Document Type
Theses, Ph.D
Abstract
The transition toward a circular bioeconomy requires sustainable strategies for managing and valorising food industry effluents while reducing reliance on environmentally damaging raw materials such as palm oil, which is associated with deforestation, biodiversity loss and greenhouse gas (GHGs) emissions. Microalgae represent a promising platform for converting nutrient rich industrial by-products into biomass and high-value compounds for food, nutraceutical and bio-based applications. Dairy processing generates large quantities of whey, creating environmental challenges due to its high organic load. Improved whey treatment and valorisation strategies are therefore essential for enhancing sustainability in food production systems. In this study, the biomass productivity of seven microalgal strains (Chlorella vulgaris, Tisochrysis lutea, Dunaliella tertiolecta, Phaeodactylum tricornutum, Nannochloropsis oculata, Tetraselmis chui, and Tetraselmis tetrathele) was evaluated in whey. Among the strains tested, C. vulgaris achieved the highest biomass concentration (6.02 ± 1.22 g/L), while D. tertiolecta, T. chui, and T. tetrathele rapidly assimilated nitrogen compounds. In addition, P. tricornutum and N. oculata reduced phosphate concentrations by nearly 50%, demonstrating effective nutrient remediation. Microalgae were further cultivated in dairy and distillery side streams for lipid production. C. vulgaris produced 4.27 ± 0.31 g/L biomass in whey, whereas T. lutea achieved high lipid yields in distiller’s spent grain (DSG) (308.20 ± 106.49 mg/g dry biomass). Both species synthesised palmitic, stearic, oleic and palmitoleic acids. Additionally, T. lutea produced lauric acid during cultivation in DSG, whereas myristic acid was detected in microalgae grown in whey, highlighting their potential as sustainable alternatives to palm derived lipids. The functional bioactivity of the microalgal extracts was also evaluated. C. vulgaris cultivated in whey exhibited the highest antioxidant activity (36.51%), while T. lutea grown in DSG showed strong angiotensin-converting enzyme (ACE) inhibitory activity (65.16%), comparable to the positive control. These findings demonstrate the potential of agro 2 industrial side streams to support the sustainable production of value-added bioactive therapeutic compounds, without reliance on synthetic production, while contributing to resource recovery and the advancement of a circular bioeconomy.
Finally, ionic liquids (ILs) were investigated as sustainable solvents for the dissolution of cellulose from microalgal cell walls, which constitute a major structural component of the cell wall matrix. Among the ILs evaluated, chloride-based ionic liquids demonstrated the highest efficiency in solubilising cellulose, particularly in aqueous mixtures. These findings highlight their potential for biomass valorisation and resource recovery through more sustainable and efficient bioprocessing strategies.However, further optimisation is required to enhance their industrial applicability and scalability. Overall, this study demonstrates the potential of microalgae to valorise agro-industrial side streams while producing sustainable biomass, alternative lipids and bioactive compounds within a circular bioeconomy framework.
DOI
https://doi.org/10.21427/1t9z-6p84
Recommended Citation
McCarthy, Bozena, "Valorisation Potential of Microalgae as a Sustainable Source of Lipids and Health Promoting Compounds" (2026). Theses. 22.
https://arrow.tudublin.ie/sfehthes/22
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.