摘要

       抗生素抗性基因（ARGs）是废水处理厂（WWTPs）的一个新问题，因为ARGs的传播可能对人类健康构成严重威胁。尽管膜生物反应器（mbr）已广泛应用于城市和工业废水的处理，但很少有研究对mbr中的ARGs进行定量。在实验室规模的缺氧/好氧膜生物反应器（a/O-MBR）中，通过系统的膜污染分析，对5种典型的ARG亚型（sulI、sulII、tetC、tetX和ereA）和int1进行了定量研究，以揭示膜生物反应器去除ARGs的能力和抗生素暴露后膜污染的反应。磺胺甲恶唑和盐酸四环素的加入使活性污泥中ARG的丰度增加了0.5-1.4个数量级，而膜组件的ARG去除性能保持稳定（甚至在某些情况下随着ARG绝对丰度的增加而增加），去除的arg的丰度在0.6到5.6个数量级之间。其中，ARGs在膜污染源中的分布占MBR样品绝对丰度的13%-25%。事实上，添加抗生素后，膜污染循环中可溶性微生物产物（SMP）和胞外聚合物（EPS）的平均浓度分别增加了340%和220%；此外，膜污染区EPS和SMP含量与膜污染区ARG绝对丰度显著相关（p<0.05），其中蛋白和多糖含量与腐殖酸含量的相关性更显著。致密的膜污染层和膜本身构成了双重屏障，有效地避免了ARGs从膜组件中的泄漏。我们的研究结果为膜生物反应器系统中ARGs的增殖和去除提供了基本的见解，并强调了膜污染对ARG去除的贡献，因为膜生物反应器作为降低污水处理厂废水中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?via%3Dihub