The knowledge on the hydrodynamic property and mass transfer of bubbles is important since it will give guidelines for selecting the operation condition and for reactor design in such processes. For this purpose, this PhD manuscript has implemented an experimental investigation of single air bubbles rising in various polymer solutions (Breox, Polyacrylamide (PAAm) and Xanthan gum) which can simulate the property of the sewage. The works can divided into three parts: Firstly, with a review of the current visualization techniques for mass transfer, three techniques have been tested for air bubble (equivalent diameter ≈ 1 mm) rising in water including traditional Planar Laser Induced Fluorescent (PLIF, dye: fluorescent resorufin), Fluorescent quenching technique (PLIF with Inhibition, dye: ruthenium complex) and colorimetric techniques (dye: pink resorufin), respectively. Secondly, based on images captured by a high speed camera, the hydrodynamics of the bubble single air bubbles (equivalent diameters: 0.7-7 mm) rising in the polymer solutions (PAAm and Xanthan) have been investigated including the bubble velocity, trajectory and bubble shape. Finally, based on PLIF-I technique, the mass transfer and diffusion phenomena in the wake of single air bubbles (equivalent diameter ≈ 1 mm) rising in various aqueous polymer solutions (PAAm and Breox) are investigated.