Meng Fangang, Zhang Hanmin, Yang Fenglin, Liu Lifen
School of Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024, People's Republic of China.
Environ Sci Technol. 2007 Jun 1;41(11):4065-70. doi: 10.1021/es062208b.
Cake layer formation on the membrane surface has been a major challenge in the operation of membrane bioreactors (MBRs). In this study, the cake layer formation mechanism in an MBR used for synthetic wastewater treatment was investigated. The major components of cake layer were systematically examined by particle size analyzer (PSA), scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), X-ray fluorescence (XRF), energy-diffusive X-ray analyzer (EDX), and Fourier transform infrared (FTIR) spectroscopy. The results indicate that the small particles in sludge suspension had a strong deposit tendency on the membrane surface. The SEM and CLSM analysis exhibited that bacterial clusters and polysaccharides were significant contributors to membrane fouling. The main components of biopolymers were identified as proteins and polysaccharide materials by the FTIR. The examination by EDX and XRF demonstrated that Mg, Al, Ca, Si, and Fe were the major inorganic elements in fouling cake. Furthermore, the results suggest that bridging between deposited biopolymers and inorganic compounds could enhance the compactness of fouling layer. During the operation of MBRs, the biopolymers and inorganic elements in the bioreactor should be controlled to minimize membrane fouling.
膜表面形成滤饼层一直是膜生物反应器（MBR）运行中的一项重大挑战。在本研究中，对用于合成废水处理的MBR中滤饼层的形成机制进行了研究。通过粒度分析仪（PSA）、扫描电子显微镜（SEM）、共聚焦激光扫描显微镜（CLSM）、X射线荧光光谱仪（XRF）、能量散射X射线分析仪（EDX）和傅里叶变换红外光谱仪（FTIR）对滤饼层的主要成分进行了系统检测。结果表明，污泥悬浮液中的小颗粒在膜表面具有很强的沉积倾向。SEM和CLSM分析表明，细菌聚集体和多糖是膜污染的重要成因。通过FTIR确定生物聚合物的主要成分是蛋白质和多糖物质。EDX和XRF检测表明，Mg、Al、Ca、Si和Fe是污染滤饼中的主要无机元素。此外，结果表明，沉积的生物聚合物与无机化合物之间的桥连作用可增强污染层的致密性。在MBR运行过程中，应控制生物反应器中的生物聚合物和无机元素，以尽量减少膜污染。
