Abstract In this work, the dynamic changes in the composition of fouling layer as a function of operating time were systematically investigated and compared in forward osmosis (FO) based membrane processes for municipal wastewater treatment. Fouled membranes were collected from four different operational cycles (3, 8, 16 and 30 days) and prepared for quantitative analyses of organic and inorganic foulants and microscopic observation by confocal laser scanning microscopy (CLSM). Moreover, the dynamic changes of bacterial concentration and community structure were characterized by the plate count method and Illumina MiSeq sequencing, respectively. The results showed that with the extension of operation time, the amount of organic foulants, inorganic species and bacteria deposited on the membrane surface exhibited a gradual increase trend in direct FO, resulting in a corresponding increase of fouling resistance and decline of water flux. As for OMBR, apart from the organic foulants such as polysaccharides and proteins, both the inorganic species and membrane surface bacterial concentration reached to a plateau phase after 8 days of operation, leading to a much lower fouling resistance and flux reduction. The bacterial community analysis indicated that two dominant genus were detected in the biofilm of OMBR; however, the bacterial community on the membrane surface of direct FO exhibited a significantly higher diversity but with a lower abundance.

中文翻译：

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基于正渗透膜法的市政污水处理中污垢层的动态变化

摘要 在这项工作中，系统地研究和比较了基于正向渗透 (FO) 的城市污水处理膜工艺中污垢层组成随运行时间的动态变化。从四个不同的操作周期（3、8、16 和 30 天）收集污染膜，并准备用于有机和无机污染物的定量分析和共聚焦激光扫描显微镜 (CLSM) 的显微观察。此外，细菌浓度和群落结构的动态变化分别通过平板计数法和Illumina MiSeq测序来表征。结果表明，随着操作时间的延长，有机污染物的产生量、沉积在膜表面的无机物种和细菌在直接 FO 中表现出逐渐增加的趋势，导致污垢阻力相应增加和水通量下降。对于OMBR，除了多糖和蛋白质等有机污染物外，无机物种和膜表面细菌浓度在运行8天后均达到平台期，导致抗污染性和通量降低很多。细菌群落分析表明在OMBR生物膜中检测到两个优势属；然而，直接 FO 膜表面的细菌群落表现出显着更高的多样性，但丰度较低。除多糖和蛋白质等有机污染物外，运行8天后无机物种和膜表面细菌浓度均达到平台期，导致耐污染性和通量降低。细菌群落分析表明在OMBR生物膜中检测到两个优势属；然而，直接 FO 膜表面的细菌群落表现出显着更高的多样性，但丰度较低。除多糖和蛋白质等有机污染物外，运行8天后无机物种和膜表面细菌浓度均达到平台期，导致耐污染性和通量降低。细菌群落分析表明在OMBR生物膜中检测到两个优势属；然而，直接 FO 膜表面的细菌群落表现出显着更高的多样性，但丰度较低。