Nitric oxide reactivity accounts for N-nitroso-ciprofloxacin formation under nitrate-reducing conditions

WATER RESEARCH

卷:185

Article

Brienza, Monica¹  Manasfi, Rayana¹  Sauvetre, Andres¹  Chiron, Serge¹ 

[1] Montpellier Univ, UMR HydroSci Montpellier, IRD, 15 Ave Charles Flahault, F-34093 Montpellier 5, France

关键词: N-nitrosamine;    N-nitroso-ciprofloxacin;    Nitric oxide;    Activated sludge;    Biodegradation;   

DOI  :  10.1016/j.watres.2020.116293

来源: Elsevier

【 摘 要 】

The formation of N-nitroso-ciprofloxacin (CIP) was investigated both in wastewater treatment plants including nitrification/denitrification stages and in sludge slurry experiments under denitrifying conditions. The analysis of biological wastewater treatment plant effluents by Kendrick mass defect analysis and liquid chromatography - high resolution - mass spectrometry (LC-HRMS) revealed the occurrence of N-nitroso-CIP and N-nitroso-hydrochlorothiazide at concentration levels of 34 +/- 3 ng/L and 71 +/- 6 ng/L, respectively. In laboratory experiments and dark conditions, produced N-nitroso-CIP concentrations reached a plateau during the course of biodegradation experiments. A mass balance was achieved after identification and quantification of several transformation products by LC-HRMS. N-nitroso-CIP accounted for 14.3% of the initial CIP concentration (20 mu g/L) and accumulated against time. The use of 4,5-diaminofluorescein diacetate and superoxide dismutase as scavengers for in situ production of nitric oxide and superoxide radical anion respectively, revealed that the mechanisms of formation of N-nitroso-CIP likely involved a nitrosation pathway through the formation of peroxynitrite and another one through codenitrification processes, even though the former one appeared to be prevalent. This work extended the possible sources of N-nitrosamines by including a formation pathway relying on nitric oxide reactivity with secondary amines under activated sludge treatment. (c) 2020 Elsevier Ltd. All rights reserved.

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