Biotransformation of Benzotriazoles: Insights from Transformation Product Identification and Compound-Specific Isotope Analysis

• Published in: Environmental science & technology Vol. 48; no. 8; pp. 4435 - 4443
• Main Authors: Huntscha, Sebastian, Hofstetter, Thomas B, Schymanski, Emma L, Spahr, Stephanie, Hollender, Juliane
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.04.2014
• Subjects: Applied sciences; Batch Cell Culture Techniques; Biodegradation; Biodegradation, Environmental; Biological and medical sciences; Biological treatment of waters; Bioreactors; Biotechnology; Biotransformation; Carbon Isotopes; Chemical compounds; Chemical Fractionation; Effluents; Environment and pollution; Exact sciences and technology; Fractionation; Fundamental and applied biological sciences. Psychology; General purification processes; Industrial applications and implications. Economical aspects; Isotope Labeling - methods; Isotopes; Mass spectrometry; Nitrogen Isotopes; Oxidation; Pollution; Sewage - chemistry; Sewage - microbiology; Sludge; Time Factors; Triazoles - metabolism; Wastewaters; Water treatment; Water treatment and pollution; Isotopic analysis; Activated sludge; Benzotriazole derivatives; Water treatment; Chemical analysis; Metabolite; Metabolic pathway; Corrosion inhibitor; Biological purification; Biotransformation; Stable isotopes; Qualitative analysis; Waste water purification; Organic compounds
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es405694z

Benzotriazoles are widely used domestic and industrial corrosion inhibitors and have become omnipresent organic micropollutants in the aquatic environment. Here, the range of aerobic biological degradation mechanisms of benzotriazoles in activated sludge was investigated. Degradation pathways were elucidated by identifying transient and persistent transformation products in batch experiments using liquid chromatography–high-resolution tandem mass spectrometry (LC-HR-MS/MS). In addition, initial reactions were studied using compound-specific isotope analysis (CSIA). Biodegradation half-lives of 1.0 days for 1H-benzotriazole, 8.5 days for 4-methyl-1H-benzotriazole, and 0.9 days for 5-methyl-1H-benzotriazole with activated sludge confirmed their known partial persistence in conventional wastewater treatment. Major transformation products were identified as 4- and 5-hydroxy-1H-benzotriazole for the degradation of 1H-benzotriazole, and 1H-benzotriazole-5-carboxylic acid for the degradation of 5-methyl-1H-benzotriazole. These transformation products were found in wastewater effluents, showing their environmental relevance. Many other candidate transformation products, tentatively identified by interpretation of HR-MS/MS spectra, showed the broad range of possible reaction pathways including oxidation, alkylation, hydroxylation and indicate the significance of cometabolic processes for micropollutant degradation in biological wastewater treatment in general. The combination of evidence from product analysis with the significant carbon and nitrogen isotope fractionation suggests that aromatic monohydroxylation is the predominant step during the biotransformation of 1H-benzotriazole.