From 2010 to 2013, I worked on the characterization of mass transfer and hydrodynamics in the wake of bubbles in wastewaters.
For wastewater treatment (e.g. in activated sludge or membrane bioreactors), a supply of dissolved oxygen, e.g. by injecting air bubbles, is required to ensure the availability of microorganisms able to degrade specific pollutants. However the mechanisms of gas transfer from the bubble to the microorganism in such complex media is still poorly understood. The purpose of this work co-funded by SUEZ-Degremontwas to locally visualize the impact of the liquid composition on these two phenomena (mass transfer & hydrodynamics) in the wake of oxygen bubbles. Visualization techniques involved for this study include PLIF (Planar Laser Induced Fluorescence) and PIV (Particle Image Velocimetry). Please refer to the Techniques section for further details. One of the main outcomes is a better understanding of the impact of surfactants, which is of prime importance since massively encountered in wasterwater due to their daily use for all washing purposes.
Evolution of the oxygen concentration fields in the wake of a bubble as in DI water and in filtered wastewater after and without treatment
Contamination angle of an oxygen bubble rising in DI water and DI water+surfactant