Keywords: computational fluid dynamics, CFD, dissolved air flotation, DAF, large bubbles, modelling, multiphase models, water pollution, environmental pollution, flow patterns, wastewater treatment, flow rate
Two-phase simulations of an off-nominally operating dissolved-air flotation tank
The flow patterns of the contaminated water and the air bubbles inside a large-scale Dissolved Air Flotation (DAF) tank were examined using CFD modelling. The DAF tank was operating off-nominally in the sense that it was supplied with bubbles larger than originally designed for. Attention was drawn to the location for air injection and the effect of having more than one-size bubbles in the tank, regarding the good contact between phases and the subsequent bubble recovery at the tank free surface. The role of the inclination of the internal baffle of the tank and liquid flow rate was also examined.