Mutual influence mechanism of nitrate and sulfamethoxazole on their biotransformation in poly (3-hydroxybutyrate-3-hydroxyvalerate) supported denitrification biofilter for a long-term operation

• Published in: Journal of environmental management Vol. 345; p. 118897
• Main Authors: Xu, Zhongshuo, Ze, Siwen, Chen, Xueting, Song, Xinshan, Wang, Yuhui
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-11-2023
• Subjects: Denitrification; Denitrification gene; Microbial community structure; Resistant gene; SMX biotransformation; Denitrification; SMX biotransformation; Resistant gene; Microbial community structure; Denitrification gene
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2023.118897

Nitrate and SMX both play a critical role in their biotransformation in biodegradable polymer-supported denitrification biofilters. However, the mutual influences of nitrate and SMX on their biotransformation for long-term operation remained obscure. Results showed SMX and nitrate had divergent effects on SMX removal. SMX removal rates was positively related with its loading rates, whereas they were negatively related to NLRs. The most abundant metabolite C10H14O3N3S (the reduced form of SMX moiety) from the N–O bond cleavage pathway by UHPLC-LTQ-Orbitrap-MS/MS and effluent TOC variations confirmed the presence of electron donor competition between nitrate and SMX. SMX less than 1000 μg/L had a negligible influence on denitrification performance. Denitrifiers such as Azospira and Denitratisoma were still enriched after chronic exposure, and nosZ/narG positively correlated with sul1/sul2 resistance genes, which were both responsible for the negligible influence of SMX. This work could guide the operational management of denitrification biofilters for simultaneous nitrate and antibiotics removal.
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•SMX removal rates was positively related to its initial loading rates.•Electron donor competition between NO3−-N and SMX occurred with increasing NLRs.•The key transformation intermediate was identified as the reduced form of SMX moiety.•Denitrifiers like Azospira were still enriched after chronic exposure to SMX.•There were positive correlations between sul1/sul2 resistance genes and nosZ/narG.