Maeda Yasushi
LG Chem Japan Co., Ltd., Kyobashi Trust Tower 12F, 2-1-3 Kyobashi Chuo-ku, Tokyo 104-0031, Japan.
Membranes (Basel). 2025 Mar 17;15(3):94. doi: 10.3390/membranes15030094.
Fouling, particularly from organic fouling and biofouling, poses a significant challenge in the RO/NF treatment of marginal waters, especially wastewater. Part 1 of this review detailed LMWOC fouling mechanisms. Part 2 focuses on countermeasures and applications. Effective fouling prevention relies on pretreatment, early detection, cleaning, optimized operation, and in situ membrane modification. Accurate fouling prediction is crucial. Preliminary tests using flat-sheet membranes or small-diameter modules are recommended. Currently, no specific fouling index exists for LMWOC fouling. Hydrophobic membranes, such as polyamide, are proposed as alternatives to the standard silt density index (SDI) filter. Once LMWOC fouling potential is assessed, suitable pretreatment methods can be implemented. These include adsorbents, specialized water filters, oxidative decomposition, and antifoulants. In situations where pretreatment is impractical, alternative strategies like high pH operation might be considered. Membrane cleaning becomes necessary upon fouling; however, standard cleaning often fails to fully restore the original flow. Specialized CIP chemicals, including organic solvent-based and oxidative agents, are required. Conversely, LMWOC fouling typically leads to a stabilized flow rate reduction rather than a continuous decline. Aggressive cleaning may be avoided if the resulting operating pressure increase is acceptable. When a significant flow rate drop occurs and LMWOC fouling is suspected, analysis of the fouled membrane is necessary for identification. Standard FT-IR often fails to detect LMWOCs. Solvent extraction followed by GC-MS is required. Pyrolysis GC-MS, which eliminates the extraction step, shows promise. The review concludes by examining how LMWOCs can be strategically utilized to enhance membrane rejection and restore deteriorated membranes.
污垢，尤其是有机污垢和生物污垢，在反渗透/纳滤处理边际水（特别是废水）时构成了重大挑战。本综述的第1部分详细介绍了低分子量有机化合物（LMWOC）的污垢形成机制。第2部分重点关注应对措施和应用。有效的污垢预防依赖于预处理、早期检测、清洗、优化运行以及原位膜改性。准确的污垢预测至关重要。建议使用平板膜或小直径组件进行初步测试。目前，尚无针对LMWOC污垢的特定污垢指数。有人提议使用疏水性膜，如聚酰胺，作为标准淤泥密度指数（SDI）过滤器的替代品。一旦评估了LMWOC的污垢潜力，就可以实施合适的预处理方法。这些方法包括吸附剂、专用水过滤器、氧化分解和防污剂。在预处理不可行的情况下，可以考虑采用高pH值运行等替代策略。污垢形成后，膜清洗就变得必要；然而，标准清洗往往无法完全恢复原来的通量。需要使用专门的化学清洗药剂，包括基于有机溶剂的药剂和氧化剂。相反，LMWOC污垢通常会导致通量稳定下降，而不是持续下降。如果由此导致的操作压力增加是可以接受的，则可以避免过度清洗。当通量显著下降且怀疑是LMWOC污垢时，有必要对污染的膜进行分析以进行识别。标准的傅里叶变换红外光谱（FT-IR）通常无法检测到LMWOC。需要先进行溶剂萃取，然后进行气相色谱-质谱联用（GC-MS）分析。无需萃取步骤的热解气相色谱-质谱联用（Pyrolysis GC-MS）显示出了应用前景。综述最后探讨了如何战略性地利用LMWOC来提高膜截留率并修复性能恶化的膜。
