摘要

      未经处理的废水可能含有高水平的抗生素抗性基因（ARGs），这使得城市污水处理厂（WWTPs）对于控制ARGs向环境中的释放至关重要。本研究的目的是探讨两个三级污水处理厂的个别处理步骤如何影响ARGs的去除（copies/mL）和相对丰度（copies/copies 16srRNA基因）。利用定量实时PCR（qPCR）技术，对9个代表对常用抗生素耐药的ARG标志物和1个评价ARG迁移潜能的整合子基因（intl1）进行了定量分析。这两个污水处理厂均符合省污水处理条例，以去除含碳耗氧量（CBOD5）和总悬浮固体。10个ARG标记（intl1、sul1、sul2、tet（O）、ermB、blaCTX-M、blaTEM、qnrS）中有8个在所有样本中检测到。相比之下，mecA是间歇性检测，而vanA在所有样本中都低于检测限。采用曝气泻湖（AL）处理的植物中，总ARG标记丰度降低了1.77对数（p<0.05），采用生物脱氮（BNR）系统处理的植物中，总ARG标记丰度降低了2.69对数（p<0.05）。两个工厂的BNR和二沉池步骤提供了最多的ARGs去除率。ARGs的相对丰度在铝厂保持不变，在BNR厂呈下降趋势。CBOD5、硝酸盐和类杆菌粪便标志物水平与ARG浓度相关，提示这些变量可能有助于预测ARG的去除。综上所述，来自污水处理厂的废水中含有8种研究的ARG标记物，其浓度范围为0.01~3.6 log copies/mL，表明它们释放到环境中，然而，在两个污水处理厂的处理过程中，ARGs的相对丰度并未富集。

       Raw wastewater can contain high levels of antibiotic resistance genes (ARGs), making municipal wastewater treatment plants (WWTPs) critical for the control of the release of ARGs into the environment. The objective of this study was to investigate how individual treatment steps in two tertiary WWTPs affected the removal (copies/mL) and relative abundance of ARGs (copies/copies 16S rRNA genes). Nine ARG markers, representing resistance to commonly used antibiotics, as well as one integron gene (intl1) to assess ARG mobility potential, were quantified using quantitative real-time PCR (qPCR). Both WWTPs met provincial effluent regulations for removal of carbonaceous oxygen demand (CBOD₅) and total suspended solids. Eight of the ten ARG markers (intl1, sul1, sul2, tet(O), ermB, bla_CTX-M, bla_TEM, qnrS) were detected in all samples. In contrast, mecA was detected intermittently and vanA remained below the detection limit in all samples. The total ARG marker abundances decreased by log 1.77 (p < 0.05) in the plant using an aerated lagoon (AL), and by 2.69 logs (p < 0.05) through treatment in the plant employing a biological nutrient removal (BNR) system. The BNR and secondary clarifier steps in both plants afforded the most removal of ARGs. The relative abundance of ARGs remained unchanged at the AL plant and showed a decreasing trend at the BNR plant. Levels of CBOD_5, nitrate and the human Bacteroides fecal marker correlated with ARG concentrations, suggesting these variables may be useful in predicting ARG removal. In conclusion, the effluent coming from the WWTPs contained eight of the studied ARG markers in concentrations ranging from 0.01 to 3.6 log copies/mL, indicating their release into the environment, however, the relative abundance of ARGs was not enriched during treatment in the two WWTPs.

       https://www.sciencedirect.com/science/article/pii/S0048969718322885?via%3Dihub