Effect of surface-patterned topographies of ceramic membranes on the filtration of activated sludge and their interaction with different particle sizes

The main benefits of surface patterning on filtration membranes are two-fold: (1) surface patterns increase the effective filtration area, and (2) enhance the back diffusion of foulants to minimise membrane fouling. Although the influence of pattern sizes has been revealed, the relationship between pattern sizes and foulant particle sizes has not been systematically studied. In this study, we fabricated ceramic membranes with line patterns of various designed topographies through 3D printing and investigated their differences in fouling alleviation with activated sludge and 5 latex particle sizes with narrow size distributions. Combinations of three pattern heights (h = 80, 120, 250 mu m) and three pattern spacings (s = 200, 500, 1000 mu m) were prepared in this study. Membrane fouling rates were affected by the topography, even after accounting for differences in the effective surface areas. Structures with high height (Pattern HM) performed poorly and had the highest fouling rate in activated sludge filtration compared to the rest of the patterns. The average rate of transmembrane pressure increase for HM was 2.48 +/- 0.07 kPa/min, 3 times higher than that of the best performing design (Pattern MM). The same phenomenon was observed for monodispersed latex microspheres. Moreover, we found that the fouling rate varied with h, s and particle size (a) and increased with a/(s/h) ratio. For the activated sludge and range of latex particles tested, a combination of h = 120 mu m and s = 500 mu m (Pattern MM) was the overall best design for fouling alleviation. Our findings provide an effective pathway to achieve maximum benefits of the surface-patterned ceramic membrane according to particle sizes, e.g., the s/h ratio must be designed to increase for the treatment of larger particles.

Automated summary

Surface patterning on filtration membranes provides benefits of increasing effective filtration area and enhancing back diffusion of foulants. This study investigates the relationship between pattern sizes and foulant particle sizes, and finds that the performance of ceramic membranes with different topographies varies in fouling alleviation. The best design for fouling alleviation is a combination of h = 120 μm and s = 500 μm.