Linking the Nitrogen and One-Carbon Cycles – The Impact of Inorganic Carbon Limitation on Ammonia Oxidation and Nitrogen Oxide Emission Rates in Ammonia Oxidizing Bacteria

Khunjar, Wendell; Jiang, Dagang; Murthy, Sudhir; Wett, Bernhard; Chandran, Kartik

doi:10.2175/193864711802721848

Cited by 8 publications

(12 citation statements)

References 10 publications

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“…A previous study by Khunjar et al (2011) observed increased N2O emission under IC limiting conditions using Nitrosomonas europaea, which was contradicted to our findings. Aamand et al (2009) found that the carbonic anhydrase, a ubiquitous enzyme as well as a functional enzyme during CBB cycle (Kim et al, 2012), could potentially utilize NO2 -to generate nitric oxide.…”

Section: The Effect Of Ic On N2o Production By Aobcontrasting

confidence: 99%

“…Therefore, we hypothesize that the indirect dependency of N2O production by AOB on IC be likely due to the important role of IC in linking the energy generating and consuming processes (Khunjar et al, 2011). However, the fundamental mechanism remains to be fully elucidated.…”

Section: The Effect Of Ic On N2o Production By Aobmentioning

confidence: 99%

“…A large variation in N2O emission factor (ratio between N2O nitrogen and ammonia nitrogen load) in both lab-scale (0-95%) and full-scale (0-25%) studies has been reported Law et al, 2012b), which may be due to different sampling methods, various types of cultures and wastewater treatment plants (WWTPs), and highly dynamic conditions in wastewater treatment systems. Increasing evidence shows that dissolved oxygen (DO), NO2 -and inorganic carbon (IC) are the three key factors influencing N2O 9 production by AOB Kampschreur et al, 2007b;Khunjar et al, 2011;Wunderlin et al, 2012). However, the real effects of these key parameters on N2O production by AOB is not clear due to their mutual interferences and the presence of heterotrophic bacteria that would produce/consume N2O.…”

mentioning

confidence: 99%

“…Therefore, it could be expected that the IC concentration could have an impact on N2O production by AOB. Indeed, (Khunjar et al, 2011) suggested IC limitation negatively affected the ammonia removal efficiency as well as the AOB respiration rate, and caused an increase of N2O emission. And the N2O emissions were trigged by IC limiting conditions in nitritation-anammox system (Ma et al, 2015).…”

mentioning

confidence: 99%

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Understanding nitrous oxide production by ammonia oxidizing bacteria in an enriched nitrifying sludge

Peng¹

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Nitrous oxide (N2O) is not only a potent greenhouse gas with approximately 300 times global warming potential of carbon dioxide (CO2), but it is also a major sink for stratospheric ozone.Wastewater treatment systems are a recognized source of N2O. During biological wastewater treatment, N2O is mainly generated from biological nitrogen removal (BNR), which involves both nitrification and denitrification. Recently, ammonia-oxidizing bacteria (AOB) are identified as the major contributor to N2O production in wastewater treatment plants. However, the mechanisms of N2O production by AOB are still not fully understood. This thesis aims to experimentally assess and mathematically model the effect of several key operational parameters on N2O production by AOB as well as the contributions of different N2O production pathways to total N2O emission.In order to achieve the aim, a nitrifying culture comprising primarily AOB and nitrite oxidizing bacteria (NOB) was enriched in a sequencing batch reactor (SBR). The reactor was fed with synthetic water containing 1 g N/L ammonium (NH4 + ) and performed complete nitrification with 100% conversion of NH4 + to nitrate (NO3 -). This thesis firstly investigated the effect of dissolved oxygen (DO) on the N2O production by the enriched nitrifying sludge. On this occasion nitrite accumulation was minimised by augmenting nitrite (NO2 -) oxidation through the addition of an enriched NOB sludge into the batch reactor. It was demonstrated that the specific N2O production rate (N2OR) increased from 0 to 1.9 ± 0.09 (n=3) mg N/hr/g VSS with an increase of DO concentration from 0 to 3.0 mg O2/L, whereas the N2O emission factor (the ratio between N2O nitrogen emitted and the ammonium nitrogen converted) decreased from 10.6 ± 1.7% (n=3) to 2.4 ± 0.1% (n=3). The site preference measurements, which is calculated as the difference between central and terminal nitrogen isotopomer signatures in N2O molecule, indicated that both the AOB denitrification and hydroxylamine (NH2OH) oxidation pathways contributed to N2O production, and DO had an important effect on the relative contributions of the two pathways. This finding is supported by analysis of the process data using an N2O model integrating both pathways. As DO increased from 0.2 to 3.0 mg O2/L, the contribution of AOB denitrification decreased from 92% − 95% to 66% − 73%, accompanied by a corresponding increase in the contribution by the NH2OH oxidation pathway. IIThe combined effect of NO2 -and DO on N2O production by AOB was further studied using the enriched nitrifying culture. At each investigated DO level, both the biomass specific N2O production rate and the N2O emission factor increased as NO2 -concentration increased from 3 mg N/L to 50 mg N/L. However, at each investigated NO2 -level, the maximum biomass specific N2Oproduction rate occurred at DO of 0.85 mg O2/L, while the N2O emission factor decreased as DO increased from 0.35 to 3.5 mg O2/L. The analysis of the process data using the two-pathway N2O model indicated that the con...

