Key Laboratory of Membrane Separation of Shaanxi Province, School of Environmental & Municipal Engineering, Xi'an University of Architecture and Technology, Yan Ta Road. No.13, Xi'an, 710055, China.
Sci Rep. 2017 Jun 6;7(1):2895. doi: 10.1038/s41598-017-03190-1.
Extra-cellular polymeric substances (EPS) are a major cause of membrane fouling in membrane bioreactors (MBRs). In this study, an anoxic-oxic membrane bioreactor (A/O-MBR) was run continuously for 98 days. The runs were divided into three stages according to hydraulic retention time (HRT) (11.8, 12.5 and 14.3 h, respectively). EPS were extracted from the reactor under the different HRTs. A quartz crystal microbalance with dissipation monitoring (QCM-D) and Fourier transform infrared (FT-IR) were used to study the adherence layer structures and the adsorption behaviours of EPS on the membrane surface. The results indicated that the removal rate of TN was more susceptible to HRT than NH-N. The observations in the QCM-D suggested that at the lowest HRT (11.8 h), the structure of the adsorption layer is loose and soft and the fluidity was better than for HRTs of 12.5 or 14.3 h. It is likely one of the major reasons for the rapidly blocking of the membrane pores. Furthermore, the higher EPS adherence as analyzed in the QCM-D and EPS concentration could induce a higher osmotic pressure effect, leading to a rapid membrane-fouling rate.
胞外聚合物（EPS）是膜生物反应器（MBR）中膜污染的主要原因之一。本研究连续运行缺氧-好氧膜生物反应器（A/O-MBR）98 天。根据水力停留时间（HRT）将运行分为三个阶段（分别为 11.8、12.5 和 14.3 h）。在不同的 HRT 下从反应器中提取 EPS。采用石英晶体微天平（QCM-D）和傅里叶变换红外光谱（FT-IR）研究 EPS 在膜表面的附着层结构和吸附行为。结果表明，TN 的去除率比 NH-N 对 HRT 更敏感。QCM-D 的观察结果表明，在最低 HRT（11.8 h）下，吸附层的结构松散且柔软，其流动性优于 HRT 为 12.5 或 14.3 h 的情况。这可能是导致膜孔迅速堵塞的主要原因之一。此外，QCM-D 分析和 EPS 浓度表明 EPS 附着率较高会引起较高的渗透压效应，从而导致膜污染速率迅速增加。
