Gifuni, Imma (2017) Valorisation of starch production in microalgae biorefinery. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Lingua: English
Title: Valorisation of starch production in microalgae biorefinery
Date: 28 December 2017
Number of Pages: 152
Institution: Università degli Studi di Napoli Federico II
Department: dep19
Dottorato: phd012
Ciclo di dottorato: 30
Coordinatore del Corso di dottorato:
Marzocchella, AntonioUNSPECIFIED
Date: 28 December 2017
Number of Pages: 152
Uncontrolled Keywords: microalgae, starch, biorefinery, intensive production, downstream
Settori scientifico-disciplinari del MIUR: Area 09 - Ingegneria industriale e dell'informazione > ING-IND/25 - Impianti chimici
Date Deposited: 15 Jan 2018 10:10
Last Modified: 14 Mar 2019 12:15


The present research project was aimed at the valorisation of microalgal starch production within a biorefinery approach. The activity was carried out at the Dipartimento di Ingegneria Chimica, dei Materiale e della Produzione Industriale and at the Dipartimento di Biologia of the Università degli Studi di Napoli ‘Federico II’. Some tasks were carried out at the Laboratoire de Génie des Procédés environnement agro-alimentaire of the University of Nantes (France). The activity has been organized in four main paths: T1) Selection of a robust microalgal strain for starch production. This task was aimed to select a robust microalgal strain for industrial production of the biomass for biorefinery applications. The selection was based on the biomass and starch productivity. Two fresh water microalgae, Chlorella sorokiniana and Scenedesmus vacuolatus, and two seawater microalgae, Dunaliella tertiolecta and Tetraselmis chuii were investigated. C. sorokiniana was selected as the best starch producer. The effect of nitrogen and CO2 concentration on the biomass and starch productivity was investigated. At light irradiance of 300 μmol m-2s-1, the optimal concentration of nitrogen and CO2 were 32 mg L-1 and 2%, respevtively. A complete biochemical characterization of the microalgal biomass was carried out as a function of the growth time. The onset of nitrogen depletion was identified as the suitable condition for the simultaneous recovery of multiple products: starch, proteins, lipids (34, 37, 21 %DW, respectively). T2) Characterization of the microalgal starch granules. The goal of this task was to prove that the microalgal starch granules have interesting physic and chemical properties required for industrial applications. Limited information was available in literature about microalgal starch, then additional analysis were necessary to validate the potential applications of this starch type. C. sorokiniana starch extraction was optimized and a preliminary physic-chemical characterization was carried out. The results pointed out many similarities with cereals starch. However, the reduced size of the starch granules from microalgae addressed specific and high-value applications as emulsifier, molecules carrier, functionalization, bioplastics. T3) Intensification of microalgal biomass production. The increase in the microalgal biomass concentration and productivity are crucial issues for the process optimization. A new ultra-thin flat photobioreactor was designed and built. The performances were assessed for C. sorokiniana. The effect of the light intensity on the growth and the biochemical composition of C. sorokiniana was also investigated. Biomass concentration of 10 g L-1 was established in less than 100 hours at medium light irradiance of 300 μmol m-2 s-1. T4) Mild downstream processes for the recovery of starch and other components. The goal was the exploitation of several microalgal components. The simultaneous recovery of starch and antioxidants was carried out in cooperation with Dr. Ganna Petruk, Biotechnology PhD student. The recovery of starch and proteins from microalgae was carried out at Laboratoire de Génie des Procédés environnement agro-alimentaire, Nantes University. The effect of bead milling cell disruption on products recovery was investigated. A model to describe the disruption process was successfully applied to the product recovery. Integration of microalagal mechanical disruption, centrifugation and membrane separation for the simultaneous recovery of starch and proteins from microalgal biomass was investigated.


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