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Updated: Jun 17, 2026

Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O
Published on: October 7, 2020
Nitration processes of acetaminophen in nitrifying activated sludge.
Serge Chiron1, Elena Gomez, Hélène Fenet
1UMR 5569 'Hydrosciences Montpellier' University of Montpellier I, 15 Avenue Ch. Flahault, BP 14491, 34093 Montpellier cedex 5, France. serge.chiron@univ-provence.fr
Acetaminophen (APAP) can be nitrated in wastewater treatment plants, forming potentially harmful compounds. Nitrifying bacteria likely contribute to this process via nitric oxide and superoxide anion.
Area of Science:
- Environmental Chemistry
- Microbiology
- Wastewater Treatment
Background:
- Acetaminophen (APAP) is a common pharmaceutical pollutant.
- Wastewater treatment plants (WWTPs) are key sites for pollutant transformation.
- Nitrification is a critical step in nitrogen removal in WWTPs.
Purpose of the Study:
- To quantify acetaminophen (APAP) nitration in nitrifying activated sludge.
- To propose a reaction mechanism for APAP nitration during nitrification.
- To assess the ecotoxicological relevance of nitrated APAP derivatives.
Main Methods:
- Field studies at a full-scale WWTP with nitrogen removal.
- Batch experiments using nitrifying activated sludge.
- In vitro assays to investigate reaction pathways.
Main Results:
- 3-nitro-APAP and 3-chloro-5-nitro-APAP detected in WWTP effluents (50-300 ng/L).
- Nitrifying bacteria suggested to play a role in APAP nitration via reactive nitrogen species.
- Nitric oxide (*NO) and superoxide anion formation of peroxynitrite identified as likely nitration pathway.
Conclusions:
- APAP nitration occurs in WWTPs, with nitrating bacteria potentially involved.
- Nitrated APAP derivatives pose ecotoxicological risks.
- Further research needed to fully understand APAP transformation and its environmental impact.
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