Chapter 7 - Coagulation and Flocculation

Abstract

Chapter 7 introduces the theory of settling and highlights the practical applications for coagulation and flocculation. The classification of settling behavior is outlined, and the theory of ideal settling is explained. Class I represents unhindered settling of discrete particles. Class II indicates settling of a dilute suspension of flocculent particles. Hindered and zone settling are labeled as Class III. Finally, Class IV represents compression settling (compaction and consolidation). The settling velocity can be determined using either Stoke’s law or Newton’s law, depending on whether the flow past the particles is laminar or turbulent, respectively. Important colloidal suspensions and coagulation processes are also highlighted, and associated key coagulation chemicals are listed. The general operation of coagulation and flocculation processes and corresponding treatment units is outlined. The theory of rapid mixing and flocculation is explained using easy-to-understand language. After reading this chapter, the audience should appreciate coagulation and flocculation processes and associated treatment units.