Complex multi-pathways of N2O production across macroscopic and microscopic spatial scales in a full-scale IFAS-CANON system treating sludge digestion supernatant.

Λεπτομέρειες βιβλιογραφικής εγγραφής
Τίτλος:	Complex multi-pathways of N2O production across macroscopic and microscopic spatial scales in a full-scale IFAS-CANON system treating sludge digestion supernatant.
Συγγραφείς:	Cao X; Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100124, China., Liu X; Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100124, China. Electronic address: lxhfei@163.com., Huang S; National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing, 100124, China., Zhang N; Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100124, China., Lyu J; National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing, 100124, China., Wang B; Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100124, China., Fan B; Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100124, China., Yang Q; National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing, 100124, China.
Πηγή:	Water research [Water Res] 2026 Oct 15; Vol. 305, pp. 126540. Date of Electronic Publication: 2026 Jul 20.
Τύπος έκδοσης:	Journal Article
Γλώσσα:	English
Στοιχεία περιοδικού:	Publisher: Pergamon Press Country of Publication: England NLM ID: 0105072 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1879-2448 (Electronic) Linking ISSN: 00431354 NLM ISO Abbreviation: Water Res Subsets: MEDLINE
Imprint Name(s):	Original Publication: Oxford, Pergamon Press.
Ιατρικοί όροι (MeSH):	Sewage/microbiology , Nitrous Oxide/metabolism , Waste Disposal, Fluid*/methods, Bioreactors/microbiology ; Bacteria/metabolism ; Denitrification ; Nitrites ; Biofilms
Περίληψη:	Completely autotrophic nitrogen removal over nitrite (CANON) is widely implemented for treating high-ammonium wastewater. However, nitrous oxide (N2O) emissions may offset its climate benefits, and pathway-level evidence from full-scale systems remains scarce. Here, N2O production, transformation, and underlying pathways were investigated in a full-scale integrated fixed-film activated sludge (IFAS)-CANON system treating sludge digestion supernatant using in situ monitoring, batch tests, biofilm microelectrode profiling, and stable isotope analysis. The N2O emission factor of the full-scale system reached 1.59 ± 0.50% of the total nitrogen removed. Despite similar microbial community structures across different locations, N2O production and associated pathways varied spatially. Ammonia-oxidizing bacteria (AOB)-enriched activated sludge and the biofilm outer layer were identified as the main N2O-producing zones. Driven by the complex wastewater matrix, both biotic and abiotic pathways contributed to N2O production, with biotic processes dominating. Biotic pathways mainly included AOB denitrification and hydroxylamine (NH2OH) oxidation, and heterotrophic denitrification also contributed due to limited biodegradable carbon and low denitrifying community diversity. For abiotic N2O production, NH2OH oxidation by HNO2 was a potentially important pathway. Nitrite accumulation was the key driver across all critical pathways. Correspondingly, in the full-scale system, N2O production was significantly higher at locations where NO2⁻-N concentrations exceeded 25 mg/L than at downstream locations. These findings provide process-level mechanistic insights and identify key targets for reducing N2O emissions in full-scale IFAS-CANON systems. (Copyright © 2026 Elsevier Ltd. All rights reserved.)
Competing Interests:	Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Contributed Indexing:	Keywords: Abiotic; Biotic; IFAS-CANON; N(2)O; Nitrite accumulation; Pathway
Substance Nomenclature:	0 (Sewage) K50XQU1029 (Nitrous Oxide) 0 (Nitrites)
Entry Date(s):	Date Created: 20260723 Date Completed: 20260909 Latest Revision: 20260909
Update Code:	20260909
DOI:	10.1016/j.watres.2026.126540
PMID:	42492214
Βάση Δεδομένων:	MEDLINE

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