Separation processes in microalgae biorefining

Identifier:  TDX:2535

Handle: https://hdl.handle.net/20.500.11797/TDX2535

Authors:  Nurra, Claudia

Abstract:
This thesis focuses on the development of new approaches for separation processes in biodiesel production from microalgae by membrane technology. Biodiesel production from microalgae is a theme being developed in the last years that still need more investigation in order to reduce its costs. Among all steps involved in the process this thesis focuses the investigation of the microalgae dewatering by using several membrane filtration techniques and on transesterification by using a catalytic membrane reactor. Harvesting step is one of the major responsible of the final cost of microalgae biodiesel, and transesterification reaction needs the utilisation of too much quantity of water and many stages that make it unfeasible for this application. Enhancements are needed in this sense, starting from the research of cheaper methods and materials for the first process to simpler configurations for the latter one. Considerable attention has been dedicated to the complete understanding of membrane filtration technology in this application from the laboratory to the pilot plant scale. To reach these goals specific studies have been performed for this application on: (i) new materials in membrane filtration, from polymers already known (PSf, PAN) to polymers usually not employed in membrane industry (ABS, PETg, sawdust CA); (ii) new technologies in microalgae dewatering, as vibrating cross-flow filtration system; (iii) new perspectives in the transesterification reaction, with the utilization of heterogeneous catalyst immobilized on a membrane. Finally, permeability is the most studied parameter in membrane filtration technology for the evaluation of fouling phenomena. This parameter depends from many variables and its study is particularly important when synthesized membranes with unknown characteristics are used. To simplify its attainment a final theoretical study has been carried out on membrane permeability prediction by the development of a model conceived for porous membranes.