Rheology and Hydrodynamics of Algal and Cyanobacteria Co-Cultures
Description
Microalgae and cyanobacteria stand at the crossroads of sustainability and biotechnology, offering a unique opportunity to capture CO₂ while allowing to valorize produced biomass and/or biomolecules [1]. Algae biotechnology is rapidly expanding (projected 48 $B 2028 worldwide market – Source : GrandViewResearch), with numerous product application fields (biofuels, pigments, cosmetics, agriculture, food, pharmaceutics, hydrogen production). Critical challenges yet exist in supporting this industry’s growth and impact. In particular, scaling-up sustainable culture operations, making them viable as impactful CCUS technologies, ensuring high yield, large volume biomass production [2]. This eventually amounts to a better scientific understanding of 1) physico-chemistry of high biomass and active molecule concentrations, which renders suspensions non-Newtonian [3], [4], [5]; 2) large volumes and flow scales, which results in chaotic and/or turbulent flow processes; 3) optimized and efficient mixing and mass transfer operations, which requires efficient transfer intensification strategies. Co-cultures of microalgae and cyanobacteria perfectly embody those 3 challenges. They present great synergistical potential for efficient and productive growth of the combined species [6]. Yet at the same time these systems exhibit complex non-Newtonian rheology [3], [7] where microscopic interactions between cells and extracellular substances govern the macroscopic hydrodynamics, and ultimately process performance.
Bringing together complex fluid dynamics and algal biotechnology, this project aims to elucidate the coupled rheologicaland hydrodynamic mechanisms underlying co-cultures of microalgae and cyanobacteria, in order to ultimately establish predictive relationships between biological composition, flow stability, and transfer efficiency in controlled culture conditions. Building on first recent findings by the supervision team [3] and original experimental approaches, the research will develop advanced experimental and modelling frameworks to characterize and control these effects, combining precision rheometry [3], [4], [5], [8], high-resolution flow imaging (PIV, LIF) [9], [10], and hydrodynamics analysis [9], [11] in multiphase systems [9], [12], [13] to quantify the role of biology in rheology and flow behaviour.
Conducted jointly between IMT Nord Europe and its new key partner the University of Technology Sydney (UTS), the project will bridge fundamental rheophysics and bioprocess engineering, identifying how controlled instabilities and chaotic mixing can enhance productivity and energy efficiency in photobioreactors. Its outcomes will directly contribute to the design of energy-efficient, high-density algal cultivation systems, advancing both the fundamental understanding of complex fluids and the development of low-carbon biotechnologies aligned with global sustainability goals (Mostly SDG#9, #12, ramifications into #2, #6, #7, long-term impact in #13, EU 2040 Climate pathway). From an institutional standpoint, the project is expected to 1) strengthen the UTS-IMT International collaboration, in line with the recent agreements; 2) establish Complex Fluids Intensification activity [14] at IMT following the PI’s recent HDR [15]; 3) open technological transfer opportunities for those activities; 4) allow to continue working towards the CHyTriCS ERC project on chaotic transfer in complex fluids (2025 StG phase 2, 2027 resubmission).
Bibliography
Bibliography
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[6] D.-H. Kim, H.-S. Yun, Y.-S. Kim, and J.-G. Kim, “Effects of Co-culture on Improved Productivity and Bioresource for Microalgal Biomass Using the Floc-Forming Bacteria Melaminivora Jejuensis,” Front. Bioeng. Biotechnol., vol. 8, Dec. 2020, doi: 10.3389/fbioe.2020.588210.
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[8] C. Carré, M. Moazzen, T. Lacassagne, and S. A. Bahrani, “Elasto-inertial dissipation in particle-laden viscoelastic Taylor–Couette flow,” Journal of Fluid Mechanics, vol. 997, p. A19, Oct. 2024, doi:10.1017/jfm.2024.781.
[9] T. Lacassagne, M. EL Hajem, J.-Y. Champagne, and S. Simoëns, “Turbulent mass transfer near gas-liquid interfaces in water and shear-thinning dilute polymer solution,” International Journal of Heat and Mass Transfer, vol. 194, p. 122975, Sep. 2022, doi: 10.1016/j.ijheatmasstransfer.2022.122975.
[10] T. Lacassagne, S. Simoëns, M. E. Hajem, and J.-Y. Champagne, “Ratiometric, single-dye, pH-sensitive inhibited laser-induced fluorescence for the characterization of mixing and mass transfer,” Exp Fluids, vol. 59, no. 1, p. 21, Jan. 2018, doi: 10.1007/s00348-017-2475-y.
[11] T. Lacassagne, S. Simoëns, M. E. Hajem, and J.-Y. Champagne, “POD analysis of oscillating grid turbulence in water and shear thinning polymer solution,” AIChE Journal, vol. 67, no. 1, p. e17044, 2020, doi: 10.1002/aic.17044.
[12] T. Lacassagne, T. Boulafentis, N. Cagney, and S. Balabani, “Modulation of elasto-inertial transitions in Taylor–Couette flow by small particles,” Journal of Fluid Mechanics, vol. 929, Dec. 2021, doi:10.1017/jfm.2021.861.
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[15] T. Lacassagne, “Experimental contributions to the study of hydrodynamics and transfers in complex fluids and flows,” HDR, Université de Lille, Lille, 2025