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Ecodesign process for microalgae fractionation : use of supercritical CO2, membrane technology and low frequency ultrasounds

Obeid, Sara. Ecodesign process for microalgae fractionation : use of supercritical CO2, membrane technology and low frequency ultrasounds. PhD, Sciences des Agroressources, Institut National Polytechnique de Toulouse, 2018

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Abstract

The development of an integrated and simplified biorefinery process able to produce a wide range of multiple molecules of interest is crucial for the commercialization of microalgae. The objective of this study was to simplify the downstream processes of microalgae valorization by optimizing the selectivity of extraction while respecting the principles of ecodesign. On the one hand, using dry microalgae, supercritical CO2 extraction was carried out for selective recovery of neutral lipids without cell disruption pretreatment. Results showed that up to 97% of neutral lipids from Chlorella vulgaris were extracted. Neutral lipids from Nannochloropsis oculata represented most of the extracts (83%), whereas the proportion of glycolipids and phospholipids did not exceed 12.1% and 5.3%, respectively. Following the lipophilic recovery via supercritical extraction, 67 % of total proteins were released using double stage aqueous extraction. Moreover, up to 84% of the extracted proteins free from pigments were obtained using semi-frontal ultrafiltration. On the other hand, a green ultrasound assisted extraction process using water as solvent was performed on wet microalgae for protein recovery at low frequency (12 kHz). Results of Chlorella vulgaris showed that almost all the protein content (97%) was released in the aqueous medium allowing a highly selective extraction while microalgae cells remained intact. In contrary, total protein content were co-extracted with impurities from totally disintegrated Spirulina sp. Thus, for protein clarification, quasi-frontal ultrafiltration process was carried out leading to 67% of total proteins obtained in the permeate. Furthermore, up to 95% of phycocyanine were retained with other impurities like residues and pigments. Since selective extraction of all the molecules of interest in microalgae biomass remains a challenge, additional research must be conducted to alleviate the downstreamprocess.

Item Type:PhD Thesis
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Institution:Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
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Research Director:
Pontalier, Pierre-Yves and Ismail, Ali
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Deposited On:06 Nov 2019 09:15

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