Efficiency of CO2 fixation by microalgae in a closed raceway pond

Area of Science:

• Biotechnology
• Environmental Science
• Chemical Engineering

Background:

• Microalgae cultivation is a promising method for biomass production, but requires substantial carbon dioxide (CO2).
• Low CO2 fixation efficiency in open systems leads to high CO2 expenditure and increased cultivation costs.
• Efficient CO2 supply and retention are critical for cost-effective, large-scale microalgal cultivation.

Purpose of the Study:

• To investigate CO2 gas-liquid mass transfer and fixation efficiency in a novel closed raceway pond system.
• To develop a model for predicting CO2 fixation by microalgae under controlled conditions.
• To assess the impact of a transparent cover on CO2 retention and microalgal CO2 utilization.

Main Methods:

• Construction of a closed raceway pond by covering an open system with a transparent lid.
• Measurement of CO2 gas-liquid mass transfer coefficients.
• Development and application of a mathematical model for CO2 fixation.
• Investigation of microalgal CO2 fixation efficiency under intermittent gas sparging.

Main Results:

• The closed raceway pond design effectively prevents CO2 escape, increasing its retention time.
• CO2 fixation efficiency by microalgae reached up to 95% under optimized conditions with intermittent gas sparging.
• The developed model accurately predicts CO2 fixation, aiding in system optimization.

Conclusions:

• The closed raceway pond system offers a significant improvement in CO2 utilization efficiency for microalgal cultivation.
• This technology has the potential to reduce the cost of CO2 supply for large-scale biomass production.
• Optimized CO2 delivery, like intermittent sparging, is key to maximizing fixation rates in closed systems.