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Section: The Effect Of Ic On N2o Production By Aobcontrasting

confidence: 99%

Section: The Effect Of Ic On N2o Production By Aobmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Understanding nitrous oxide production by ammonia oxidizing bacteria in an enriched nitrifying sludge

Peng¹

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“…Therefore, it could be expected that the IC concentration could have an impact on N 2 O production by AOB. Indeed, a recent study by Khunjar et al (2011) suggested IC limitation negatively affected the ammonia removal efficiency as well as the AOB respiration rate, and caused an increase of N 2 O emission. However, there has been a lack of understanding on the dependency of N 2 O production by AOB on the IC concentration.…”

Section: Introductionmentioning

confidence: 99%

N2O production by ammonia oxidizing bacteria in an enriched nitrifying sludge linearly depends on inorganic carbon concentration

Peng

et al. 2015

Water Research

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Heterotrophs are key contributors to nitrous oxide production in activated sludge under low C‐to‐N ratios during nitrification—Batch experiments and modeling

Domingo-Félez

Pellicer-Nàcher

Petersen

et al. 2016

Biotech & Bioengineering

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Nitrous oxide (N O), a by-product of biological nitrogen removal during wastewater treatment, is produced by ammonia-oxidizing bacteria (AOB) and heterotrophic denitrifying bacteria (HB). Mathematical models are used to predict N O emissions, often including AOB as the main N O producer. Several model structures have been proposed without consensus calibration procedures. Here, we present a new experimental design that was used to calibrate AOB-driven N O dynamics of a mixed culture. Even though AOB activity was favoured with respect to HB, oxygen uptake rates indicated HB activity. Hence, rigorous experimental design for calibration of autotrophic N O production from mixed cultures is essential. The proposed N O production pathways were examined using five alternative process models confronted with experimental data inferred. Individually, the autotrophic and heterotrophic denitrification pathway could describe the observed data. In the best-fit model, which combined two denitrification pathways, the heterotrophic was stronger than the autotrophic contribution to N O production. Importantly, the individual contribution of autotrophic and heterotrophic to the total N O pool could not be unambiguously elucidated solely based on bulk N O measurements. Data on NO would increase the practical identifiability of N O production pathways. Biotechnol. Bioeng. 2017;114: 132-140. © 2016 Wiley Periodicals, Inc.

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Linking the Nitrogen and One-Carbon Cycles – The Impact of Inorganic Carbon Limitation on Ammonia Oxidation and Nitrogen Oxide Emission Rates in Ammonia Oxidizing Bacteria

Cited by 8 publications

References 10 publications

Understanding nitrous oxide production by ammonia oxidizing bacteria in an enriched nitrifying sludge

Understanding nitrous oxide production by ammonia oxidizing bacteria in an enriched nitrifying sludge

N2O production by ammonia oxidizing bacteria in an enriched nitrifying sludge linearly depends on inorganic carbon concentration

Heterotrophs are key contributors to nitrous oxide production in activated sludge under low C‐to‐N ratios during nitrification—Batch experiments and modeling

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