Understanding N2O formation mechanisms through sensitivity analyses using a plant-wide benchmark simulation model

Riccardo Boiocchi, Krist Gernaey, Gürkan Sin

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

In the present work, sensitivity analyses are performed on a plant-wide model incorporating the typical treatment unit of a full-scale wastewater treatment plant and N2O production and emission dynamics. The influence of operating temperatureis investigated. The results are exploited to identify the biological mechanisms responsible for N2O emissions,TN removal efficiency, competition for oxygen among the different microbial groups and the trade-off between oxygen consumption and effluent nitrogen loading. It was found that N2O emissions are triggered by poor oxygenation levels which cause an imbalance in the activity of NOB over the activity of AOB. As a matter of fact this imbalance leads to nitrite accumulation which in turn triggers AOB denitrification. This is particularly true at high temperatures, due to higher difference between AOB and NOB specific growth rates. At the same time, too high oxygen availability is found to inhibit heterotrophic denitrification, leading to incomplete reduction of nitrogen oxides and thereby to an accumulation of nitrous oxide. High oxygen supply is also found to worsen effluent quality via inhibition of heterotrophic denitrification. Low temperatures have shown to drastically limit aerobic AOB activity, thus compromising effluent quality. Finally, the organic biodegradable carbon surplus leaving the anoxic zone is identified to slow down NOB activity via oxygen competition with heterotrophs in the aerobic zone. With regard to the control strategy for the minimization of N2O emissions,the ratio between nitrate produced and ammonium consumed in an aerobic zone should be considered as candidate controlled variable to check whether nitrification is complete or nitrites are building up. Oxygen availability should be regulated according to the measured controlled variable.
Original languageEnglish
JournalChemical Engineering Journal
Volume317
Pages (from-to) 935–951
ISSN1385-8947
DOIs
Publication statusPublished - 2017

Keywords

  • Nitrous oxide
  • Sensitivity analysis
  • Morris screening
  • Monte Carlo
  • Wastewater

Cite this

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title = "Understanding N2O formation mechanisms through sensitivity analyses using a plant-wide benchmark simulation model",
abstract = "In the present work, sensitivity analyses are performed on a plant-wide model incorporating the typical treatment unit of a full-scale wastewater treatment plant and N2O production and emission dynamics. The influence of operating temperatureis investigated. The results are exploited to identify the biological mechanisms responsible for N2O emissions,TN removal efficiency, competition for oxygen among the different microbial groups and the trade-off between oxygen consumption and effluent nitrogen loading. It was found that N2O emissions are triggered by poor oxygenation levels which cause an imbalance in the activity of NOB over the activity of AOB. As a matter of fact this imbalance leads to nitrite accumulation which in turn triggers AOB denitrification. This is particularly true at high temperatures, due to higher difference between AOB and NOB specific growth rates. At the same time, too high oxygen availability is found to inhibit heterotrophic denitrification, leading to incomplete reduction of nitrogen oxides and thereby to an accumulation of nitrous oxide. High oxygen supply is also found to worsen effluent quality via inhibition of heterotrophic denitrification. Low temperatures have shown to drastically limit aerobic AOB activity, thus compromising effluent quality. Finally, the organic biodegradable carbon surplus leaving the anoxic zone is identified to slow down NOB activity via oxygen competition with heterotrophs in the aerobic zone. With regard to the control strategy for the minimization of N2O emissions,the ratio between nitrate produced and ammonium consumed in an aerobic zone should be considered as candidate controlled variable to check whether nitrification is complete or nitrites are building up. Oxygen availability should be regulated according to the measured controlled variable.",
keywords = "Nitrous oxide, Sensitivity analysis, Morris screening, Monte Carlo, Wastewater",
author = "Riccardo Boiocchi and Krist Gernaey and G{\"u}rkan Sin",
year = "2017",
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language = "English",
volume = "317",
pages = "935–951",
journal = "Chemical Engineering Journal",
issn = "1385-8947",
publisher = "Elsevier",

}

Understanding N2O formation mechanisms through sensitivity analyses using a plant-wide benchmark simulation model. / Boiocchi, Riccardo; Gernaey, Krist; Sin, Gürkan.

In: Chemical Engineering Journal, Vol. 317, 2017, p. 935–951.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Understanding N2O formation mechanisms through sensitivity analyses using a plant-wide benchmark simulation model

AU - Boiocchi, Riccardo

AU - Gernaey, Krist

AU - Sin, Gürkan

PY - 2017

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N2 - In the present work, sensitivity analyses are performed on a plant-wide model incorporating the typical treatment unit of a full-scale wastewater treatment plant and N2O production and emission dynamics. The influence of operating temperatureis investigated. The results are exploited to identify the biological mechanisms responsible for N2O emissions,TN removal efficiency, competition for oxygen among the different microbial groups and the trade-off between oxygen consumption and effluent nitrogen loading. It was found that N2O emissions are triggered by poor oxygenation levels which cause an imbalance in the activity of NOB over the activity of AOB. As a matter of fact this imbalance leads to nitrite accumulation which in turn triggers AOB denitrification. This is particularly true at high temperatures, due to higher difference between AOB and NOB specific growth rates. At the same time, too high oxygen availability is found to inhibit heterotrophic denitrification, leading to incomplete reduction of nitrogen oxides and thereby to an accumulation of nitrous oxide. High oxygen supply is also found to worsen effluent quality via inhibition of heterotrophic denitrification. Low temperatures have shown to drastically limit aerobic AOB activity, thus compromising effluent quality. Finally, the organic biodegradable carbon surplus leaving the anoxic zone is identified to slow down NOB activity via oxygen competition with heterotrophs in the aerobic zone. With regard to the control strategy for the minimization of N2O emissions,the ratio between nitrate produced and ammonium consumed in an aerobic zone should be considered as candidate controlled variable to check whether nitrification is complete or nitrites are building up. Oxygen availability should be regulated according to the measured controlled variable.

AB - In the present work, sensitivity analyses are performed on a plant-wide model incorporating the typical treatment unit of a full-scale wastewater treatment plant and N2O production and emission dynamics. The influence of operating temperatureis investigated. The results are exploited to identify the biological mechanisms responsible for N2O emissions,TN removal efficiency, competition for oxygen among the different microbial groups and the trade-off between oxygen consumption and effluent nitrogen loading. It was found that N2O emissions are triggered by poor oxygenation levels which cause an imbalance in the activity of NOB over the activity of AOB. As a matter of fact this imbalance leads to nitrite accumulation which in turn triggers AOB denitrification. This is particularly true at high temperatures, due to higher difference between AOB and NOB specific growth rates. At the same time, too high oxygen availability is found to inhibit heterotrophic denitrification, leading to incomplete reduction of nitrogen oxides and thereby to an accumulation of nitrous oxide. High oxygen supply is also found to worsen effluent quality via inhibition of heterotrophic denitrification. Low temperatures have shown to drastically limit aerobic AOB activity, thus compromising effluent quality. Finally, the organic biodegradable carbon surplus leaving the anoxic zone is identified to slow down NOB activity via oxygen competition with heterotrophs in the aerobic zone. With regard to the control strategy for the minimization of N2O emissions,the ratio between nitrate produced and ammonium consumed in an aerobic zone should be considered as candidate controlled variable to check whether nitrification is complete or nitrites are building up. Oxygen availability should be regulated according to the measured controlled variable.

KW - Nitrous oxide

KW - Sensitivity analysis

KW - Morris screening

KW - Monte Carlo

KW - Wastewater

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SN - 1385-8947

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