Aerated stirred tank reactors are widely used in chemical and pharmaceutical industry in which mass transport and mixing time are among the most important parameters. Despite their importance, the prediction of theses parameters is still challenging due to large differences of the hydrodynamic inhomogeneities between lab scale and industrial scale. This thesis focuses on the measurement of these inhomogeneities and their influence on the important process parameters. In order to determine the differences to industrial processes, a transparent stirred tank reactor on industrial scale has been erected at the Hamburg University of Technology.