Loose nanofiltration (NF) membranes are an attractive avenue in effective separation of organic matters and salts for resource recovery from highly-loaded wastewater. However, membrane fouling remains an unclear and complex factor in practical applications. In this work, the flux of a loose NF membrane fouled by humic acid at various solution compositions was systematically investigated. The strong hydrophilicity of the loose NF membrane allows for slight deposition of humic acid on the membrane surface, yielding an outstanding antifouling performance. However, a moderate flux decline was observed at low pH and high ionic strength, due to reduction in charge density of membrane surface for formation of a porous foulant layer. At higher ionic strength, cake-enhanced concentration polarization was the fouling mechanism that dominates the membrane flux. The presence of calcium ions induced bridging between humic acid molecules to generate a compact foulant layer, tremendously deteriorating the membrane flux. Based on COMSOL simulation for the membrane module, the hydrodynamics near the membrane surface had a more significant effect on membrane fouling than the solution chemistry, which is consistent with scanning electronic microscopy observation. This indicates benign hydrodynamic condition can be an effective strategy to fouling control for loose NF membranes.

松散的纳滤（NF）膜是有效分离有机物和盐以从高负荷废水中进行资源回收的一种有吸引力的途径。然而，在实际应用中，膜结垢仍是不清楚和复杂的因素。在这项工作中，系统地研究了腐殖酸在各种溶液成分下污染的疏松NF膜通量。松散的NF膜具有很强的亲水性，允许腐殖酸在膜表面上轻微沉积，从而产生出色的防污性能。然而，由于降低了用于形成多孔污垢层的膜表面的电荷密度，因此在低pH和高离子强度下观察到适度的通量下降。在较高的离子强度下 滤饼增强的浓度极化是控制膜通量的结垢机理。钙离子的存在引起腐殖酸分子之间的桥接，从而产生致密的污垢层，从而大大降低了膜通量。基于COMSOL对膜组件的仿真，膜表面附近的流体动力学对膜结垢的影响比溶液化学影响更大，这与扫描电子显微镜观察相符。这表明良性的流体动力学条件可以是控制松散的NF膜结垢的有效策略。膜表面附近的流体动力学比溶液化学对膜结垢的影响更大，这与扫描电子显微镜观察一致。这表明良性的流体动力学条件可以是控制松散的NF膜结垢的有效策略。膜表面附近的流体动力学比溶液化学对膜结垢的影响更大，这与扫描电子显微镜观察一致。这表明良性的流体动力学条件可以是控制松散的NF膜结垢的有效策略。