In the technical design of the processing technique and the test apparatus, the main aim is to generate the desired flow fields in order to realize the rolling and collisional effects necessary for the formation of pellet flocs. This is achieved by selecting an appropriate stirrer-vessel system and identification of the optimum process conditions. The design principle of the pre-treatment technique as a technical proof of concept is based on shear-assisted phase separation using turbulent vortex flow within a rotor-stator cavity. The stream pattern of the turbulent flow and its effect on the pre-treatment process was observed both visually and with the aid of a digital camera. The hydrodynamics and the vortex pattern in both reactors were investigated experimentally using PIV technique. A description of the flow filed and vortex pattern provides a better understanding of the hydrodynamics in terms of the magnitude and distribution of the averaged velocity vector and vorticity in the observation field.