Nitrous oxide production pathways during biological nitrogen removal in wastewater treatment

Chun Ma

Nitrous oxide production pathways during biological nitrogen removal in wastewater treatment

Chun Ma

Publikation: Afhandling › Ph.d.-afhandling

Abstract

Lattergas (N2O) er en uønsket gas som bliver dannet under biologisk fjernelse af kvælstof i spildevand. Det er en kraftig drivhusgas med potentiale for stratosfærisk ozon-nedbrydning. N2O-emission fra biologisk kvælstoffjernelse fra spildevandsrensning kan bidrage væsentligt til det ækvivalente kuldioxid (CO2) footprint. Størstedelen af N2O-produktionen stammer fra ammonium oxiderende bakterier (AOB) og denitrificerende bakterier via nitrifier nitrifikation (NN), nitrifier denitrifikation (ND) og heterotrof denitrifikation (HD) pathways. Der har været mange bestræbelser på at karakterisere produktionen af N2O i spildevandsrensnings-anlæg, alligevel er den grundlæggende viden omkring de forskellige pathways og kontrollen af N2O-produktion begrænset. En af de store udfordringer er vanskeligheder med at skelne de forskellige pathways i de komplekse mikrobielle samfund. I denne afhandling, er batch-inkubations studier, Labskala undersøgelser og fuldskala overvågning af dynamikken i N2O-produktion kombineret, og 15N/18O stabil isotop-mærkning er brugt til at give en bedre forståelse for N2O-produktions mekanismer.

I Kapitel 2 blev N2O-produktions pathways fra nitritation-nammox undersøgt i korte inkubationermed 15N stabil isotop-mærkning. Effekten af opløst ilt (DO), ammonium (NH4+) og nitrit (NO2-) på N2O-produktion blev også undersøgt. Når NO2 --koncentrationen var lav og ved en koncentration af DO på 0,2 mg L-1 var NN den dominerende pathway for produktion af N2O. Samtidig tilstedeværelse af høj NO2 - og lav DO vil inducere ND.

N2O-dynamikken i en Labskala nitritation reaktor blev undersøgt ved hjælp af online overvågning af opløst N2O kombineret med 15N stabil isotop-mærkning. Hensigten var at afdække N2Oproduktionsmekanismerne (beskrevet i Kapitel 3). ND var ansvarlig for størstedelen af N2Oproduktionen.

Kapitel 4 fokuserer på fuldskala anlæg. En ny 15N/18O dobbelt mærkningsmetode blev etableret for at studere dynamikken i N2O-produktion pathways i et fuldskala aktiveret slam anlæg. Resultaterne viste, at den oxiske fase var den største N2O-kilde med 5-10 gange større akkumulering end i den anoxiske fase.

Studierne viste, at 15N/18O stabil isotop-mærkning er en robust metode til skelne mellem de forskellige
N2O-produktions pathways i anlæg der benytter biologisk fjernelse af kvælstof. Endvidere kan
metoden bidrage til udvikling af operationelle strategier der minimerer N2O-emission. Alle tre pathways (NN, ND, og HD) var aktive i kvælstof fjernelses-processer, hvor de hver reagerede forskelligt på ændringer i de operationelle forhold. NN kan være en betydelig kilde til N2O i nitritationanammox og aktiveret slam-anlæg og kan bidrage med op til ~ 100% af den samlede N2O-produktion. ND er dog den største kilde til N2O i nitritation, primært på grund af høje NO2--koncentrationer samtidig med lave koncentrationer af DO. HD var en mindre kilde til N2O under iltede forhold i alle testede kvælstof fjernelses-processer, mens N2O-produktionen blev forstærket når DO var fraværende eller når biologisk nedbrydeligt organisk kulstof (COD) var til stede. Det relative bidrag fra NN og ND til den samlede N2O-produktion blev hovedsageligt afgjort af DO-niveauet og NO2- koncentrationen.

Originalsprog	Engelsk
Bevilgende institution	Syddansk Universitet
Vejledere/rådgivere	Thamdrup, Bo, Vejleder Jensen, Marlene Mark, Vejleder, Ekstern person Smets, Barth F., Vejleder, Ekstern person
Udgiver	Syddansk Universitet. Det Naturvidenskabelige Fakultet
Status	Udgivet - dec. 2016

SDU link

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2 Tidsskriftartikel

Low nitrous oxide production through nitrifier-denitrification in intermittent-feed high-rate nitritation reactors
Su, Q., Ma, C., Domingo Felez, C., Kiil, A. S., Thamdrup, B., Jensen, M. M. & Smets, B. F., 2017, I: Water Research. 123, s. 429-438
Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › peer review
Pathways and controls of N₂O production in nitritation-anammox biomass
Ma, C., Jensen, M. M., Smets, B. F. & Thamdrup, B., 15. aug. 2017, I: Environmental Science & Technology. 51, 16, s. 8981-8991
Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › peer review

