The establishment of a multi-stage membrane system that integrates different membrane technologies has been regarded as an essential process in industry brine recycling. Although membrane fouling has been intensively studied, in particular, on single membrane unit at the lab-scale, the actual fouling behavior in multi-stage integrated pilot systems has not yet been fully understood. In this study, membrane fouling was systematically investigated in a pilot-scale RO-NF process by monitoring the surface properties of fouling layer and the deposition behavior of foulants. Distinct spatial fouling variation along the flow direction of the multi-stage integrated system was observed. At the first stage of the RO process, severe fouling occurred on the membrane surface under the synergistic interaction of several organic and inorganic foulants, resulting in a rough and thick cake layer. The membrane fouling at the second RO stage became less severe. During the following NF process, the amounts of metal oxides/hydroxides and organic foulants depositing on the membrane surface decreased. The results indicated that the foulants firstly deposited on the front stage of the integrated RO-NF process. Overall, the observations for spatially varied membrane fouling help to advance understanding of membrane technologies to achieve zero liquid discharge in the steel industry.

建立集成不同膜技术的多级膜系统已被视为工业卤水回收的重要工艺。尽管已经对膜污染进行了深入研究，特别是在实验室规模的单个膜单元上，但尚未完全了解多级集成中试系统中的实际污染行为。在这项研究中，通过监测污垢层的表面性质和污垢的沉积行为，在中试规模的 RO-NF 工艺中系统地研究了膜污垢。观察到沿多级集成系统流动方向的明显空间结垢变化。在 RO 工艺的第一阶段，在几种有机和无机污染物的协同作用下，膜表面发生了严重的污染，导致蛋糕层粗糙而厚实。第二反渗透阶段的膜污染变得不那么严重了。在接下来的 NF 过程中，沉积在膜表面的金属氧化物/氢氧化物和有机污染物的数量减少了。结果表明，污垢首先沉积在集成RO-NF工艺的前级。总体而言，对空间变化的膜污染的观察有助于加深对膜技术的理解，以实现钢铁行业的零液体排放。结果表明，污垢首先沉积在集成RO-NF工艺的前级。总体而言，对空间变化的膜污染的观察有助于加深对膜技术的理解，以实现钢铁行业的零液体排放。结果表明，污垢首先沉积在集成RO-NF工艺的前级。总体而言，对空间变化的膜污染的观察有助于加深对膜技术的理解，以实现钢铁行业的零液体排放。