As space missions extend in duration and distance, there is an increasing need for autonomous life-support
systems capable of recycling resources and producing essential compounds in situ. In this context, alginateentrapped
microalgae were used to assess growth under reduced liquid conditions, testing two different
beads-to-volume ratios (1:1 and 1:2). In batch cultures conducted in flasks without aeration, the immobilized
microalgae using HEPES-Acetate-Phosphate (HAP) medium reached a maximum dry weight (DW) of
0.93 ± 0.03 g/L and 33.65 ± 1.19 x 10^6 cells/mL in the 1:2 configuration, compared to 1.01 ± 0.02 g/L and
37.44 ± 1.56 x 10^6 cells/mL in suspension. Biomass productivity peaked at 404 mg/(L⋅d) for suspension and
240 mg/(L⋅d) for 1:2 immobilized cultures. Biochemical analysis of immobilized biomass revealed high nutritional
value, with up to 32.5 % DW lipids, 23.6 % DW proteins, and 12.5 % DW carbohydrates. In the preprototype
column reactor with medium recirculation and air bubbling, microalgae showed lower productivity
than in batch tests indicating the need for further optimization of process configuration. Immobilized Chlorella
vulgaris offers a trade-off between reduced productivity and engineering advantages, such as ease of recovery.
