Innovative development of membrane sparger for carbon dioxide supply in microalgae cultures

Area of Science:

• Biotechnology
• Algal Biotechnology
• Bioprocess Engineering

Background:

• Efficient carbon dioxide (CO2) supply is crucial for optimizing microalgae cultivation.
• Conventional gas sparging methods can be inefficient and lead to gas loss.
• Spirulina sp. is a promising microalga for biomass and protein production.

Purpose of the Study:

• To develop and evaluate a membrane sparger (MS) integrated into a tubular photobioreactor.
• To enhance carbon dioxide (CO2) fixation and biomass production in Spirulina sp. LEB 18 cultures.
• To compare the efficiency of MS with conventional spargers for CO2 supply.

Main Methods:

• Integration of a membrane sparger (MS) into a tubular photobioreactor system.
• Cultivation of Spirulina sp. LEB 18 with CO2 supplied via MS.
• Comparison of key growth and physiological parameters against a control group using a conventional sparger.
• Analysis of dissolved inorganic carbon (DIC) concentrations, biomass yield, productivity, carbon content, CO2 fixation rate, and CO2 use efficiency.

Main Results:

• The MS system achieved the highest accumulated dissolved inorganic carbon (DIC) concentration (127.4 mg L⁻¹ d⁻¹).
• Significantly higher biomass concentration (1.98 g L⁻¹), biomass productivity (131.8 mg L⁻¹ d⁻¹), and CO2 fixation rate (231.6 mg L⁻¹ d⁻¹) were observed with MS.
• The MS system demonstrated superior CO2 use efficiency (80.5% w w⁻¹) compared to conventional sparging.
• Spirulina biomass consistently exhibited high protein content (64.9–69% w w⁻¹).

Conclusions:

• Membrane spargers represent an innovative and efficient system for carbon supply in microalgae cultivation.
• The MS technology enhances Spirulina biomass production and CO2 fixation rates.
• This approach offers potential for increased process efficiency and reduced biomass production costs.