Wang Zhiwei, Wu Zhichao, Tang Shujuan
State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, PR China.
Water Res. 2009 May;43(9):2504-12. doi: 10.1016/j.watres.2009.02.026. Epub 2009 Feb 27.
A pilot-scale submerged membrane bioreactor (MBR) for real municipal wastewater treatment was operated for over one year in order to investigate extracellular polymeric substances (EPS) properties and their role in membrane fouling. The components and properties of bound EPS were examined by the evaluation of mean oxidation state (MOS) of organic carbons, Fourier transform infrared (FT-IR) spectroscopy, three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy, and gel filtration chromatography (GFC), etc. Test results showed that MOS of organic carbons in the bound EPS was ranging from -0.14 to -0.51, and major components could be assessed as proteins and carbohydrates. FT-IR analysis confirmed the presence of proteins and carbohydrates in the bound EPS. The organic substances with fluorescence characteristics in the bound EPS were identified as proteins, visible humic acid-like substances and fulvic acid-like substances by EEM technology. GFC analysis demonstrated that EPS had part of higher MW molecules and a broader MW distribution than the influent wastewater. It was also found that a high shear stress imposed on mixed liquor could result in the release of EPS, which would in turn influence membrane fouling in MBRs. Bound EPS solution was observed to have a stronger potential of fouling than mixed liquor. During long-term operation of the MBR, bound EPS demonstrated positive correlations with membrane fouling while temperature was verified as a negative factor affecting EPS concentration. Compared to tightly bound EPS (TB-EPS), loosely bound EPS (LB-EPS) showed more significant correlations with membrane fouling. This critical investigation would contribute towards a better understanding of the behavior, composition and fouling potential of EPS in MBR operation.
为了研究胞外聚合物（EPS）的特性及其在膜污染中的作用，一个用于实际城市污水处理的中试规模的浸没式膜生物反应器（MBR）运行了一年多。通过评估有机碳的平均氧化态（MOS）、傅里叶变换红外（FT-IR）光谱、三维激发-发射矩阵（EEM）荧光光谱和凝胶过滤色谱（GFC）等方法，对结合态EPS的成分和特性进行了研究。测试结果表明，结合态EPS中有机碳的MOS在-0.14至-0.51之间，主要成分可评估为蛋白质和碳水化合物。FT-IR分析证实了结合态EPS中存在蛋白质和碳水化合物。通过EEM技术，结合态EPS中具有荧光特性的有机物质被鉴定为蛋白质、可见的类腐殖酸物质和类富里酸物质。GFC分析表明，EPS具有部分分子量较高的分子，且分子量分布比进水废水更宽。还发现，对混合液施加高剪切应力会导致EPS的释放，进而影响MBR中的膜污染。观察到结合态EPS溶液比混合液具有更强的污染潜力。在MBR的长期运行过程中，结合态EPS与膜污染呈正相关，而温度被证实是影响EPS浓度的负面因素。与紧密结合态EPS（TB-EPS）相比，松散结合态EPS（LB-EPS）与膜污染的相关性更为显著。这项关键研究将有助于更好地理解MBR运行中EPS的行为、组成和污染潜力。
