Model-Based Evaluation of N<sub>2</sub>O Production Pathways in the Anammox-Enriched Granular Sludge Cultivated in a Sequencing Batch Reactor

Lu, Xi; Pereira, Tiago Duarte Santos; Al‐Hazmi, Hussein E.; Majtacz, Joanna; Zhou, Qi; Xie, Lin; Mąkinia, Jacek

doi:10.1021/acs.est.7b05611

Cited by 55 publications

(20 citation statements)

References 45 publications

(126 reference statements)

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“…Model evaluation results based on the experimental batch data of (a) NH 4 + , NO 2 − , and NO 3 − , and (B) N 2 O reported in Lu et al () [Color figure can be viewed at wileyonlinelibrary.com]…”

Section: Resultsmentioning

confidence: 99%

“…Two independent experimental datasets previously reported in Wang et al () and Lu et al () that studied N 2 O production dynamics in autotrophic nitrogen removal biofilm/granular systems under different operational conditions were used to test the validity of the defined model.…”

Section: Methodsmentioning

confidence: 99%

“…Data set 2 (Lu et al, ): The N 2 O production behavior was observed in a 10‐L bench‐scale PlexiGlass SBR with biomass retained in the form of granules. The SBR was fed with an inorganic synthetic wastewater containing a mixture of 140 g NH 4 + N/m 3 and 182 g NO 2 − N/m 3 and operated in 3 hr cycles, consisting of 30 min feeding phase, 2 hr mixing phase, 20 min settling phase, and 10 min decanting phase withdrawing an aliquot of 2.5 L. The data for model testing described the dynamic variations of NH 4 + , NO 2 − , NO 3 − , and N 2 O in the SBR for the first 2.5 hr of an operational cycle as a batch test, the low DO of which was derived from atmospheric reoxygenation.…”

Section: Methodsmentioning

confidence: 99%

“…Model testing using Data set 2 reported in Lu et al () was conducted by applying all NH 4 + , NO 2 − , NO 3 − , and N 2 O profiles simultaneously to further verify the defined model. Assuming a biomass density of 100,000 g‐COD/m 3 and a biofilm porosity of 0.75 (Koch et al, ), the number of granules in the SBR was calculated based on the measured median granule size (D 50 = 728 µm) and the mixed liquor volatile suspended solids concentration (2,399 g/m 3 ) reported in Lu et al (). Similar to the aforementioned handling, the biomass composition was decided by reference to the experimentally quantified abundance of microbial species in consideration of slowly biodegradable and inert organics.…”

Section: Methodsmentioning

confidence: 99%

“…Diffusion of soluble components in the biofilm matrix was set with the introduction of reduced diffusion coefficients in water, which are provided in Table S5 (SI). reported in Lu et al (2018). Similar to the aforementioned handling, the biomass composition was decided by reference to the experimentally quantified abundance of microbial species in consideration of slowly biodegradable and inert organics.…”

Section: Model Testing and Simulation Approachmentioning

confidence: 99%

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Nitrous oxide production in autotrophic nitrogen removal granular sludge: A modeling study

Chen

Sin

2019

Biotech & Bioengineering

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The sustainability of autotrophic granular system performing partial nitritation and anaerobic ammonium oxidation (anammox) for complete nitrogen removal is impaired by the production of nitrous oxide (N 2 O). A systematic analysis of the pathways and affecting parameters is, therefore, required for developing N 2 O mitigation strategies.To this end, a mathematical model capable of describing different N 2 O production pathways was defined in this study by synthesizing relevant mechanisms of ammonium-oxidizing bacteria (AOB), nitrite-oxidizing bacteria, heterotrophic bacteria (HB), and anammox bacteria. With the model validity reliably tested and verified using two independent sets of experimental data from two different autotrophic nitrogen removal biofilm/granular systems, the defined model was applied to reveal the underlying mechanisms of N 2 O production in the granular structure as well as the impacts of operating conditions on N 2 O production. The results show that: (a) in the aerobic zone close to the granule surface where AOB contribute to N 2 O production through both the AOB denitrification pathway and the NH 2 OH pathway, the cooccurring HB consume N 2 O produced by AOB but indirectly enhance the N 2 O production by providing NO from NO 2 − reduction for the NH 2 OH pathway, (b) the inner anoxic zone of granules with the dominance of anammox bacteria acts as a sink for NO 2 − diffusing from the outer aerobic zone and, therefore, reduces N 2 O production from the AOB denitrification pathway, (c) operating parameters including bulk DO, influent NH 4 + , and granule size affect the N 2 O production in the granules mainly by regulating the NH 2 OH pathway of AOB, accounting for 34-58% of N 2 O turnover, and (d) the competition between the NH 2 OH pathway and heterotrophic denitrification for nitric oxide leads to the positive role of HB in reducing N 2 O production in the autotrophic nitrogen removal granules, which could be further enhanced in the presence of a proper level of influent organics.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Model Testing and Simulation Approachmentioning

confidence: 99%

See 3 more Smart Citations

Nitrous oxide production in autotrophic nitrogen removal granular sludge: A modeling study

