Influence of Fresh Water on Microbubble Generation in an Airlift Column Applied to Aquaculture: Extraction Capacity

Abstract

Bubble flows consist a liquid phase and a gaseous phase dispersed as bubbles. They occur in nature and in many industrial applications, such as oil transportation in pipelines and steam generators for power generation. Due to large difference in density between gas and liquid, the flottability force causes bubbles to rise, which in turn can generate overall motion and agitation in liquid. This use of gravity as a flow driver, which is specific to disperse phase systems, is used in process engineering (bubble columns and gasosiphon) to sparingly promote mixing and exchange between gas and liquid. In many applications, bubbles are used to agitate a liquid in order to promote mixing and transfers. This work is devoted to study of hydrodynamics of a bubble column. Experimentally, we have determined properties fluctuations of velocities inside the aquarium of rising homogeneous bubbles for different bubble sizes and vacuum rates. The interfacial area between gas and liquid phase is a crucial factor for mass transfer in bubble columns. The molecular exchange between a given volume of gas and water can be enhanced by formation of smaller bubbles, leading to a larger gas-liquid interface. This work presents the various physical phenomena that apply to bubbles, as well as associated dimensionless numbers. A state art of Micro-Bubble Generators (MBG) is then presented, presenting systems using various phenomena such as cavitation, electrolysis, or shear.

Use of Nanobubbles to Improve Mass Transfer in Bioprocesses

“…Impact on Absorption Processes: The presence of nanobubbles can increase the masstransfer coefficients in the bubble absorption processes. However, determining the optimal nanobubble concentration is relevant, as low concentrations could be ineffective, whereas high concentrations could lead to counterproductive effects, such as saturation or blocking of transfer interfaces [57]. • Advances in Modeling and Simulation: To effectively address these challenges, masstransfer modeling in industrial and environmental settings has adopted advanced techniques, such as the Finite Element Method (FEM) and Control Volume Method (CVM).…”