正渗透（Forward osmosis, FO）是国际上广泛关注的新型膜分离技术，能耗低、水回收率高，其分离的驱动力来源于原料液和驱动液之间自然存在的渗透压差。浓差极化与膜污染是导致水通量下降的两个主要因素。增加错流流速可显著减少外部浓差极化对FO性能的负面影响，内部浓差极化只能通过改善膜结构和膜性能来减缓。膜污染是FO的技术障碍之一。产生膜污染的机理有膜表面吸附与滤饼层（凝胶层）形成。膜污染物质可分为溶解性无机物、胶体和悬浮物、有机物及微生物。FO膜的性质、原料液性质、膜的置向、操作条件均是膜污染的影响因素。控制膜污染的方法主要有预处理、流体力学方法、清洗、改变膜的结构等。研究膜污染机理及控制方法可促进FO技术的开发与应用。
 

 Forward osmosis (FO), a novel membrane separation technology with low energy consumption and high water recovery, has been drawn attention around the world. Its driving force for separation is natural pressure difference existing between the feed solution and draw solution. Concentration polarization and membrane fouling are two main factors resulting in decrease in water flux. Increase in cross-flow velocity would significantly reduce negative influence of external concentration polarization on FO performance. Internal concentration polarization could only be reduced through improvement on membrane structure and membrane performance. Membrane fouling is one of the technical barriers of FO. Mechanism of membrane fouling includes adsorption on membrane surface and cake layer (gel layer) formation. Membrane foulants include dissolved inorganic matter, colloid and suspended matter, organic matter, and microorganisms. Properties of FO membrane and feed solution, membrane orientation, and operating conditions are the affecting factors of membrane fouling. The methods for fouling control include pretreatment, hydraulic methods, cleaning, and modification of membrane structure, etc. Research on mechanisms of membrane fouling and its control methods can promote the development and application of FO technology.
 

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