Citationsformater

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title = "Nitrous oxide production pathways during biological nitrogen removal in wastewater treatment",

abstract = "Nitrous oxide (N2O) is an unwanted byproduct from biological nitrogen removal in wastewater treatment, because it is a strong green house gas and major stratospheric ozone depletion substance. N2O emissions from biological nitrogen removal can contribute substantially to the carbon dioxide (CO2)-equivalent footprint of wastewater treatment. The majority of these N2O are produced by ammonia oxidizing bacteria (AOB) and denitrifiers via nitrifier nitrification (NN), nitrifier denitrification (ND), and heterotrophic denitrification (HD) pathways. Many efforts have been done to characterize the production of N2O in wastewater treatment system. However, the fundamental knowledge about pathways and controls of N2O production is limited, and mainly challenged by difficulties in distinguishing these different pathways in a complex microbial community. In this thesis, batch incubation studies, lab-scale investigations and full-scale monitoring of the dynamics of N2O production are combined with the 15N/18O stable isotope labeling approach to provide a better understanding of N2O production mechanisms.In Chapter 2 pathways of N2O production and their dependence on environmental parameters (DO, NO2 - and NH4 +) in nitritation-anammox biomass were investigated in short-term incubations. Under low NO2 - condition, NN was the dominant production pathway of N2O at 0.2 mg L-1 DO. However, ND was induced by external NO2 - addition and became as major N2O production pathway with 0.7 mM NO2 - addition.Dynamics of N2O in a lab-scale partial nitritation reactor was studied by online dissolved N2O monitoring combined with 15N stable isotope labeling (apply 15NH4 +/ 15NO2 - to the reactor) to reveal the mechanisms of N2O production (described in Chapter 3). N2O production was completely dominated by ND.Chapter 4 focuses on full-scale plant. A novel 15N/18O dual labeling method was established to study the dynamics of N2O production pathways in a full-scale activated sludge plant. The results showed that the oxic phase was the major source of N2O production with more than 5 times higher accumulation rates than in the anoxic phase. NN and ND contributed roughly equal at 3 mg L-1 DO, while ND was the dominante source at 1mg L-1 DO.The studies demonstrated that 15N/18O stable isotope labelling is a robust approach to distinguish different N2O production pathways in biological nitrogen removal plants, and it can contribute to the development of operational strategies to minimize N2O emissions. All three pathways (NN, ND, and HD) were active in nitrogen removal processes, each responding differently to changes in the operational conditions. NN can be a significant N2O source in nitritation-anammox and activated sludge system. It can contribute with up to ~100% of the total N2O production. However, ND is the predominate source of N2O in the partial nitritation process, due to high NO2 - concentrations together with low concentrations of DO. HD was a minor source of N2O under oxic conditions in all tested nitrogen removal processes, while promoted when DO was absent or organic carbon was present. The relative importance of NN and ND to total N2O production was mainly determined by DO level and NO2 - concentration.",

author = "Chun Ma",

year = "2016",

month = dec,

language = "English",

publisher = "Syddansk Universitet. Det Naturvidenskabelige Fakultet",

address = "Denmark",

school = "SDU",

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T1 - Nitrous oxide production pathways during biological nitrogen removal in wastewater treatment

