Proposal – Scientific Collaboration Italy-Israel 2014

Study and optimization of turbulent mixing processes to enhance microalgae growth for bioethanol production

Scientific Cooperation Italy-Israele, 3rd call

Israel: Tel Aviv University (A.Liberzon),

Italy: Politecnico di Torino (D.Tordella), Università di Catania (M.Gennari).

With respect to plant crop derived bio-fuels, algae are currently considered as the most promising alternative renewable source of biomass for the production of bioethanol. The economical sustainability of the microalgae-biofuel production lies in the «small» details of the production, divided roughly into three types of factors: abiotic (light, temperature, nutrients, oxygen, carbon dioxide, salinity, and toxics), biotic (competition, pathogens) and operational (shear-induced mixing, dilution rate, depth of mixing, harvest frequency, etc.). Our proposal, combining the know-how from the micro-algae, turbulence and mixing processes, seeks to improve the operational factors significantly based on our deep understanding of the key mechanism of the turbulent entrainment across stratification layers: 1) air-water interface with its very strong density jump and 2) culture medium layer, with the Lagrangian dynamics of micro-swimmers in a turbulent environment. The aim of this research is to explore the mixing across stratified layers more in-depth and to try to quantify the vertical mixing in a breeding tank for algae bioethanol production (linking biology to hydrodynamics), in view of a potential application at a larger outdoor scale. We will apply theoretical, numerical, and experimental tools to obtain the parameters for the different combinations of the main parameters: Reynolds and Richardson numbers, as well as provide the quantitative output for the two typical installation sites: open/covered ponds/lakes and closed photo-bioreactors (using classical fluid flow manipulators: pipes ejecting air, grids, etc.).