Modelling of hydrodynamics, light distribution and growth in algal photo-bioreactors
Mathematical modelling and computer simulations are viable tools for analysing and optimizing the performance of photo-bioreactors (PBRs). On an empiric level, simple models of algal growth related to external irradiance and culture density can be used for interpretation of data sets, investigation of scale-up, estimation of maximal productivity, and comparison of different PBRs (Schreiber et al. 2017).
On a more fundamental level, several models need to be combined for describing the relevant physical phenomena, in particular movement of the liquid and cells in the reactor, solubility and distribution of gases, scattering and absorption of light.
We focus on computational fluid dynamics (CFD) combined with algal particle tracing to obtain the characteristics of algae movement in the PBR. The distribution of light inside the reactor is calculated by numerically solving the radiative transfer equation. Together with the traces of algal cells, this enables estimation of the dynamic light experienced by the algal cells (Loomba et al. 2018), and subsequently determination of the growth history of single algal cells. In this workflow the impact of relevant parameters (reactor shape, gas flow properties, light input, algae properties) on algal growth can be determined.
The final aim is to support the identification of optimal operating conditions for algae cultivation in PBRs in order to maximize productivity.
C. Schreiber, D. Behrendt, G. Huber, C. Pfaff, J. Widzgowski, et al. (2017), Growth of algal biomass in laboratory and in large-scale algal photobioreactors in the temperate climate of western Germany. Bioresource Technology 234: 140-9.
V. Loomba, G. Huber, E. von Lieres (2018) Single‑cell computational analysis of light harvesting in a flat‑panel photo‑bioreactor. Biotechnology for Biofuels 11:149.