AU - Ma, Chun

PY - 2016/12

Y1 - 2016/12

N2 - Nitrous oxide (N2O) is an unwanted byproduct from biological nitrogen removal in wastewater treatment, because it is a strong green house gas and major stratospheric ozone depletion substance. N2O emissions from biological nitrogen removal can contribute substantially to the carbon dioxide (CO2)-equivalent footprint of wastewater treatment. The majority of these N2O are produced by ammonia oxidizing bacteria (AOB) and denitrifiers via nitrifier nitrification (NN), nitrifier denitrification (ND), and heterotrophic denitrification (HD) pathways. Many efforts have been done to characterize the production of N2O in wastewater treatment system. However, the fundamental knowledge about pathways and controls of N2O production is limited, and mainly challenged by difficulties in distinguishing these different pathways in a complex microbial community. In this thesis, batch incubation studies, lab-scale investigations and full-scale monitoring of the dynamics of N2O production are combined with the 15N/18O stable isotope labeling approach to provide a better understanding of N2O production mechanisms.In Chapter 2 pathways of N2O production and their dependence on environmental parameters (DO, NO2 - and NH4 +) in nitritation-anammox biomass were investigated in short-term incubations. Under low NO2 - condition, NN was the dominant production pathway of N2O at 0.2 mg L-1 DO. However, ND was induced by external NO2 - addition and became as major N2O production pathway with 0.7 mM NO2 - addition.Dynamics of N2O in a lab-scale partial nitritation reactor was studied by online dissolved N2O monitoring combined with 15N stable isotope labeling (apply 15NH4 +/ 15NO2 - to the reactor) to reveal the mechanisms of N2O production (described in Chapter 3). N2O production was completely dominated by ND.Chapter 4 focuses on full-scale plant. A novel 15N/18O dual labeling method was established to study the dynamics of N2O production pathways in a full-scale activated sludge plant. The results showed that the oxic phase was the major source of N2O production with more than 5 times higher accumulation rates than in the anoxic phase. NN and ND contributed roughly equal at 3 mg L-1 DO, while ND was the dominante source at 1mg L-1 DO.The studies demonstrated that 15N/18O stable isotope labelling is a robust approach to distinguish different N2O production pathways in biological nitrogen removal plants, and it can contribute to the development of operational strategies to minimize N2O emissions. All three pathways (NN, ND, and HD) were active in nitrogen removal processes, each responding differently to changes in the operational conditions. NN can be a significant N2O source in nitritation-anammox and activated sludge system. It can contribute with up to ~100% of the total N2O production. However, ND is the predominate source of N2O in the partial nitritation process, due to high NO2 - concentrations together with low concentrations of DO. HD was a minor source of N2O under oxic conditions in all tested nitrogen removal processes, while promoted when DO was absent or organic carbon was present. The relative importance of NN and ND to total N2O production was mainly determined by DO level and NO2 - concentration.

AB - Nitrous oxide (N2O) is an unwanted byproduct from biological nitrogen removal in wastewater treatment, because it is a strong green house gas and major stratospheric ozone depletion substance. N2O emissions from biological nitrogen removal can contribute substantially to the carbon dioxide (CO2)-equivalent footprint of wastewater treatment. The majority of these N2O are produced by ammonia oxidizing bacteria (AOB) and denitrifiers via nitrifier nitrification (NN), nitrifier denitrification (ND), and heterotrophic denitrification (HD) pathways. Many efforts have been done to characterize the production of N2O in wastewater treatment system. However, the fundamental knowledge about pathways and controls of N2O production is limited, and mainly challenged by difficulties in distinguishing these different pathways in a complex microbial community. In this thesis, batch incubation studies, lab-scale investigations and full-scale monitoring of the dynamics of N2O production are combined with the 15N/18O stable isotope labeling approach to provide a better understanding of N2O production mechanisms.In Chapter 2 pathways of N2O production and their dependence on environmental parameters (DO, NO2 - and NH4 +) in nitritation-anammox biomass were investigated in short-term incubations. Under low NO2 - condition, NN was the dominant production pathway of N2O at 0.2 mg L-1 DO. However, ND was induced by external NO2 - addition and became as major N2O production pathway with 0.7 mM NO2 - addition.Dynamics of N2O in a lab-scale partial nitritation reactor was studied by online dissolved N2O monitoring combined with 15N stable isotope labeling (apply 15NH4 +/ 15NO2 - to the reactor) to reveal the mechanisms of N2O production (described in Chapter 3). N2O production was completely dominated by ND.Chapter 4 focuses on full-scale plant. A novel 15N/18O dual labeling method was established to study the dynamics of N2O production pathways in a full-scale activated sludge plant. The results showed that the oxic phase was the major source of N2O production with more than 5 times higher accumulation rates than in the anoxic phase. NN and ND contributed roughly equal at 3 mg L-1 DO, while ND was the dominante source at 1mg L-1 DO.The studies demonstrated that 15N/18O stable isotope labelling is a robust approach to distinguish different N2O production pathways in biological nitrogen removal plants, and it can contribute to the development of operational strategies to minimize N2O emissions. All three pathways (NN, ND, and HD) were active in nitrogen removal processes, each responding differently to changes in the operational conditions. NN can be a significant N2O source in nitritation-anammox and activated sludge system. It can contribute with up to ~100% of the total N2O production. However, ND is the predominate source of N2O in the partial nitritation process, due to high NO2 - concentrations together with low concentrations of DO. HD was a minor source of N2O under oxic conditions in all tested nitrogen removal processes, while promoted when DO was absent or organic carbon was present. The relative importance of NN and ND to total N2O production was mainly determined by DO level and NO2 - concentration.

M3 - Ph.D. thesis

PB - Syddansk Universitet. Det Naturvidenskabelige Fakultet

ER -

Nitrous oxide production pathways during biological nitrogen removal in wastewater treatment

Abstract

SDU link

Fingeraftryk

Relaterede publikationer

Low nitrous oxide production through nitrifier-denitrification in intermittent-feed high-rate nitritation reactors

Pathways and controls of N2O production in nitritation-anammox biomass

Citationsformater

Pathways and controls of N₂O production in nitritation-anammox biomass