Fouling Layer Surface Heterogeneity Improves Permeate Flux

In this research, we used modeling to assess the impact of irregular fouling-layer surface morphology (i.e., roughness) on permeate fluxes. Two membrane filtration models, each based on Darcy's Law, were used to predict fluxes for fouling layers with varying degrees of surface irregularity. One of the models considered the arithmetic mean thickness of the fouling layer, while the other accounted for the actual, irregular surface morphology assuming one-dimensional permeate flow. Surface morphology and permeate-flux data from an ultra-low pressure gravity-driven membrane filter were used to test the models. The models that accounted for the surface morphology were more accurate, especially for highly irregular surface morphologies. These models were also able to correctly predict greater permeate fluxes exhibited by highly irregular surface morphologies despite their having greater mean thicknesses. Our results show that models based on the mean thickness may not accurately characterize the effect of the fouling layer on fluxes. Future research should consider the surface morphology of the fouling layer when devising fouling mitigation strategies.