N2O emission in full-scale wastewater treatment: Proposing a refined monitoring strategy

Wenzel Gruber; Kris Villez; Marco Kipf; Pascal Wunderlin; Hansruedi Siegrist; Liliane Vogt; Adriano Joss

doi:10.1016/j.scitotenv.2019.134157

N₂O emission in full-scale wastewater treatment: Proposing a refined monitoring strategy

Wenzel Gruber, Kris Villez, Marco Kipf, Pascal Wunderlin, Hansruedi Siegrist, Liliane Vogt, Adriano Joss

Research output: Contribution to journal › Article › peer-review

69 Scopus citations

Abstract

Nitrous oxide (N₂O) emissions from wastewater treatment contribute significantly to greenhouse gas emissions. They have been shown to exhibit a strong seasonal and daily profile in previously conducted monitoring campaigns. However, only two year-long online monitoring campaigns have been published to date. Based on three monitoring campaigns on three full-scale wastewater treatment plants (WWTPs) with different activated sludge configurations, each of which lasted at least one year, we propose a refined monitoring strategy for long-term emission monitoring with multiple flux chambers on open tanks. Our monitoring campaigns confirm that the N₂O emissions exhibited a strong seasonal profile and were substantial on all three plants (1–2.4% of the total nitrogen load). These results confirm that N₂O is the most important greenhouse gas emission from wastewater treatment. The temporal variation was more distinct than the spatial variation within aeration tanks. Nevertheless, multiple monitoring spots along a single lane are crucial to assess representative emission factors in flow-through systems. Sequencing batch reactor systems were shown to exhibit comparable emissions within one reactor but significant variation between parallel reactors. The results indicate that considerable emission differences between lanes are to be expected in cases of inhomogeneous loading and discontinuous feeding. For example, N₂O emission could be shown to depend on the amount of treated reject water: lanes without emitted <1% of the influent load, while parallel lanes emitted around 3%. In case of inhomogeneous loading, monitoring of multiple lanes is required. Our study enables robust planning of monitoring campaigns on WWTPs with open tanks. Extensive full-scale emission monitoring campaigns are important as a basis for reliable decisions about reducing the climate impact of wastewater treatment. More specifically, such data sets help us to define general emission factors for wastewater treatment plants and to construct and critically evaluate N₂O emission models.

Original language	English
Article number	134157
Journal	Science of the Total Environment
Volume	699
DOIs	https://doi.org/10.1016/j.scitotenv.2019.134157
State	Published - Jan 10 2020
Externally published	Yes

Funding

This study was financially supported by the EU Horizon 2020 Powerstep project ( GA 641661 ) and Eawag Discretionary Funds ( DF14/N2O analysis), the Swiss Federal Office for the Environment (FOEN), the Canton of Bern (AWA) , the Canton of Basel-Landschaft (AIB) , the Canton of Zurich (AWEL) , TBF + Partner AG Consulting Engineers , Holinger AG , Hunziker-Betatech AG , Alpha Wassertechnik AG , WWTP region Bern , WWTP region Bellinzona , WWTP ProRheno , WWTP REAL Luzern , WWTP Zurich-Werdhölzli , WWTP Worblental , Abwasserverband Altenrhein , Abwasserverband Morgental , Entsorgung St. Gallen . We are extremely grateful to Alexander Kleiner, Christoph Egli, Jörg Ringwald, Markus Hürlimann, Arne Zumbach, and Ueli Alder for making their plants available for monitoring campaigns. Special thanks go to Eberhard Morgenroth, Luzia von Känel and Daniel Braun for very helpful discussions, and to Simon Milligan for language revisions during the preparation of the manuscript. Furthermore, we want to thank Karin Rottermann and Sylvia Richter for their help with the physicochemical analyses of all samples and Luzia von Känel for the data management. This study was financially supported by the EU Horizon 2020 Powerstep project (GA 641661) and Eawag Discretionary Funds (DF14/N2O analysis), the Swiss Federal Office for the Environment (FOEN), the Canton of Bern (AWA), the Canton of Basel-Landschaft (AIB), the Canton of Zurich (AWEL), TBF + Partner AG Consulting Engineers, Holinger AG, Hunziker-Betatech AG, Alpha Wassertechnik AG, WWTP region Bern, WWTP region Bellinzona, WWTP ProRheno, WWTP REAL Luzern, WWTP Zurich-Werdh?lzli, WWTP Worblental, Abwasserverband Altenrhein, Abwasserverband Morgental, Entsorgung St. Gallen. We are extremely grateful to Alexander Kleiner, Christoph Egli, J?rg Ringwald, Markus H?rlimann, Arne Zumbach, and Ueli Alder for making their plants available for monitoring campaigns. Special thanks go to Eberhard Morgenroth, Luzia von K?nel and Daniel Braun for very helpful discussions, and to Simon Milligan for language revisions during the preparation of the manuscript. Furthermore, we want to thank Karin Rottermann and Sylvia Richter for their help with the physicochemical analyses of all samples and Luzia von K?nel for the data management.

