Figure 3.9 shows the experimental setup for determining the microbubble rise velocity and liquid flow velocity in the ALB. The aeration method was used as the microbubble generator system. The microbubble is generated by supplying a steady air flow directly to the porous aerator in the fluid. The bubble rise velocity and the liquid flow velocity of the five bubble sizes in the ALB were measured. The ALB is filled with approximately 3 Litres of de-ionized water and the distance between the water level and the ceramic aerator surface is approximately 195 mm. At a given 0.1 l/min steady flow rate, 1020 µm, 910 µm, 755 µm, 690 µm and 440 µm bubbles were generated by the aerator with pore sizes of 150 µm, 50 µm, 20 µm, 16 µm and 2 µm respectively. In order to maintain a relatively constant condition, the inlet flow rate was controlled by using rotormeter and a pressure regulator was used to maintain a constant pressure for the system. The experimental condition is presented in Table 3.3. The operating pressure was caused by different as different pore size ceramic aerator. Therefore, a correction factor given by the manufacturer was applied to obtain require flow rate. Table 3.3: Experimental 3 Operating Conditions Airlift Bioreactor Geometry Inside diameter : 140mm : 260mm Height Diameter of draft tube : 84mm : 130mm Height of draft tube Ceramic Aerator Geometry : 55mm Inside diameter Area : 2375.83mm2 : 2-150 µm Pore diameter Operating Conditions : 0.1 l/min Gas Flow Rate : 0.05-1bar Operating Pressure : 20±1°C Water Temperature : 3 l Volume of water : 195mm Medium Height : Steady flow Flow condition
Figure 3.9 shows the experimental setup for determining the microbubble rise velocity and liquid flow velocity in the ALB. The aeration method was used as the microbubble generator system. The microbubble is generated by supplying a steady air flow directly to the porous aerator in the fluid. The bubble rise velocity and the liquid flow velocity of the five bubble sizes in the ALB were measured. The ALB is filled with approximately 3 Litres of de-ionized water and the distance between the water level and the ceramic aerator surface is approximately 195 mm. At a given 0.1 l/min steady flow rate, 1020 µm, 910 µm, 755 µm, 690 µm and 440 µm bubbles were generated by the aerator with pore sizes of 150 µm, 50 µm, 20 µm, 16 µm and 2 µm respectively. In order to maintain a relatively constant condition, the inlet flow rate was controlled by using rotormeter and a pressure regulator was used to maintain a constant pressure for the system. The experimental condition is presented in Table 3.3. The operating pressure was caused by different as different pore size ceramic aerator. Therefore, a correction factor given by the manufacturer was applied to obtain require flow rate. Table 3.3: Experimental 3 Operating Conditions Airlift Bioreactor Geometry Inside diameter : 140mm Height : 260mm Diameter of draft tube : 84mm Height of draft tube : 130mm Ceramic Aerator Geometry Inside diameter : 55mm Area : 2375.83mm2 Pore diameter : 2-150 µm Operating Conditions Gas Flow Rate : 0.1 l/min Operating Pressure : 0.05-1bar Water Temperature : 20±1°C Volume of water : 3 l Medium Height : 195mm Flow condition : Steady flow
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