Membrane fouling control in the integrated process of magnetic anion exchange and ultrafiltration

Magnetic anion exchange (MIEX) has been increasingly concerned owing to its excellent performance for the removal of dissolved organic carbon in the treatment of drinking water. In this study, the ability of ultrafiltration (UF) membrane fouling control was analyzed by different combination processes of MIEX-UF. A single cycle and multi-cycle operations were conducted, and the separated and integrated processes of MIEX-UF were compared. Membrane filtration resistance, removal of organics, and morphologies of the membrane surface were analyzed. The results of the short-term operation did not show any obvious improvement in the membrane fouling control in the separated process (compared to UF alone); however, a marked improvement was obtained in the integrated process. The membrane filtration resistance analysis showed that the cake resistance (Rc) and pore blocking resistance (Rp) in the integrated process were only 52 and 24% of the values in the separated process. The multi-cycle operation demonstrated that the cumulative rate of hydraulically irreversible fouling was 0.0021 in the integrated process and was much lower than that in the separated process (0.0182). The mechanistic analysis shows that in the integrated process, a dynamic layer was formed on the membrane surface by the deposited MIEX beads, which markedly decreased the accumulation of the membrane foulants on the membrane surface and in the membrane pores.磁性阴离子交换树脂（Magnetic anion exchange, MIEX）因其在饮用水处理中去除溶解性有机碳的优异性能，日益受到学界关注。本研究针对MIEX-UF不同组合工艺的膜污染控制能力展开分析。实验设置了单周期与多周期运行模式，并对比了MIEX-UF的分置式与一体式工艺。分别从膜过滤阻力、有机物去除效果以及膜表面形貌三个维度进行表征分析。短期运行结果显示，分置式工艺的膜污染控制效果相较于单独超滤（Ultrafiltration, UF）工艺未展现出显著提升；而一体式工艺则实现了显著改善。膜过滤阻力分析表明，一体式工艺的滤饼阻力（Rc）与孔堵塞阻力（Rp）仅为分置式工艺的52%与24%。多周期运行结果显示，一体式工艺的水力不可逆污染累积速率为0.0021，远低于分置式工艺的0.0182。机理分析揭示，在一体式工艺中，沉积的MIEX微球会在膜表面形成动态截留层，显著减少膜污染物在膜表面及膜孔内的累积。