Micro-bubble flow simulation of dissolved air flotation process for water treatment using computational fluid dynamics technique. (January 2020)

• Record Type: Journal Article
• Authors: Lee, Kyun Ho; Kim, Haedong; KuK, Jung Won; Chung, Jae Dong; Park, Sungsu; Kwon, Eilhann E.
• Is Part Of: Environmental pollution. Volume 256(2020)
• Publication Date: 2020-01
• Subjects: Dissolved air flotation -- Water treatment -- Computational Fluid Dynamics -- Two-phase flow -- Micro-bubble; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2019.01.011
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: A dissolved air flotation (DAF) system is one of the water treatment processes that purifies contaminants through a buoyancy effect by attaching the moiety of micro-bubbles on their free surface. Since the DAF system was first used in the drinking water treatment in the 1960s, it has been recognized as an effective treatment for the water purification process. Most previous works laid great emphasis on the internal flow behaviors of fluid to improve the purification efficiency of the DAF system. Nevertheless, the practical implementation with a pilot plant indeed revealed some technical incompleteness for the DAF system. To circumvent for the technical incompleteness, numerical simulation based on computational fluid dynamics (CFD) has been carried out to understand the in-depth knowledge on internal flow phenomena in the DAF system. However, the standard k - ε turbulence model has been conventionally used in the most studies without any proper consideration process. Accordingly, the objectives of this study were to investigate the major effects on the internal flow behaviors for an efficient numerical simulation of DAF when a different turbulence model and micro-bubble parameters are used. As a result, the present study found that the standard k - ε model would be not proper for the internal flow simulation of the DAF process and a careful consideration would be required for a more accurate prediction. In addition, the present study examined a desirable internal flow pattern with various operating conditions of the micro-bubble. Consequently, the main findings of this study are expected to provide realistic information to related researchers for designing the DAF system with the optimal operating parameters. Graphical abstract: Image 1 Highlights: CFD simulation is important for design optimization of DAF system. Appropriate turbulence model needs to be selected based on a verification process. Standard k - ε model shows unreasonable flow behaviors when used for DAF system. Effects of micro-bubble parameters can be validated using the CFD simulation.