Development a novel hexagonal airlift flat plate photobioreactor for the improvement of microalgae growth that simultaneously enhance CO2 bio-fixation and wastewater treatment

A novel hexagonal airlift flat plate (HAFP) photobioreactor was designed to improve microalgae growth rate and compared with traditional flat plate (TFP) photobioreactor. The computational fluid dynamics (CFD) simulation was used to determine hydrodynamic parameters and optimal aeration rate in the photobioreactors. Additionally, the capability of the HAFP photobioreactor to enhance microalgae based CO2 bio-fixation and wastewater treatment were investigated. The results of CFD simulation indicated that the HAFP photobioreactor could improve hydrodynamic parameters of turbulence kinetic energy (TKE), average fluid velocity, dead zone (DZ), and water shear stress (WSS) up to 78 %, 41 %, 44 % and 40 %, respectively, under optimal aeration rate of 0.6 vvm. The proposed HAFP photobioreactor showed a drastic improvement in microalgae growth (up to 61 %). The maximum CO2 removal of 53.8 % and bio-fixation of 0.85 g L-1 d(-1) were achieved in the HAFP photobioreactor which were approximately 70 % more than that in the TFP photobioreactor. The results suggested that the HAFP photobioreactor could accelerate nutrients removal and achieve remarkably higher efficiencies of 91 %, 99 %, 97 % and 93 % of ammonia (NH3), nitrate (NO3-), phosphate (PO43-) and chemical oxygen demand (COD) within seven days of cultivation.

Automated summary

The novel hexagonal airlift flat plate photobioreactor showed significant improvements in hydrodynamic parameters, microalgae growth rate, and CO2 bio-fixation efficiency. It also exhibited high efficiency in wastewater treatment and nutrient removal.