摘要

       抗生素抗性基因 (ARG) 是污水处理厂 (WWTP) 中一个新出现的问题，因为 ARG 的传播会对人类健康构成严重威胁。然而，很少有研究对膜生物反应器 (MBR) 中的 ARG 进行量化，尽管 MBR 已广泛用于市政和工业废水处理。为了揭示 MBR 去除 ARG 的能力和抗生素暴露后膜污染的反应，通过实验室规模的系统膜污染分析对五种典型的 ARG 亚型（sulI、sulII、tetC、tetX 和 ereA）和 int1 进行量化缺氧/好氧膜生物反应器 (A/O-MBR)。添加磺胺甲恶唑和盐酸四环素使活性污泥中的 ARG 丰度增加了 0.5-1.4 个数量级，而膜组件的 ARG 去除性能保持稳定（在某些情况下甚至随着 ARG 的绝对丰度而增加），去除的 ARG 丰度范围从 0.6 到 5.6 个数量级。具体而言，膜污染物中 ARG 的分布占所有测试 MBR 样品总绝对丰度的 13%–25%。事实上，在添加抗生素后发生了大量污染，在膜污染循环中，可溶性微生物产物 (SMP) 和细胞外聚合物 (EPS) 的平均浓度分别增加了 340% 和 220%；此外，膜污染物中EPS和SMP的含量与膜污染物的ARG绝对丰度显着相关（p < 0.05），其中蛋白质和多糖之间的相关性比腐植酸的相关性更显着。致密的膜污染层和膜本身构成了双重屏障，有效避免了 ARGs 从膜组件中泄漏。我们的研究结果为 MBR 系统中 ARG 的增殖和去除提供了基本见解，并强调了膜污染对 ARG 去除的贡献，因为 MBR 作为降低 WWTP 流出物中 ARG 水平的有效策略的潜力。

Antibiotic resistance genes (ARGs) are an emerging concern in wastewater treatment plants (WWTPs), as dissemination of ARGs can pose a serious risk to human health. Few studies, however, have quantified ARGs in membrane bioreactors (MBRs), although MBRs have been widely used for both municipal and industrial wastewater treatment. To reveal the capacity of MBRs for removal of ARGs and the response of membrane fouling after antibiotic exposure, five typical ARG subtypes (sulI, sulII, tetC, tetX and ereA) and int1 were quantified affiliated by systematic membrane foulants analysis in a laboratory-scale anoxic/aerobic membrane bioreactor (A/O-MBR). Sulfamethoxazole and tetracycline hydrochloride additions increased ARG abundances by 0.5–1.4 orders of magnitude in the activated sludge, while the ARG removal performance of the membrane module remained stable (or even increased with ARG absolute abundance in several cases), with the abundance of removed ARGs ranging from 0.6 to 5.6 orders of magnitude. Specifically, the distribution of ARGs in membrane foulants accounted for 13%–25% of the total absolute abundance of all tested MBR samples. Indeed, substantial fouling occurred after the antibiotic additions, with the mean concentrations of soluble microbial product (SMP) and extracellular polymeric substance (EPS) increasing by 340% and 220%, respectively, in a membrane fouling cycle; moreover, the contents of EPS and SMP in the membrane foulants were significantly correlated with the ARG absolute abundance of membrane foulants (p < 0.05), among which more significant correlations occurred between both the protein and polysaccharide of foulants than that with humic acid. The dense membrane fouling layer and the membrane itself constituted dual barriers that effectively avoided the leakage of ARGs from the membrane module. Our findings provide fundamental insights into the proliferation and removal of ARGs in MBR systems, and highlight the contribution of membrane fouling to ARG removals in terms of the potential of MBR as an effective strategy to reduce ARG levels in WWTP effluent.

https://www.sciencedirect.com/science/article/abs/pii/S0043135417309582