The effect of pH on N2O production under aerobic conditions in a partial nitritation system

Law, Yingyu, Lant, Paul and Yuan, Zhiguo (2011) The effect of pH on N2O production under aerobic conditions in a partial nitritation system. Water Research, 45 18: 5934-5944. doi:10.1016/j.watres.2011.08.055


Author Law, Yingyu
Lant, Paul
Yuan, Zhiguo
Title The effect of pH on N2O production under aerobic conditions in a partial nitritation system
Formatted title
The effect of pH on N2O production under aerobic conditions in a partial nitritation system
Journal name Water Research   Check publisher's open access policy
ISSN 0043-1354
1879-2448
Publication date 2011-11-15
Year available 2011
Sub-type Article (original research)
DOI 10.1016/j.watres.2011.08.055
Open Access Status Not yet assessed
Volume 45
Issue 18
Start page 5934
End page 5944
Total pages 11
Place of publication London, U.K.
Publisher IWA Publishing
Language eng
Subject 2312 Water Science and Technology
2311 Waste Management and Disposal
2310 Pollution
2302 Ecological Modelling
Abstract Ammonia-oxidising bacteria (AOB) are a major contributor to nitrous oxide (N2O) emissions during nitrogen transformation. N2O production was observed under both anoxic and aerobic conditions in a lab-scale partial nitritation system operated as a sequencing batch reactor (SBR). The system achieved 55 +/- 5% conversion of the 1 g NH4+-N/L contained in a synthetic anaerobic digester liquor to nitrite. The N2O emission factor was 1.0 +/- 0.1% of the ammonium converted. pH was shown to have a major impact on the N2O production rate of the AOB enriched culture. In the investigated pH range of 6.0-8.5, the specific N2O production was the lowest between pH 6.0 and 7.0 at a rate of 0.15 +/- 0.01 mg N2O-N/h/g VSS, but increased with pH to a maximum of 0.53 +/- 0.04 mg N2O-N/h/g VSS at pH 8.0. The same trend was also observed for the specific ammonium oxidation rate (AOR) with the maximum AOR reached at pH 8.0. A linear relationship between the N2O production rate and AOR was observed suggesting that increased ammonium oxidation activity may have promoted N2O production. The N2O production rate was constant across free ammonia (FA) and free nitrous acid (FNA) concentrations of 5-78 mg NH3-N/L and 0.15-4.6 mg HNO2-N/L, respectively, indicating that the observed pH effect was not due to changes in FA or FNA concentrations. (C) 2011 Elsevier Ltd. All rights reserved.
Formatted abstract
Ammonia-oxidising bacteria (AOB) are a major contributor to nitrous oxide (N2O) emissions during nitrogen transformation. N2O production was observed under both anoxic and aerobic conditions in a lab-scale partial nitritation system operated as a sequencing batch reactor (SBR). The system achieved 55 ± 5% conversion of the 1 g NH4+-N/L contained in a synthetic anaerobic digester liquor to nitrite. The N2O emission factor was 1.0 ± 0.1% of the ammonium converted. pH was shown to have a major impact on the N2O production rate of the AOB enriched culture. In the investigated pH range of 6.0–8.5, the specific N2O production was the lowest between pH 6.0 and 7.0 at a rate of 0.15 ± 0.01 mg N2O-N/h/g VSS, but increased with pH to a maximum of 0.53 ± 0.04 mg N2O-N/h/g VSS at pH 8.0. The same trend was also observed for the specific ammonium oxidation rate (AOR) with the maximum AOR reached at pH 8.0. A linear relationship between the N2O production rate and AOR was observed suggesting that increased ammonium oxidation activity may have promoted N2O production. The N2O production rate was constant across free ammonia (FA) and free nitrous acid (FNA) concentrations of 5–78 mg NH3-N/L and 0.15–4.6 mg HNO2-N/L, respectively, indicating that the observed pH effect was not due to changes in FA or FNA concentrations.

Highlights ► The N2O production rate varies with pH within the range of 6.0–8.5. ► The pH effect is not due to changes in the FA and FNA concentrations. ► The N2O production rate is linearly correlated to the ammonium oxidation rate. ► Maintaining the pH between 6.4 and 7.0 mitigated the N2O production.
Keyword Nitrous oxide
pH
Anaerobic digester liquor
Ammonia-oxidising bacteria
Partial nitritation
Wastewater treatment
Sequencing batch reactor
Greenhouse gas emissions
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID LP0991765
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2012 Collection
Advanced Water Management Centre Publications
 
Available Versions of this Record
 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 80 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 87 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Tue, 18 Oct 2011, 19:41:40 EST by Professor Paul Lant on behalf of Advanced Water Management Centre