Department of Material Science and Engineering, Faculty of Engineering, National University of Singapore, Singapore 117574; State Key Laboratory of Materials-Oriented Chemical Engineering, National Engineering Research Center for Special Separation Membrane, Nanjing Tech University, Nanjing 210009, China.
Centre for Water Research, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576.
Water Res. 2022 Jul 15;220:118661. doi: 10.1016/j.watres.2022.118661. Epub 2022 May 24.
Rational design of cross-sectional microstructure in ceramic membranes has shown to improve membrane filtration efficacy without affecting rejection performance. In this work, we adopted 3D spray-coating technique to generate multi-layered membrane layers on macro-porous flat-sheet ceramic supports. The thickness of each layer was controlled by spray-coating cycles, and a gradient membrane layer was rationalized by successively coating three ceramic slurries containing alumina powders of gradually refined particle sizes, followed by co-sintering. Gradient membrane layers on both sides of the various sized flat-sheet ceramic supports were fabricated. Compared to the non-gradient counterpart, the gradient membranes showed both higher pure water flux (at the same TMP) and lower membrane resistance, which clearly evidenced the benefits of gradient profile in the membrane layer. Further, their performance in aerobic membrane bioreactors (AeMBR) was comparably studied for the first time. The treatment performance was not significantly affected by the types of membranes used, while the gradient membrane showed better filtration performance (i.e., a slower rise in TMP). Although the fouling mechanisms were revealed to be similar, the fouling layer in the gradient membrane was composed of a higher percentage of smaller foulants compared to that of the non-gradient counterpart. The observed differences were closely correlated to the larger internal pore structure in the gradient membrane. The present work provides a feasible 3D spray-coating technique for the fabrication of gradient flat-sheet ceramic membranes, and clarifies the benefits in AeMBR for domestic wastewater treatment.
陶瓷膜的横截面微观结构的合理设计已被证明可以提高膜过滤效果，而不会影响截留性能。在这项工作中，我们采用 3D 喷涂技术在大孔平板陶瓷载体上生成多层膜层。通过喷涂循环来控制每层的厚度，并通过依次涂覆三种含有氧化铝粉末的陶瓷浆料来合理化梯度膜层，这些浆料的粒径逐渐细化，然后进行共烧结。在各种尺寸的平板陶瓷载体的两侧都制造了梯度膜层。与非梯度膜相比，梯度膜在相同 TMP 下表现出更高的纯水通量和更低的膜阻力，这清楚地证明了膜层中梯度分布的优势。此外，这是首次在好氧膜生物反应器（AeMBR）中对它们的性能进行比较研究。处理性能不受所使用的膜类型的显著影响，而梯度膜表现出更好的过滤性能（即 TMP 上升较慢）。尽管发现的污垢机制相似，但与非梯度膜相比，梯度膜中的污垢层由更高比例的较小污垢组成。观察到的差异与梯度膜中较大的内部孔结构密切相关。本工作为梯度平板陶瓷膜的制备提供了一种可行的 3D 喷涂技术，并阐明了在 AeMBR 中用于处理生活污水的优势。
