Towards Zero-CO₂-Emission Microalgal Cultivation: Optimized Carbon Feeding Enhances Biomass and Carbon Capture Efficiency

These data illustrate the calculation framework employed to define a daily gradient-based 2-h NaHCO₃ feeding policy as a function of the dynamically evolving biomass concentration, and its subsequent refinement to a 15-min interval strategy, aiming to minimize carbon losses and maximize biomass productivity in Haematococcus pluvialis cultures grown in a 3 L photobioreactor. Specifically, the fed-batch policy at 2-h intervals was developed based on experimental data of biomass production and carbon sequestration under carbon-sufficient conditions (continuous 0.5 % and 1 % CO₂ supply during photosynthetic cycles). By linking the specific growth rate (μ) with total biomass concentration (TB) and the utilized carbon (UC) with produced biomass (PB), a biomass-dependent daily carbon demand was determined, which subsequently distributed into 2-h feeding intervals. The minimum carbon dosage was calculated considering the decrease in dissolved carbon concentration due to the dissociation of NaHCO₃ and the associated CO₂ release. Finally, based on biomass production and carbon sequestration under the 2-h feeding policy, a 15-min NaHCO₃ feeding strategy was developed, re-evaluating the carbon doses, resulting in improved synchronization between carbon supply and cellular uptake and reduced CO₂ losses.