Drinking Water Treatment Unit Processes: Computational Fluid Dynamics Modeling

Abstract

Abstract The conventional drinking water treatment plant train of unit processes includes an intake structure, rapid mix, flocculation, sedimentation, granular media filtration, disinfection, and distribution. As populations grow and unconventional sources of water are sought, alternative unit processes are becoming more common, such as ozonation and reverse osmosis. Novel ideas to accomplish certain goals in the treatment plant have resulted in modified processes that function differently than their conventional counterparts; static mixers are one example. With this changing landscape of drinking water treatment, it behooves engineers to use modern tools to compare options and optimize their designs. Computational fluid dynamics (CFD) modeling is a method for accomplishing those goals. This article discusses CFD modeling in the context of the above drinking water treatment plant unit processes. The most common software packages are discussed, including ANSYS Fluent, COMSOL Multiphysics, and OpenFOAM. With each unit process, the goals of CFD modeling are explored. Some common threads emerge among processes, such as the utility of identifying dead zones or eddies in vessels and the importance of calculating shear and mixing intensity. This article thus serves as an overview for practitioners or others interested in using CFD as a drinking‐water treatment plant design tool.