Force Balance of Particles in Water During Ultrafiltration Membrane Process

Abstract

Membrane filtration is vital in our daily lives to extract fresh water from contaminated water. However, membrane filtration is suffering from fouling, which is induced by accumulations of particles on membrane surface. Due to the hydraulic field and electrical field (from functional groups of membranes) near membrane surface, particle will be exerted by different forces. The intermolecular forces such as the Lateral lift force, Brownian force, shear-induced force, Van Der Waal force and electrostatic repulsion force may affect the fouling process, and the water flux inside the system cab exert permeance drag force to the particles near the surface of membrane. In order to figure out the forces that may affect the filtration process, a model was established about the filtration process. In the model, the velocities of the each forces are listed and calculated in this paper. From the analysis, the relations between the particle velocities, which represents the filtration efficiency, and the forces, such as lift or shear forces, are well illustrated. This article shows the importance of potentially understanding the fouling process and providing insight of fouling mitigation for the membrane filtration process.