hdl.handle.net/10356/159590
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