Microalgae cultivation in view of resource and energy recovery

• Autores: Sergi Carbonell Chacón
• Directores de la Tesis: Juan Antonio Baeza Labat (dir. tes.), Albert Guisasola Canudas (codir. tes.)
• Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2019
• Idioma: español
• Tribunal Calificador de la Tesis: Ivet Ferrer Marti (presid.), Paqui Blánquez Cano (secret.), Sergio Ponsá Salas (voc.)
• Enlaces
  • Tesis en acceso abierto en: TESEO
• Resumen

  • The objective of this doctoral thesis is to enhance the production of microalgae with the aim to obtain organic products of high added value and energy. The elaboration of this thesis is part of two European projects, Mar3 and Oli-PHA, which had as their objective the bio-remediation of oil spills through the use of gelling agents and production of PHA for use in packaging in the food industry, respectively.

    Chapter 4 of the doctoral thesis focuses on the parameters affecting the design of a photobioreactor (FBR). The intensity of light, its quality, the depth of the reactor or the light/dark cycles applied during the culture of the microalgae significantly affect their metabolism. The culture strategy, whether photoautotrophic, heterotrophic or mixotrophic also plays an important role in the design of a FBR. The hydrodynamics of the reactor, the optimal way to homogenize the liquid during culture and the transfer of mass and energy are also investigated in this memory chapter. An extensive bibliographic research allows reaching a suitable design criterion for the design of an efficient FBR for the Chlorella vulgaris culture.

    Chapter 5 of the memory develops a kinetic model with the aim of describing the behaviour of cyanobacteria Synechocystis sp. PCC 6803 during its cultivation for the production of PHA. The proposed kinetic model based on nutrient speciation and pH correctly describes the experimental results obtained during the experimental phase of the research and determines the different semi-saturation constants for the different nutrients used in the growth of the microorganism. It is confirmed both experimentally and theoretically that the growth of cyanobacteria is significantly influenced by the concentration of initial phosphorus in the medium. Finally, the proposed model is exploited with simulations changing the light/dark cycle in order to determine the behaviour of the system as a function of these conditions.

    Chapter 6 focuses on obtaining energy from the surplus biomass of the cyanobacteria Synechocystis sp. PCC 6803 used for the production of PHA. For the first time the production of biogas from this cyanobacterium is reported and the results obtained are similar to those found in the bibliography in previous studies using microalgal biomass. Thermal pre-treatments and co-digestion with another substrate, wastewater from the olive oil production process in this case, are used in order to determine the increase in biogas production thanks to the application of these treatments. Finally, the kinetic constants of the process are determined using the Gompertz equation.