Keywords

Activated sludge
Biological nitrogen removal
Greenhouse gases
Nitrous oxide
Wastewater treatment

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1016/j.scitotenv.2019.134157

Cite this

@article{011bd7f813bb4717bb42d32ee2cb656c,

title = "N2O emission in full-scale wastewater treatment: Proposing a refined monitoring strategy",

abstract = "Nitrous oxide (N2O) emissions from wastewater treatment contribute significantly to greenhouse gas emissions. They have been shown to exhibit a strong seasonal and daily profile in previously conducted monitoring campaigns. However, only two year-long online monitoring campaigns have been published to date. Based on three monitoring campaigns on three full-scale wastewater treatment plants (WWTPs) with different activated sludge configurations, each of which lasted at least one year, we propose a refined monitoring strategy for long-term emission monitoring with multiple flux chambers on open tanks. Our monitoring campaigns confirm that the N2O emissions exhibited a strong seasonal profile and were substantial on all three plants (1–2.4% of the total nitrogen load). These results confirm that N2O is the most important greenhouse gas emission from wastewater treatment. The temporal variation was more distinct than the spatial variation within aeration tanks. Nevertheless, multiple monitoring spots along a single lane are crucial to assess representative emission factors in flow-through systems. Sequencing batch reactor systems were shown to exhibit comparable emissions within one reactor but significant variation between parallel reactors. The results indicate that considerable emission differences between lanes are to be expected in cases of inhomogeneous loading and discontinuous feeding. For example, N2O emission could be shown to depend on the amount of treated reject water: lanes without emitted <1% of the influent load, while parallel lanes emitted around 3%. In case of inhomogeneous loading, monitoring of multiple lanes is required. Our study enables robust planning of monitoring campaigns on WWTPs with open tanks. Extensive full-scale emission monitoring campaigns are important as a basis for reliable decisions about reducing the climate impact of wastewater treatment. More specifically, such data sets help us to define general emission factors for wastewater treatment plants and to construct and critically evaluate N2O emission models.",

keywords = "Activated sludge, Biological nitrogen removal, Greenhouse gases, Nitrous oxide, Wastewater treatment",

author = "Wenzel Gruber and Kris Villez and Marco Kipf and Pascal Wunderlin and Hansruedi Siegrist and Liliane Vogt and Adriano Joss",

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year = "2020",

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doi = "10.1016/j.scitotenv.2019.134157",

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T2 - Proposing a refined monitoring strategy

AU - Gruber, Wenzel

AU - Villez, Kris

AU - Kipf, Marco

AU - Wunderlin, Pascal

AU - Siegrist, Hansruedi

AU - Vogt, Liliane

AU - Joss, Adriano

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N2 - Nitrous oxide (N2O) emissions from wastewater treatment contribute significantly to greenhouse gas emissions. They have been shown to exhibit a strong seasonal and daily profile in previously conducted monitoring campaigns. However, only two year-long online monitoring campaigns have been published to date. Based on three monitoring campaigns on three full-scale wastewater treatment plants (WWTPs) with different activated sludge configurations, each of which lasted at least one year, we propose a refined monitoring strategy for long-term emission monitoring with multiple flux chambers on open tanks. Our monitoring campaigns confirm that the N2O emissions exhibited a strong seasonal profile and were substantial on all three plants (1–2.4% of the total nitrogen load). These results confirm that N2O is the most important greenhouse gas emission from wastewater treatment. The temporal variation was more distinct than the spatial variation within aeration tanks. Nevertheless, multiple monitoring spots along a single lane are crucial to assess representative emission factors in flow-through systems. Sequencing batch reactor systems were shown to exhibit comparable emissions within one reactor but significant variation between parallel reactors. The results indicate that considerable emission differences between lanes are to be expected in cases of inhomogeneous loading and discontinuous feeding. For example, N2O emission could be shown to depend on the amount of treated reject water: lanes without emitted <1% of the influent load, while parallel lanes emitted around 3%. In case of inhomogeneous loading, monitoring of multiple lanes is required. Our study enables robust planning of monitoring campaigns on WWTPs with open tanks. Extensive full-scale emission monitoring campaigns are important as a basis for reliable decisions about reducing the climate impact of wastewater treatment. More specifically, such data sets help us to define general emission factors for wastewater treatment plants and to construct and critically evaluate N2O emission models.

AB - Nitrous oxide (N2O) emissions from wastewater treatment contribute significantly to greenhouse gas emissions. They have been shown to exhibit a strong seasonal and daily profile in previously conducted monitoring campaigns. However, only two year-long online monitoring campaigns have been published to date. Based on three monitoring campaigns on three full-scale wastewater treatment plants (WWTPs) with different activated sludge configurations, each of which lasted at least one year, we propose a refined monitoring strategy for long-term emission monitoring with multiple flux chambers on open tanks. Our monitoring campaigns confirm that the N2O emissions exhibited a strong seasonal profile and were substantial on all three plants (1–2.4% of the total nitrogen load). These results confirm that N2O is the most important greenhouse gas emission from wastewater treatment. The temporal variation was more distinct than the spatial variation within aeration tanks. Nevertheless, multiple monitoring spots along a single lane are crucial to assess representative emission factors in flow-through systems. Sequencing batch reactor systems were shown to exhibit comparable emissions within one reactor but significant variation between parallel reactors. The results indicate that considerable emission differences between lanes are to be expected in cases of inhomogeneous loading and discontinuous feeding. For example, N2O emission could be shown to depend on the amount of treated reject water: lanes without emitted <1% of the influent load, while parallel lanes emitted around 3%. In case of inhomogeneous loading, monitoring of multiple lanes is required. Our study enables robust planning of monitoring campaigns on WWTPs with open tanks. Extensive full-scale emission monitoring campaigns are important as a basis for reliable decisions about reducing the climate impact of wastewater treatment. More specifically, such data sets help us to define general emission factors for wastewater treatment plants and to construct and critically evaluate N2O emission models.

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