Microalgal biotechnology for greenhouse gas control: Carbon dioxide fixation by Spirulina sp. at different diffusers

The carbon dioxide (CO2) emissions from fossil fuels contributes to global warming. This phenomenon became a major political issue in the fields of science, environment, and economy in current years. Microalgae can convert CO2 into biomass and oxygen through the photosynthesis. The aim of this study was to evaluate the influence of diffusers configuration and CO2 flow rate in mass transfer, CO2 fixation efficiency by Spirulina and in the biomass composition produced. Two flow rates (0.05 and 0.3 vvm) and four diffusers (sintered stone (SS), porous curtain (PC), perforated ring (PR) and porous wood (PW)) were used in this study. The maximum CO2 mass transfer coefficient (123.2 h−1) in the CO2-H2O system corresponded to the higher flow rate (0.3 vvm) using the diffuser porous curtain (PC). The maximum biomass productivity (125.9 ± 5.3 mg L−1 d−1) was observed for PC with a flow rate of 0.05 vvm. Increasing the flow rate (0.3 vvm) with PC resulted in a 26% increase in the carbohydrate content in biomass. The results showed a smaller flow rate with porous diffusers might promote an increase in CO2 fixation efficiency by microalgae.