Unwanted mainstream nitritation–denitritation causing massive N2O emissions in a continuous activated sludge process

Nitrous oxide emissions can contribute significantly to the carbon footprint of municipal wastewater treatment plants even though emissions from conventional nitrogen removal processes are assumed to be moderate. An increased risk for high emissions can occur in connection with process disturbances...

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Autores principales:	A. Kuokkanen, K. Blomberg, A. Mikola, M. Heinonen
Formato:	article
Lenguaje:	EN
Publicado:	IWA Publishing 2021
Materias:	activated sludge process ghg n2o nitritation–denitritation nitrous oxide no2− Environmental technology. Sanitary engineering TD1-1066
Acceso en línea:	https://doaj.org/article/9d699d7b663f4b37906e91c88fe9ef06
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spelling	oai:doaj.org-article:9d699d7b663f4b37906e91c88fe9ef062021-11-06T11:01:48ZUnwanted mainstream nitritation–denitritation causing massive N2O emissions in a continuous activated sludge process0273-12231996-973210.2166/wst.2021.127https://doaj.org/article/9d699d7b663f4b37906e91c88fe9ef062021-05-01T00:00:00Zhttp://wst.iwaponline.com/content/83/9/2207https://doaj.org/toc/0273-1223https://doaj.org/toc/1996-9732Nitrous oxide emissions can contribute significantly to the carbon footprint of municipal wastewater treatment plants even though emissions from conventional nitrogen removal processes are assumed to be moderate. An increased risk for high emissions can occur in connection with process disturbances and nitrite (NO2−) accumulation. This work describes the findings at a large municipal wastewater treatment plant where the levels of NO2− in the activated sludge process effluent were spontaneously and strongly increased on several activated sludge lines which was suspected to be due to shortcut nitrogen removal that stabilized for several months. The high NO2− levels were linked to a dramatic increase in nitrous oxide (N2O) emissions. As much as over 20% of the daily influent nitrogen load was emitted as N2O. These observations indicate that highly increased NO2− levels can occur in conventional activated sludge processes and result in high nitrous oxide emissions. They also raise questions concerning the risk of increased greenhouse gas (GHG) emissions of the nitritation–denitritation processes – although the uncontrolled nature of the event described here must be taken into consideration – and underline the importance of continuous monitoring and control of N2O emissions. HIGHLIGHTS NO2− can play a significant role in N2O emissions also in conventional activated sludge processes.; Variations in NO2− levels can explain poorer than expected negative correlation between total nitrogen removal and N2O.; Nitritation-denitritation can stabilize for a long period also in conditions that do not typically promote it.; Monitoring N2O emissions is crucial in operating nitritation–denitritation processes.;A. KuokkanenK. BlombergA. MikolaM. HeinonenIWA Publishingarticleactivated sludge processghgn2onitritation–denitritationnitrous oxideno2−Environmental technology. Sanitary engineeringTD1-1066ENWater Science and Technology, Vol 83, Iss 9, Pp 2207-2217 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	activated sludge process ghg n2o nitritation–denitritation nitrous oxide no2− Environmental technology. Sanitary engineering TD1-1066
spellingShingle	activated sludge process ghg n2o nitritation–denitritation nitrous oxide no2− Environmental technology. Sanitary engineering TD1-1066 A. Kuokkanen K. Blomberg A. Mikola M. Heinonen Unwanted mainstream nitritation–denitritation causing massive N2O emissions in a continuous activated sludge process
description	Nitrous oxide emissions can contribute significantly to the carbon footprint of municipal wastewater treatment plants even though emissions from conventional nitrogen removal processes are assumed to be moderate. An increased risk for high emissions can occur in connection with process disturbances and nitrite (NO2−) accumulation. This work describes the findings at a large municipal wastewater treatment plant where the levels of NO2− in the activated sludge process effluent were spontaneously and strongly increased on several activated sludge lines which was suspected to be due to shortcut nitrogen removal that stabilized for several months. The high NO2− levels were linked to a dramatic increase in nitrous oxide (N2O) emissions. As much as over 20% of the daily influent nitrogen load was emitted as N2O. These observations indicate that highly increased NO2− levels can occur in conventional activated sludge processes and result in high nitrous oxide emissions. They also raise questions concerning the risk of increased greenhouse gas (GHG) emissions of the nitritation–denitritation processes – although the uncontrolled nature of the event described here must be taken into consideration – and underline the importance of continuous monitoring and control of N2O emissions. HIGHLIGHTS NO2− can play a significant role in N2O emissions also in conventional activated sludge processes.; Variations in NO2− levels can explain poorer than expected negative correlation between total nitrogen removal and N2O.; Nitritation-denitritation can stabilize for a long period also in conditions that do not typically promote it.; Monitoring N2O emissions is crucial in operating nitritation–denitritation processes.;
format	article
author	A. Kuokkanen K. Blomberg A. Mikola M. Heinonen
author_facet	A. Kuokkanen K. Blomberg A. Mikola M. Heinonen
author_sort	A. Kuokkanen
title	Unwanted mainstream nitritation–denitritation causing massive N2O emissions in a continuous activated sludge process
title_short	Unwanted mainstream nitritation–denitritation causing massive N2O emissions in a continuous activated sludge process
title_full	Unwanted mainstream nitritation–denitritation causing massive N2O emissions in a continuous activated sludge process
title_fullStr	Unwanted mainstream nitritation–denitritation causing massive N2O emissions in a continuous activated sludge process
title_full_unstemmed	Unwanted mainstream nitritation–denitritation causing massive N2O emissions in a continuous activated sludge process
title_sort	unwanted mainstream nitritation–denitritation causing massive n2o emissions in a continuous activated sludge process
publisher	IWA Publishing
publishDate	2021
url	https://doaj.org/article/9d699d7b663f4b37906e91c88fe9ef06
work_keys_str_mv	AT akuokkanen unwantedmainstreamnitritationdenitritationcausingmassiven2oemissionsinacontinuousactivatedsludgeprocess AT kblomberg unwantedmainstreamnitritationdenitritationcausingmassiven2oemissionsinacontinuousactivatedsludgeprocess AT amikola unwantedmainstreamnitritationdenitritationcausingmassiven2oemissionsinacontinuousactivatedsludgeprocess AT mheinonen unwantedmainstreamnitritationdenitritationcausingmassiven2oemissionsinacontinuousactivatedsludgeprocess
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Unwanted mainstream nitritation–denitritation causing massive N2O emissions in a continuous activated sludge process

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