Developing a three-dimensional tangential swirl plate photobioreactor to enhance mass transfer and flashlight effect for microalgal CO2 fixation

A novel three-dimensional tangential swirl plate (TTSP) photobioreactor was proposed to strengthen flow perpendicular to central cross-section between two side walls, resulting in more widespread turbulence for improving microalgal CO2 fixation. The axes of four center-symmetrically arranged nozzles were tangential to a horizontal cylinder to form two staggered vortexes. When angle h between nozzle axis and central cross-section increased from 0 degrees to 22.1 degrees and then to 40.0 degrees, mixing time and average bubble diameter first decreased to the minimum (16.55 s and 0.57 mm) and then increased. When relative diameter of tangential cylinder d/D increased from 0.11 to 0.34 and then to 0.56, flashlight frequency and light time ratio first increased to the maximum (0.21 Hz and 42.8%) and then decreased. Accordingly, flashlight frequency was 90.9% higher in TTSP photobioreactor than that in two-dimensional jet-aerated tangential swirl plate (JTSP) photobioreactor, leading to an increase in microalgal CO2 fixation rate by 30%. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The novel three-dimensional tangential swirl plate (TTSP) photobioreactor enhances flow perpendicular to the central cross-section, leading to improved microalgal CO2 fixation efficiency. By adjusting the angle and relative diameter, factors such as mixing time, bubble diameter, flashlight frequency, and light time ratio can be controlled to optimize conditions for photosynthetic growth.