The fate of antibiotics in activated sludge has attracted increasing interests. However, the focus needs to shift from concerning removal efficiencies to understanding mechanisms and sludge responding to antibiotic toxicity. Herein, we operated two anaerobic sequencing batch reactors (ASBRs) for 200 days with sulfadiazine (SDZ) and sulfamethoxazole (SMX) added. The removal efficiency of SMX was higher than that of SDZ. SDZ was removed via adsorption (9.91–21.18%) and biodegradation (10.20–16.00%), while biodegradation (65.44–86.26%) was dominant for SMX removal. The mechanisms involved in adsorption and biodegradation were investigated, including adsorption strength, adsorption sites and the roles of enzymes. Protein-like substance (tryptophan) functioned vitally in adsorption by forming complexes with sulfonamides. P450 enzymes may catalyze sulfonamides degradation via hydroxylation and desulfurization. Activated sludge showed distinct responses to different sulfonamides, reflected in the changes of microbial communities and functions. These responses were related to sulfonamides removal, corresponding to the stronger adsorption capacity of activated sludge in ASBR-SDZ and degradation capacity in ASBR-SMX. Furthermore, the reasons for different removal efficiencies of sulfonamides were analyzed according to steric and electronic effects. These findings propose insights into antibiotic removal and broaden the knowledge for self-protection mechanisms of activated sludge under chronic toxicities of antibiotics.

活性污泥中抗生素的命运引起了越来越多的关注。然而，重点需要从关注去除效率转移到了解机制和污泥对抗生素毒性的反应。在这里，我们在添加了磺胺嘧啶 (SDZ) 和磺胺甲恶唑 (SMX) 的情况下运行了两个厌氧序批式反应器 (ASBR) 200 天。SMX的去除效率高于SDZ。SDZ 通过吸附 (9.91–21.18%) 和生物降解 (10.20–16.00%) 去除，而生物降解 (65.44–86.26%) 主要用于 SMX 去除。研究了吸附和生物降解所涉及的机制，包括吸附强度、吸附位点和酶的作用。蛋白质样物质（色氨酸）通过与磺胺类形成复合物在吸附中发挥重要作用。P450 酶可通过羟基化和脱硫催化磺胺类药物降解。活性污泥对不同磺胺类药物表现出明显的反应，反映在微生物群落和功能的变化上。这些反应与磺胺类药物的去除有关，对应于 ASBR-SDZ 中活性污泥的更强吸附能力和 ASBR-SMX 中的降解能力。此外，还根据空间和电子效应分析了磺胺类药物去除效率不同的原因。这些发现提出了对抗生素去除的见解，并拓宽了活性污泥在抗生素慢性毒性下的自我保护机制的知识。反映在微生物群落和功能的变化上。这些反应与磺胺类药物的去除有关，对应于 ASBR-SDZ 中活性污泥的更强吸附能力和 ASBR-SMX 中的降解能力。此外，还根据空间和电子效应分析了磺胺类药物去除效率不同的原因。这些发现提出了对抗生素去除的见解，并拓宽了活性污泥在抗生素慢性毒性下的自我保护机制的知识。反映在微生物群落和功能的变化上。这些反应与磺胺类药物的去除有关，对应于 ASBR-SDZ 中活性污泥的更强吸附能力和 ASBR-SMX 中的降解能力。此外，还根据空间和电子效应分析了磺胺类药物去除效率不同的原因。这些发现提出了对抗生素去除的见解，并拓宽了活性污泥在抗生素慢性毒性下的自我保护机制的知识。根据空间和电子效应分析了磺胺类药物去除率不同的原因。这些发现提出了对抗生素去除的见解，并拓宽了活性污泥在抗生素慢性毒性下的自我保护机制的知识。根据空间和电子效应分析了磺胺类药物去除率不同的原因。这些发现提出了对抗生素去除的见解，并拓宽了活性污泥在抗生素慢性毒性下的自我保护机制的知识。