Waste activated sludge serves an important reservoir for antibiotics within wastewater treatment plants, and understanding the occurrence and evolution of antibiotics during sludge treatment is crucial to mitigate the potential risks of subsequent resource utilization of sludge. This study explores the degradation and transformation mechanisms of three typical antibiotics, oxytetracycline (OTC), ofloxacin (OFL), and azithromycin (AZI) during sludge hydrothermal treatment (HT), and investigates the influence of biopolymers transformation on the fate of these antibiotics. The findings indicate that HT induces a shift of antibiotics from solid-phase adsorption to liquid-phase dissolution in the initial temperature range of 25–90 °C, underscoring this phase's critical role in preparing antibiotics for subsequent degradation phases. Proteins (PN) and humic acids emerge as crucial for antibiotic binding, facilitating their redistribution within sludge. Specifically, the binding capacity sequence of biopolymers to antibiotics is as follows: OFL>OTC>AZI, highlighting that OFL-biopolymers display stronger electrostatic attraction, more available adsorption sites, and more stable binding strength. Furthermore, antibiotic degradation mainly occurs above 90 °C, with AZI being the most temperature-sensitive, degrading 92.97% at 180 °C, followed by OTC (91.26%) and OFL (52.51%). Concurrently, the degradation products of biopolymers compete for active sites to form novel amino acid-antibiotic conjugates, which inhibits the further degradation of antibiotics. These findings illuminate the effects of biopolymers evolution on intricate dynamics of antibiotics fate in sludge HT and are helpful to optimize the sludge HT process for effective antibiotics abatement.

中文翻译：

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污水污泥水热处理过程中抗生素的固液再分布和降解：生物聚合物与抗生素之间的相互作用

废弃活性污泥是污水处理厂内抗生素的重要储存库，了解污泥处理过程中抗生素的发生和演化对于降低污泥后续资源化利用的潜在风险至关重要。本研究探讨了土霉素（OTC）、氧氟沙星（OFL）和阿奇霉素（AZI）三种典型抗生素在污泥水热处理（HT）过程中的降解和转化机制，并研究了生物聚合物转化对这些抗生素命运的影响。研究结果表明，HT 在 25-90 °C 的初始温度范围内诱导抗生素从固相吸附转变为液相溶解，强调了该阶段在为后续降解阶段准备抗生素中的关键作用。蛋白质 (PN) 和腐殖酸对于抗生素结合至关重要，有助于它们在污泥中的重新分配。具体而言，生物聚合物与抗生素的结合能力顺序如下：OFL>OTC>AZI，这表明OFL-生物聚合物表现出更强的静电吸引力、更多的可用吸附位点和更稳定的结合强度。此外，抗生素降解主要发生在90℃以上，其中AZI对温度最敏感，在180℃时降解92.97%，其次是OTC（91.26%）和OFL（52.51%）。同时，生物聚合物的降解产物竞争活性位点，形成新型氨基酸-抗生素缀合物，从而抑制抗生素的进一步降解。这些发现阐明了生物聚合物进化对污泥高温处理中抗生素归宿的复杂动态的影响，并有助于优化污泥高温处理工艺以有效地减少抗生素。