Chapter 4 - Mechanisms of Particle Deposition

Abstract

This chapter explores the mechanisms of particle deposition. The major mechanisms for particle deposition from suspension flowing through granular media are inertial impaction, interception, sedimentation, electrostatic forces, Brownian diffusion, and straining. In addition, deposition may also result from chemotaxis and detachment (in a negative sense). Using the media representation methods described, this chapter discusses the manner by which these mechanisms function and derive the collector efficiencies due to these mechanisms. This chapter examines the six most common particle–transport mechanisms found in granular filtration. Assuming that in the area near the collector surface, the collector–particle interaction is favorable, the flux of particle transport and that of deposition are the same. The discussion presented here leads to derive the collector efficiencies attributable to each of these mechanisms. Finally, the last section of the chapter presents a brief discussion of the particle detachment and provides some of the recent relevant literature. In granular filtration, particles deposited on filter grain surfaces may become detached and re-entrained by the flowing suspension as the flow condition changes. The difference between the deposition rate and that of detachment is the net rate of filtration.