期刊
WATER RESEARCH
卷 205, 期 -, 页码 -出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.watres.2021.117616
关键词
Antibiotics; Biodegradation; Denitrification; Reversible metabolites; Managed aquifer recharge
资金
- National Natural Science Foundation of China [41907316, 41831279]
- National Key Research and Development Program of China [2016YFC0401404]
- DANIDA Fellowship center [17-M08-GEU]
Trace levels of sulfonamide antibiotics in reclaimed water pose challenges for completely removing them when restoring flows in dried rivers. This study found that biodegradation was the main removal process for sulfonamides, with some removal also occurring through sediment sorption. Additionally, the biodegradation of SMX was faster in anoxic conditions initially, but reversed over time with a longer apparent half-life, indicating the importance of understanding degradation mechanisms in different environments.
Trace levels of sulfonamide antibiotics are ubiquitous in reclaimed water, yet environmental pathways to completely remove those chemicals are not well understood when such water is used to restore flows in dried rivers. This study investigated sulfonamide sorption-desorption, biodegradation, and mineralization processes with seven sediments from a reclaimed water-dominant river. Batch experiments were conducted under oxic and anoxic (nitrate-reducing) conditions, and each removal process of sulfamethazine, sulfadiazine, and sulfamethoxazole (SMX) was evaluated individually at environmentally relevant concentrations (<= 10 mu g/L). Over 28 days, 44 +/- 32% of sulfonamides were biodegraded, while the full mineralization to carbon dioxide was 1%. Around 5% of sulfonamides were removed via sediment sorption, with a positive correlation with sediment organic contents. Detailed investigation of SMX biodegradation revealed that although its transformation appeared to be faster in anoxic than oxic tests by day 2, it reversed over 28 days with a longer apparent half-life in anoxic tests (69 +/- 25 days) than that in oxic tests (12 +/- 11 days). This is attributed to the formation of reversible metabolites at denitrifying conditions, such as DesAmino-SMX of which the production was affected by nitrite concentrations. Despite measurements of three frequently reported metabolites, 70% biotransformation products remained unknown in this study. The findings highlight the persistency of sulfonamides and their derivatives, with research needed to further elucidate degradation mechanisms and to perform risk assessment of reclaimed water reuse.
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