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 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 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.).