Conceptual Interpretation of Infiltration Under Sealing Process by Membrane Fouling Models

In the paper, the filtration membrane fouling models (Hermia, J.: Constant pressure blocking filtration laws-application to power law non-newtonian fluids, Trans. of the Institution of Chemical Engineers, 60,183–187. (1982).; Bolton, G., Kuriyel, R., LaCasse, D.: Combined models of membrane fouling: development and application to microfiltration and ultrafiltration of biological fluids, Journal of Membrane Science, 277, pag. 75–84 (2006).;), adapted to simulate the infiltration of overland flow through porous soils under seal formation, were tested. The validation dataset, provided by the SERLAB (Soil Erosion LABoratory, Italy), consists of runoff and infiltration rates measured at 5 min intervals in a sequence of four simulated rainfall (70 mm/h intensity), following initial tillage and lasting until the steady runoff is reached. As a porous medium, the soil is assumed to be the filter. The soil infilling that occurs during structural seal formation is assimilated to the membrane fouling process, and the turbid fluid is the flow enriched in fine particles due to the illuviation of the soil particles detached by raindrop impact and overland flow. The combination of two basic models, intermediate pore blocking (IPB) and standard pore blocking (SPB), yields the best fit. IPB brings about progressive superficial pore clogging and particle accumulation at the surface; in SPB, the particles illuviated by water accumulate inside the media on the walls of straight cylindrical pores. The results indicate the efficacy of models able to simulate multiple mechanisms participating in the structural modification of soil. Also, IPB model alone, contrary to SPB, provides reasonable estimates. This indicates that the dynamics of the soil surface hydrological properties remain active. At the same time, the pore constriction seems to run out quickly with the cumulative infiltration from tillage.