This thesis investigates the potential of two microalgae strains, Chlamydomonas sp. and Stichococcus deasonii, isolated from samples collected at the Esbjerg harbour in Denmark, as a sustainable feedstock for biofuel production. The study analyses the effects of two different growth medium - fishwater and synthetic saltwater supplemented with plant fertilizer - on the growth and lipid production of these microalgae. The flocculation properties of the microalgae, a critical aspect of biomass separation in microalgae-based biofuel production, are also evaluated.
Laboratory-scale experiments are conducted using 500 mL blue cap flasks continuously aerated with atmospheric air and artificial light from fluorescent lamps. Microalgal growth is assessed using optical density at 600 nm and a hemacytometer, while lipid extraction is carried out with sonication and organic solvents (methanol and chloroform) and analysed using FAME and GC-MS.
Microalgae growth was superior in artificial saltwater medium, averaging 16,678 cells/mL/h, compared to 4,250 cells/mL/h in fishwater. Across all cultures, the dry matter averaged 4% and the lipid content approximately 8%. Dominant fatty acids were identified as C18-3, C18-2, C16, and C18.
The results of this study have implications for industrial-scale production at a local aquaculture company called Alpha-Aqua, where a circular economy model will be employed to convert fishwater that would otherwise go to waste, into biofuel and/or high-value bioproducts including fishfeed. By assesing the growth and lipid production of microalgae strains in different growth medium, and by addressing the challenge of biomass separation through the study of flocculation properties, the thesis aims to contribute to the development of a sustainable and economically viable microalgae-based biofuel industry.