Hydrodynamic and mass transfer characterization of a flat-panel airlift photobioreactor with high light path

Aeration and mass transfer optimization in a rectangular airlift loop photobioreactor for the production of microalgae

“…It is shown that at the normal operating condition (i.e., the superficial gas velocity of 8.3  10 À4 m/s and 4.2  10 À3 m/s in this work and Reyna-Velarde et al (2010), respectively), the power supply in this work (about 8 W/m 3 ) is only a quarter of that in Reyna-Velarde et al (2010). In addition, the energy consumption is only one-sixth or one-ninth of the current operating guidelines (50-70 W/m 3 ) in the bubble column and the ALRs (Béchet et al, 2013;Kumar et al, 2011;Lehr and Posten, 2009;Singh and Sharma, 2012), and it compares favorably with 7.5 W/m 3 obtained in a cylindrical column reactor with a long height (2 m height  0.19 m internal diameter) (Béchet et al, 2013).…”

“…6, and an example of RALPBR with one riser and one downcomer provided by Reyna-Velarde et al (2010) is also illustrated here for comparison. It shows that the mass transfer coefficient in this work is an order of magnitude higher than that of Reyna-Velarde et al (2010) at the same superficial gas velocity due to the produced small bubbles (Sauter mean diameter d 32 in this reactor is about 2.5-3.25 mm). Since the superficial gas velocity is low, a highly efficient RALPBR with high performance of mass transfer and low power supply is obtained.…”

“…Before selecting a specific type, one should take many factors into consideration, for instance, characteristics of PBRs, operating costs, maintenance and cleaning, and so on. A RALPBR split in the direction of light path with one riser and one downcomer has been widely adopted to enhance the radial mixing (Reyna-Velarde et al, 2010), however the light depth is low and costs of operation, maintenance and cleaning are high for a long run. Furthermore, some of the light may be blocked by the baffle in these PBRs.…”

“…The RALPBR can be classified into three categories according to the geometric structures, i.e., a riser and a downcomer type (Reyna-Velarde et al, 2010), two risers and a downcomer type (Kilonzo et al, 2006), and a riser and two downcomers type (Yu et al, 2009). Before selecting a specific type, one should take many factors into consideration, for instance, characteristics of PBRs, operating costs, maintenance and cleaning, and so on.…”

Industrial Cultivation Systems for Intensive Production of Microalgae

“…The light/dark cycle was also accomplished in flat airlift configurations where the riser was the photic zone [92,93]. However, the mixing times were only a few seconds and advantages in the photosynthesis rate were often not observed.…”