近年来，纳滤（NF）已被证明是消毒副产品（DBP）前体控制的可行选择。由于DBP前体截留是天然有机物（NOM）和膜之间物理化学相互作用的复杂函数，了解聚乙二醇（PEG）等中性化合物的行为将是阐明有机物截留的重要第一步。研究PEG截留特性也将有助于使用中性线性化合物建立基线截留，以更好地理解NOM膜相互作用。分子量截止值（MWCO）是一个常用参数，用于指定用于有机物去除的超滤膜和纳滤膜。然而，它的测定还没有标准化，导致在膜实施和各种研究结果的比较中出现粘融合。浓差极化是溶质在膜附近聚集的现象。 这会改变观察到的排斥反应的“真实”值。截留率直接取决于凝胶浓度；因此，获得凝胶层浓度的准确值对于计算真实截留率非常重要。两种通常用于计算真实排斥率的方法是凝胶层模型和渗透压模型。尽管使用这两个模型计算凝胶层浓度已经做了很多工作，但这些模型与我们的知识还没有直接的比较。本文的目的是描述各种过程变量对浓差极化的影响及其对MWCO测定的影响。为此，在恒定流量下进行了横流实验。包括13个参考文献，图。

In recent years, nanofiltration (NF) has been proven to be a viable option for disinfectionbyproduct (DBP) precursor control. Because DBP precursor rejection is a complexfunction of physicochemical interactions between natural organic matter (NOM) andmembranes, understanding the behavior of neutral compounds such as polyethyleneglycol (PEG) will be an important first step in elucidating organics rejection. StudyingPEG rejection characteristics will also help in establishing a baseline rejection usingneutral linear compounds to better understand NOM-membrane interactions. Molecular weight cut off (MWCO) is a commonparameter to specify ultrafiltration and nanofiltration membranes employed for organicsremoval. However, its determination has not yet been standardized leading to muchconfusion in membrane implementation and comparison of results from various studies.Concentration polarization is the phenomenon when solutes tend to accumulate near themembrane. This changes the observed rejection from its "true" value. The truerejection directly depends upon the gel concentration; hence obtaining an accurate valueof the gel layer concentration is important to calculate the true rejection. Twoapproaches usually employed to calculate the true rejection are the gel layer model andthe osmotic pressure model.Although, much work has been done using both models to calculate gel layerconcentration, there has been no direct comparison of these models to ourknowledge. The objective of this paper is to delineate the effect of various processvariables on concentration polarization and its implication on MWCO determination.To this end, cross flow experiments were conducted at constant flux. Includes 13 references, figure.