Multi-scale growth modeling of C. reinhardtii and N. oculata: from microplates to pilot photobioreactors

Microalgae cultivation for sustainable biotechnology applications requires reliable scale-up from laboratory to industrial photobioreactors. The transition from small-scale optimization to commercial production remains a major bottleneck, as growth kinetics established in controlled laboratory conditions frequently do not translate predictably to larger cultivation systems. Predicting microalgal growth across scales is therefore crucial for designing efficient photobioreactors and accelerating deployment of algae-based bioprocesses. In this work, C. reinhardtii and N. oculata was quantified across diverse volumes and conditions to address this scale-up challenge. C. reinhardtii was grown in lab-scale experiments while N. oculata was cultivated in reactors from 1L to 285 L with different geometries. This dataset enables investigation of how growth dynamics and kinetic parameters scale with culture volume and reactor type. To capture growth dynamics across environments, different models were investigated in this work: Monod-type, logistic, and hybrid formulations on this dataset. For C. reinhardtii, 25 combinations of light and nutrient availability revealed clear regimes of photo-limitation, photo-inhibition, and nutrient limitation. This systematic evaluation highlighted: 1) which models best represented growth under diverse conditions at a specific scale and 2) how kinetic parameters scale in regards with reactor geometry and volume. This study demonstrates that high-throughput laboratory measurements can be linked to pilot-scale cultivation via mathematical modeling, providing a framework for scalable microalgal bioprocess design relevant to both research and sustainable biotechnology.