Modelling N2O dynamics of activated sludge biomass: Uncertainty analysis and pathway contributions

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Modelling N2O dynamics of activated sludge biomass: Uncertainty analysis and pathway contributions. / Domingo-Felez, Carlos; Smets, Barth F.

In: Chemical Engineering Journal, Vol. 379, 122311, 2020.

Research output: Contribution to journalJournal article – Annual report year: 2020Researchpeer-review

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@article{e72667e33e674347b6d56a56df4711cb,
title = "Modelling N2O dynamics of activated sludge biomass: Uncertainty analysis and pathway contributions",
abstract = "Nitrous oxide (N2O) is a potent greenhouse gas emitted during biological wastewater treatment. A pseudo-mechanistic model describing three biological pathways for nitric oxide (NO) and N2O production was calibrated for mixed culture biomass from an activated sludge process using laboratory-scale experiments. The model (NDHA) comprehensively describes N2O producing pathways by both autotrophic ammonium oxidizing bacteria and heterotrophic bacteria. Extant respirometric assays and anaerobic batch experiments were designed to calibrate endogenous and exogenous processes (heterotrophic denitrification and autotrophic ammonium/nitrite oxidation) together with the associated net N2O production. Ten parameters describing heterotrophic processes and seven for autotrophic processes were accurately estimated (variance/mean <25{\%}). The model predicted accurately NO and N2O dynamics at varying dissolved oxygen, ammonium and nitrite levels, and was validated against an independent set of experiments with the same biomass. In aerobic ammonium oxidation experiments the nitrifier denitrification and heterotrophic denitrification estimated pathway contributions increased at high nitrite and low oxygen concentrations; while the nitrifier nitrification pathway showed the largest contribution at high dissolved oxygen levels. The uncertainty of N2O emissions during model calibration is commonly overlooked, which limits the confidence of model-based mitigation strategies. Here we show that the precision of the estimated parameters resulted in a low uncertainty of the N2O emission factors during aerobic ammonium oxidation at DO ≈ 2.0 mg/L (1.2 ± 0.1{\%}) and DO ≈ 0.5 mg/L (4.6 ± 0.6{\%}).",
keywords = "Nitrous oxide, activated sludge, Modelling, Uncertainty, Respirometry",
author = "Carlos Domingo-Felez and Smets, {Barth F.}",
year = "2020",
doi = "10.1016/j.cej.2019.122311",
language = "English",
volume = "379",
journal = "Biochemical Engineering Journal",
issn = "1369-703X",
publisher = "Elsevier B.V.",

}

RIS

TY - JOUR

T1 - Modelling N2O dynamics of activated sludge biomass: Uncertainty analysis and pathway contributions

AU - Domingo-Felez, Carlos

AU - Smets, Barth F.

PY - 2020

Y1 - 2020

N2 - Nitrous oxide (N2O) is a potent greenhouse gas emitted during biological wastewater treatment. A pseudo-mechanistic model describing three biological pathways for nitric oxide (NO) and N2O production was calibrated for mixed culture biomass from an activated sludge process using laboratory-scale experiments. The model (NDHA) comprehensively describes N2O producing pathways by both autotrophic ammonium oxidizing bacteria and heterotrophic bacteria. Extant respirometric assays and anaerobic batch experiments were designed to calibrate endogenous and exogenous processes (heterotrophic denitrification and autotrophic ammonium/nitrite oxidation) together with the associated net N2O production. Ten parameters describing heterotrophic processes and seven for autotrophic processes were accurately estimated (variance/mean <25%). The model predicted accurately NO and N2O dynamics at varying dissolved oxygen, ammonium and nitrite levels, and was validated against an independent set of experiments with the same biomass. In aerobic ammonium oxidation experiments the nitrifier denitrification and heterotrophic denitrification estimated pathway contributions increased at high nitrite and low oxygen concentrations; while the nitrifier nitrification pathway showed the largest contribution at high dissolved oxygen levels. The uncertainty of N2O emissions during model calibration is commonly overlooked, which limits the confidence of model-based mitigation strategies. Here we show that the precision of the estimated parameters resulted in a low uncertainty of the N2O emission factors during aerobic ammonium oxidation at DO ≈ 2.0 mg/L (1.2 ± 0.1%) and DO ≈ 0.5 mg/L (4.6 ± 0.6%).

AB - Nitrous oxide (N2O) is a potent greenhouse gas emitted during biological wastewater treatment. A pseudo-mechanistic model describing three biological pathways for nitric oxide (NO) and N2O production was calibrated for mixed culture biomass from an activated sludge process using laboratory-scale experiments. The model (NDHA) comprehensively describes N2O producing pathways by both autotrophic ammonium oxidizing bacteria and heterotrophic bacteria. Extant respirometric assays and anaerobic batch experiments were designed to calibrate endogenous and exogenous processes (heterotrophic denitrification and autotrophic ammonium/nitrite oxidation) together with the associated net N2O production. Ten parameters describing heterotrophic processes and seven for autotrophic processes were accurately estimated (variance/mean <25%). The model predicted accurately NO and N2O dynamics at varying dissolved oxygen, ammonium and nitrite levels, and was validated against an independent set of experiments with the same biomass. In aerobic ammonium oxidation experiments the nitrifier denitrification and heterotrophic denitrification estimated pathway contributions increased at high nitrite and low oxygen concentrations; while the nitrifier nitrification pathway showed the largest contribution at high dissolved oxygen levels. The uncertainty of N2O emissions during model calibration is commonly overlooked, which limits the confidence of model-based mitigation strategies. Here we show that the precision of the estimated parameters resulted in a low uncertainty of the N2O emission factors during aerobic ammonium oxidation at DO ≈ 2.0 mg/L (1.2 ± 0.1%) and DO ≈ 0.5 mg/L (4.6 ± 0.6%).

KW - Nitrous oxide

KW - activated sludge

KW - Modelling

KW - Uncertainty

KW - Respirometry

U2 - 10.1016/j.cej.2019.122311

DO - 10.1016/j.cej.2019.122311

M3 - Journal article

VL - 379

JO - Biochemical Engineering Journal

JF - Biochemical Engineering Journal

SN - 1369-703X

M1 - 122311

ER -