Beyond CO₂: Incorporating Bicarbonate, Dynamic Carbon Speciation, and Stoichiometric Plasticity Into Algal Growth...

Area of Science:

• Biotechnology
• Environmental Science
• Chemical Engineering

Background:

• Biological carbon capture using algae is a promising strategy for mitigating atmospheric carbon emissions.
• Existing models often overlook the dynamic interactions of inorganic carbon species influencing algal growth.
• Understanding these dynamics is crucial for optimizing algal cultivation systems.

Purpose of the Study:

• To investigate and compare dynamic algal growth models based on inorganic carbon-limited specific growth rates.
• To evaluate models considering carbon dioxide (CO2), bicarbonate (HCO3-), and carbonate (CO32-) as potential substrates.
• To develop a framework for predicting algal growth and carbon speciation in cultivation systems.

Main Methods:

• Developed dynamic algal growth models incorporating inorganic carbon species conversion rates, not equilibrium.
• Included algal biomass stoichiometry accounting for nutrient-dependent plasticity.
• Compared 8 different Monod-based model equations against batch, closed reactor data.

Main Results:

• The model incorporating CO2 and HCO3- as substitutable substrates demonstrated the best fit with experimental data.
• This model accurately estimated total inorganic carbon concentrations, biomass, and pH.
• It outperformed other models in predicting algal responses under specific conditions.

Conclusions:

• The validated model provides a robust framework for predicting algal growth and carbon speciation.
• Informed design and operation of algal cultivation for carbon abatement and bioproducts.
• Highlights the importance of dynamic inorganic carbon speciation in algal growth models.