This research highlights the importance of multiphase mixing processes operating at industrial scales and demonstrates some of the major challenges that can occur when designing these systems. There are two strands to this project; gas-liquid and structured liquid mixing systems, both involve examining mechanically agitated vessels by Electrical Resistance Tomography (ERT). This research investigates the gas liquid mixing system of air and water and structured liquid mixing systems for Newtonian and non-Newtonian fluids including shampoo, glucose, silicon oil, and water. The gas liquid mixing system examines the power data for two configurations, a 6 blade disk turbine (Rushton turbine) with a 6 Mixed flow down-pumping impeller and a 6 blade disk turbine with a 6 Mixed flow up-pumping impeller, at different agitation speeds and gas flow rates. For the first time, these set of agitator configurations are investigated at high superficial gas velocities, which allows studying the flow regimes at superficial gas velocities similar to industrial conditions. Gas hold-up is investigated with a new proposed correlation which works for the full range of superficial gas velocities. At these high superficial gas velocities, this report introduces a 3rd bubble class, as seen in dynamic gas disengagement experiments, which corresponds to very large slugs of gas. Mass transfer and mixing times have also been studied for higher gas flow rates, to explore how different the heterogeneous regime is from homogeneous regime. The second strand of this research project studies Newtonian and non-Newtonian fluids by an anchor device system. Effects of salt addition on viscosity have been tested for glucose and shampoo as well as mixing times using ERT. A graphical representation of Reynolds number versus mixing time is created using a range of fluids that fall into turbulent, laminar and transitional regime.