A novel arrayed tangential-circular jet swirling plate photobioreactor for enhancing the flashing light effect to promote microalgal growth and CO2 fixation.

A novel arrayed tangential-circular jet swirling plate photobioreactor (ATCJSP) was developed to promote microalgal growth and carbon fixation by enhancing the flashing light effect, improving mass transfer and mixing, and reducing bubble diameter. In this system, the microalgae solution was injected through four symmetrically arranged nozzle sets with four nozzles in each set to create vortices parallel to the light path. These vortex arrays collectively drove an efficient spiral flow, which accelerated the light-dark cycle of the microalgae cells and strengthened gas-liquid mass transfer. Under optimal structural parameters (relative tangential circle diameter = 0.3, 4 nozzle sets, inlet velocity = 1.59 m s-1), the ATCJSP significantly outperformed the conventional airlift flat-plate photobioreactor (AFPP). Specifically, it increased the light-dark cycle frequency by 46.5 times, reduced bubble diameter by 64.7%, enhanced the mass transfer coefficient by 7.17 times, and shortened the mixing time by 65.43%. Furthermore, the flow dead zones were reduced by 78.12%. These improvements resulted in a 63% increase in biomass dry weight and a 75% increase in the average CO2 fixation rate. Consequently, this novel vortex-driven design provides a highly efficient, scalable, and robust strategy for industrial microalgal cultivation and biological carbon mitigation.