In recent years, bubble columns with highly viscous liquids are found in widespread applications in chemical and biotechnological processes especially in biochemical reactors and pollution treatment. The aim of this work is to study the hydrodynamic characteristics in three-phase fluidized beds. The following phenomena were studied e.g. gas- holdup, bubble rise velocity, mean bubble diameter, bubble frequency, minimum fluidization velocity, superficial gas velocity and the physical and rheological properties of liquid phase. The experimental work of gas-liquid-solid fluidized beds system was...