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    污水处理系统中抗生素耐药性污染的环境散逸风险评估

    Environmental Dissipation Risk Assessment of Antibiotic Resistance Pollution in Wastewater Treatment Systems

    • 摘要: 抗生素耐药性污染已成为全球公共卫生与生态安全的重要挑战,污水处理厂(Wastewater Treatment Plants, WWTPs)被认为是抗生素耐药基因(Antibiotic Resistance Genes, ARGs)的重要储库与污染源。为评估ARGs污染散逸风险,本研究整合并分析了全球公开的污水及其受纳河道的宏基因组数据集。经筛选,共获取涵盖11个国家的29座WWTPs宏基因组数据集。结果表明,共检出隶属于27种大类的1 794种ARGs亚型,其中进水样本的ARGs丰度(平均2.16 copies/cell)与多样性(平均556种亚型)显著高于其出水与受纳河道;经全流程污水处理工艺后,出水仍保持平均丰度0.65 copies/cell、295种亚型。受纳水体下游较上游平均丰度和多样性分别增加了39.5%和11.3%;基于考量ARGs赋存特征、可移动性与宿主致病性的样品耐药性综合风险评估模型,揭示下游河道的风险量值平均升高35%。进一步基于增殖特征,识别出23种具有环境散逸风险的污水源ARGs亚型,其总丰度占受纳水体下游22.6%。研究发现,不同处理工艺对ARGs的去除效果存在显著差异:厌氧−缺氧−好氧工艺(AAO)、氧化沟(OD)和序批式活性污泥法(SBR)对具有散逸风险的污水源ARGs总去除率均超过80%,而周期循环活性污泥法(CASS)和膜生物反应器(MBR)对其具有选择性富集效应。本研究构建的环境散逸风险分析框架、识别的典型污水源ARGs类别及关键工艺去除效能谱系,可为后续耐药性污染物传播机制研究提供可参照的科学范式,研究成果亦为污染优先管控策略的制定提供了精准靶标。

       

      Abstract: Antibiotic resistance pollution has become a major threat to public health and ecological security, and wastewater treatment plants (WWTPs) are widely recognized as important reservoirs and emission sources of antibiotic resistance genes (ARGs). To quantify the environmental dissemination risk of wastewater-borne resistomes, we integrated and reanalyzed 81 metagenomic samples from 29 WWTPs in 11 countries, encompassing influent, effluent, and paired upstream and downstream receiving river samples. These publicly available datasets span approximately the last decade and cover eight representative biological treatment configurations. In total, 1,794 ARG subtypes affiliated with 27 ARG types were detected. Influent samples exhibited significantly higher ARG abundance (mean: 2.16 copies/cell) and diversity (mean: 556 subtypes) than effluent and river samples. Even after full-scale wastewater treatment, effluents retained a mean abundance of 0.65 copies/cell and a mean of 295 ARG subtypes, indicating incomplete elimination of wastewater-derived resistomes. Compared with upstream river water, downstream sites showed mean increases of 39.5% in ARG abundance and 11.3% in ARG diversity. To move beyond descriptive resistome profiling, we applied a structured, comprehensive risk assessment framework based on MetaCompare (v2.0). This framework integrates three dimensions of ARG-related risk: occurrence features, mobility potential, and host pathogenicity. The results showed that the overall resistome risk score of downstream receiving waters increased by an average of 35%, indicating that wastewater discharge elevates ARG loads and amplifies their potential ecological and health relevance. Building on this risk-oriented analysis, we identified 23 wastewater-derived ARGs posing dissemination risks according to their occurrence, persistence, and downstream proliferation characteristics. Collectively, these high-risk subtypes accounted for 22.6% of the total ARG abundance in downstream waters. Among them, qacH, mexW, and oqxB displayed particularly strong environmental proliferation potential, whereas APH(6)-Id, aadA, sul1, and sul2 warrant special concern as they are also classified as clinically important high-risk ARGs. Marked differences were observed among treatment processes. The anaerobic-anoxic-oxic (AAO), oxidation ditch (OD), and sequencing batch reactor (SBR) processes removed more than 80% of the wastewater-derived ARGs with dissemination risk, whereas the cyclic activated sludge system (CASS) and membrane bioreactor (MBR) processes showed selective enrichment effects for several subtypes. A plausible explanation is that the fluctuating redox and substrate conditions in the CASS, coupled with the high biomass density, prolonged sludge retention time, biofilm- or membrane-associated microbial aggregation, and residual extracellular DNA in the MBR, create favorable niches for the persistence, horizontal transfer, or selective enrichment of certain ARGs. Overall, the environmental dissemination risk framework established here, the identification of representative wastewater-derived high-risk ARGs, and the evaluation of process-specific removal spectra provide a solid scientific foundation for mechanistic studies and the development of targeted mitigation strategies against antibiotic resistance pollution.

       

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