Evaluation of Photobioreactor Designs for Potential Application as Microalgal Façade Systems

Abstract

This study introduces innovative PBRs to optimize the growth of Chlorella vulgaris. For the first time, various designs, including flat and column PBRs with and without innovative interior structures, were investigated in the context of a Green Campus case study. The novel column PBR equipped with a spiral baffle significantly improved the homogeneity of the culture medium, enhancing light penetration, nutrient distribution, and gas exchange, while effectively reducing air bubble coalescence using an innovative spiral apparatus, achieving a biomass yield of 1.8 g L- 1 with a climate change impact of 0.93 kg CO2-eq. Furthermore, the integrated spiral apparatus simplified the harvesting, reducing operational complexities, overall cost, and potentially, CO2 emissions. Finally, the Life Cycle Assessment (LCA) was conducted to highlight the column PBR's environmental impact. The electricity used during the cultivation stage was responsible for almost all CO2 production. This hotspot is further discussed, as well as insights into ways to reduce the carbon footprint in future. The study encourages the integration of microalgal PBRs into urban bio-façade systems, aligning with global sustainability initiatives such as the European Green Deal. It offers insights into advanced façade design principles, emphasizing higher efficiency. Areas for future research include exploring different microalgae species and optimizing design parameters based on these findings.