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 μg/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.

回收水中普遍存在痕量磺胺类抗生素，但当这些水用于恢复干涸河流的水流时，完全去除这些化学物质的环境途径尚不清楚。本研究调查了来自再生水主导河流的七种沉积物的磺胺吸附-解吸、生物降解和矿化过程。在有氧和缺氧（硝酸盐还原）条件下进行批量实验，并在环境相关浓度（≤ 10 μg/L）下分别评估磺胺二甲嘧啶、磺胺嘧啶和磺胺甲恶唑 (SMX) 的每个去除过程。在 28 天内，44 ± 32% 的磺胺被生物降解，而完全矿化成二氧化碳的比例 < 1%。通过沉积物吸附去除了大约 5% 的磺胺类药物，与底泥有机质含量呈正相关。SMX 生物降解的详细研究表明，虽然它在第 2 天在缺氧试验中的转化似乎比在好氧试验中更快，但它在 28 天内逆转，在缺氧试验中（69±25 天）比在好氧试验中的表观半衰期更长（ 12 ± 11 天）。这归因于在反硝化条件下形成可逆代谢物，例如 DesAmino-SMX，其生产受亚硝酸盐浓度的影响。尽管测量了三种经常报告的代谢物，但在本研究中，> 70% 的生物转化产物仍然未知。研究结果强调了磺胺类药物及其衍生物的持久性，需要进行研究以进一步阐明降解机制并进行再生水再利用的风险评估。SMX 生物降解的详细研究表明，虽然它在第 2 天在缺氧试验中的转化似乎比在好氧试验中更快，但它在 28 天内逆转，在缺氧试验中（69±25 天）比在好氧试验中的表观半衰期更长（ 12 ± 11 天）。这归因于在反硝化条件下形成可逆代谢物，例如 DesAmino-SMX，其生产受亚硝酸盐浓度的影响。尽管测量了三种经常报告的代谢物，但在本研究中，> 70% 的生物转化产物仍然未知。研究结果强调了磺胺类药物及其衍生物的持久性，需要进行研究以进一步阐明降解机制并进行再生水再利用的风险评估。SMX 生物降解的详细研究表明，虽然它在第 2 天在缺氧试验中的转化似乎比在好氧试验中更快，但它在 28 天内逆转，在缺氧试验中（69±25 天）比在好氧试验中的表观半衰期更长（ 12 ± 11 天）。这归因于在反硝化条件下形成可逆代谢物，例如 DesAmino-SMX，其生产受亚硝酸盐浓度的影响。尽管测量了三种经常报告的代谢物，但在本研究中，> 70% 的生物转化产物仍然未知。研究结果强调了磺胺类药物及其衍生物的持久性，需要进行研究以进一步阐明降解机制并进行再生水再利用的风险评估。