Maeda Yasushi
LG Chem Japan Co., Ltd., Kyobashi Trust Tower 12F, 2-1-3 Kyobashi Chuo-ku, Tokyo 104-0031, Japan.
Membranes (Basel). 2024 Oct 17;14(10):221. doi: 10.3390/membranes14100221.
Reverse osmosis (RO) and nanofiltration (NF) are ubiquitous technologies in modern water treatment, finding applications across various sectors. However, the availability of high-quality water suitable for RO/NF feed is diminishing due to droughts caused by global warming, increasing demand, and water pollution. As concerns grow over the depletion of precious freshwater resources, a global movement is gaining momentum to utilize previously overlooked or challenging water sources, collectively known as "marginal water". Fouling is a serious concern when treating marginal water. In RO/NF, biofouling, organic and colloidal fouling, and scaling are particularly problematic. Of these, organic fouling, along with biofouling, has been considered difficult to manage. The major organic foulants studied are natural organic matter (NOM) for surface water and groundwater and effluent organic matter (EfOM) for municipal wastewater reuse. Polymeric substances such as sodium alginate, humic acid, and proteins have been used as model substances of EfOM. Fouling by low molecular weight organic compounds (LMWOCs) such as surfactants, phenolics, and plasticizers is known, but there have been few comprehensive reports. This review aims to shed light on fouling behavior by LMWOCs and its mechanism. LMWOC foulants reported so far are summarized, and the role of LMWOCs is also outlined for other polymeric membranes, e.g., UF, gas separation membranes, etc. Regarding the mechanism of fouling, it is explained that the fouling is caused by the strong interaction between LMWOC and the membrane, which causes the water permeation to be hindered by LMWOCs adsorbed on the membrane surface (surface fouling) and sorbed inside the membrane pores (internal fouling). Adsorption amounts and flow loss caused by the LMWOC fouling were well correlated with the octanol-water partition coefficient (log P). In part 2, countermeasures to solve this problem and applications using the LMWOCs will be outlined.
反渗透（RO）和纳滤（NF）是现代水处理中普遍存在的技术，在各个领域都有应用。然而，由于全球变暖导致的干旱、需求增加和水污染，适合RO/NF进水的优质水供应正在减少。随着对珍贵淡水资源枯竭的担忧日益增加，一场利用以前被忽视或具有挑战性的水源（统称为“边际水”）的全球运动正在兴起。处理边际水时，污垢是一个严重问题。在RO/NF中，生物污垢、有机和胶体污垢以及结垢尤其成问题。其中，有机污垢与生物污垢一起，被认为难以管理。研究的主要有机污垢物质是地表水和地下水的天然有机物（NOM）以及城市废水回用的出水有机物（EfOM）。海藻酸钠、腐殖酸和蛋白质等聚合物物质已被用作EfOM的模型物质。已知表面活性剂、酚类和增塑剂等低分子量有机化合物（LMWOCs）会造成污垢，但综合报告很少。本综述旨在阐明LMWOCs的污垢行为及其机制。总结了迄今为止报道的LMWOC污垢物质，并概述了LMWOCs在其他聚合物膜（如超滤膜、气体分离膜等）中的作用。关于污垢机制，解释为污垢是由LMWOC与膜之间的强烈相互作用引起的，这导致吸附在膜表面的LMWOCs（表面污垢）和吸附在膜孔内部的LMWOCs（内部污垢）阻碍了水的渗透。LMWOC污垢引起的吸附量和流量损失与辛醇-水分配系数（log P）密切相关。在第二部分中，将概述解决此问题的对策以及使用LMWOCs的应用。
