煤基多孔炭膜去除压载水中微藻的研究

针对船舶压载水转移所引起的外来生物入侵问题, 开发了以廉价煤为原料经挤压成型、炭化等工艺制备出煤基管状多孔炭膜。分别采用扫描电镜和气体泡压技术对煤基炭膜的微观形貌和孔结构特性进行表征, 并详细考察了压载水处理过程中微藻种类、跨膜压差、错流速率以及微藻密度对处理效果的影响。实验结果表明, 煤基炭膜表面光滑, 孔隙结构发达, 孔径均一, 这非常有利于处理压载水中微藻。压载水中微藻尺寸越大, 膜的稳定通量越小; 增大跨膜压差, 膜的稳定通量增幅变缓, 尤其对含有小球藻和叉鞭金藻的模拟压载水, 因其尺寸与炭膜平均孔径相近, 容易受压变形进入膜孔形成膜内污染, 变缓程度更为明显; 增大错流流速可增大膜表面剪切力, 减少微藻在膜表面堆积, 提高炭膜的稳定通量; 提高藻液密度, 加重膜表面污染, 降低膜的稳定通量。经炭膜处理后, 渗透液中均未检出微藻的存在, 显示出煤基多孔炭膜在船舶压载水处理领域具有潜在的应用前景。

Removal of Microalgae in Ballast Water by Coal-based Porous Carbon Membrane

Introduction of invasive species via ballast water has been identified as one of the greatest threats to oceans. The coal-based porous carbon membrane with low cost for removal of microalgae in ballast water was prepared by carbonization of tubular carbonaceous precursor obtained by extrusion method. Scanning electron microscopy and bubble-pressure method were employed to investigate the morphology and pore structure characteristics of carbon membrane. Effects of microalgae size, transmembrane pressure and crossflow velocity on the steady-state flux were also studied. The results indicate that the as-prepared carbon membrane has smooth surface, rich and uniform porous structure, which are beneficial for removing microalgae in ballast water. A decrease in steady-state flux is observed as the microalgae size increases. High transmembrane pressure is more prone to block the membrane pore and results in the decrease of the steady-state flux. High crossflow velocity is favorable to increase the steady-state flux owing to the inhibition of fouling layer development through the high shear stress on membrane surface. After being treated by coal-based carbon membrane, no microalgae are detected. It indicates that coal-based carbon membrane is of great potential to ballast water treatment.