Chen

Sin

2019

Biotech & Bioengineering

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Dynamic modelling of N₂O emissions from a full‐scale granular sludge partial nitritation‐anammox reactor

Wan

Volcke

2022

Biotech & Bioengineering

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Partial nitration-anammox is a resource-efficient pathway for nitrogen removal from wastewater. However, the advantages of this nitrogen removal technology may be counter-acted by the emission of N 2 O, a potent greenhouse gas. In this study, mathematical modelling was applied to analyse N 2 O formation and emission dynamics and to develop N 2 O mitigation strategies for a one-stage partial nitritationanammox granular sludge reactor. Dynamic model calibration for such a full-scale reactor was performed, applying a one-dimensional biofilm model and including several N 2 O formation pathways. Simultaneous calibration of liquid phase concentrations and N 2 O emissions leads to improved model fit compared to their consecutive calibration. The model could quantitatively predict the average N 2 O emissions and qualitatively characterize the N 2 O dynamics, adjusting only seven parameter values. The model was validated with N 2 O data from an independent data set at different aeration conditions. Nitrifier nitrification was identified as the dominating N 2 O formation pathway. Off-gas recirculation as a potential N 2 Oemission reduction strategy was tested by simulation and showed indeed some improvement, be it at the cost of higher aeration energy consumption.

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Nitrous oxide emissions from biofilm processes for wastewater treatment

Sabba

Terada

Wells

et al. 2018

Appl Microbiol Biotechnol

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This paper discusses the microbial basis and the latest research on nitrous oxide (NO) emissions from biofilms processes for wastewater treatment. Conditions that generally promote NO formation in biofilms include (1) low DO values, or spatial DO transitions from high to low within the biofilm; (2) DO fluctuations within biofilm due to varying bulk DO concentrations or varying substrate concentrations; (3) conditions with high reaction rates, which lead to greater formation of intermediates, e.g., hydroxylamine (NHOH) and nitrite (NO), that promote NO formation; and (4) electron donor limitation for denitrification. Formation of NO directly results from the activities of ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA), and heterotrophic denitrifying bacteria. More research is needed on the roles of AOA, comammox, and specialized denitrifying microorganisms. In nitrifying biofilms, higher bulk ammonia (NH) concentrations, higher nitrite (NO) concentrations, lower dissolved oxygen (DO), and greater biofilm thicknesses result in higher NO emissions. In denitrifying biofilms, NO accumulates at low levels as an intermediate and at higher levels at the oxic/anoxic transition regions of the biofilms and where COD becomes limiting. NO formed in the outer regions can be consumed in the inner regions if COD penetrates sufficiently. In membrane-aerated biofilms, where nitrification takes place in the inner, aerobic biofilm region, the exterior anoxic biofilm can serve as a NO sink. Reactors that include variable aeration or air scouring, such as denitrifying filters, trickling filters, or rotating biological contactors (RBCs), can form peaks of NO emissions during or following a scouring or aeration event. NO emissions from biofilm processes depend on the microbial composition, biofilm thickness, substrate concentrations and variability, and reactor type and operation. Given the complexity and difficulty in quantifying many of these factors, it may be difficult to accurately predict emissions for full-scale treatment plants. However, a better understanding of the mechanisms and the impacts of process configurations can help minimize NO emission from biofilm processes for wastewater treatment.

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Model-Based Evaluation of N₂O Production Pathways in the Anammox-Enriched Granular Sludge Cultivated in a Sequencing Batch Reactor

Cited by 55 publications

References 45 publications

Nitrous oxide production in autotrophic nitrogen removal granular sludge: A modeling study

Nitrous oxide production in autotrophic nitrogen removal granular sludge: A modeling study

Dynamic modelling of N₂O emissions from a full‐scale granular sludge partial nitritation‐anammox reactor

Nitrous oxide emissions from biofilm processes for wastewater treatment

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Model-Based Evaluation of N2O Production Pathways in the Anammox-Enriched Granular Sludge Cultivated in a Sequencing Batch Reactor

Cited by 55 publications

References 45 publications

Nitrous oxide production in autotrophic nitrogen removal granular sludge: A modeling study

Nitrous oxide production in autotrophic nitrogen removal granular sludge: A modeling study

Dynamic modelling of N2O emissions from a full‐scale granular sludge partial nitritation‐anammox reactor

Nitrous oxide emissions from biofilm processes for wastewater treatment

Contact Info

Product

Resources

About

Model-Based Evaluation of N₂O Production Pathways in the Anammox-Enriched Granular Sludge Cultivated in a Sequencing Batch Reactor

Dynamic modelling of N₂O emissions from a full‐scale granular sludge partial nitritation‐anammox reactor