Lipid Extraction and Cell Disruption Methods for Improving Biodiesel Production by Scenedesmus sp.

Lipid recovery efficiency from microalgal biomass is a critical factor in the commercial viability of biodiesel. Scenedesmus sp. presents a robust cell wall that necessitates the evaluation of specialised disruption techniques to enhance intracellular lipid release and subsequent fuel quality. This study investigated the efficacy of five cell disruption methods—microwaves, ultrasonication, lyophilisation, autoclaving, and electroporation—integrated with three distinct extraction procedures: cold extraction, Soxhlet extraction system, and microwave-assisted extraction. The qualitative and quantitative impacts of these treatments were assessed by analysing the fatty acid methyl ester (FAME) profiles via gas chromatography (GC) following transesterification. The highest total lipid yield (88.97%) was achieved through a combination of microwave disruption and Soxhlet extraction. However, the maximal proportion of methyl esters was obtained when ultrasonication was paired with microwave-assisted extraction (97.64%). Surface analysis using scanning electron microscopy (SEM) of samples subjected to different disruption procedures could support the conclusions. Similarly, when the microalgal biomass was lyophilised beforehand, microwave extraction increased the oleic acid content. These results indicate that the choice of disruption and extraction protocols significantly influences both lipid recovery rate and the proportion of fatty acids in the chemical composition of microalgae. Tailoring these processes is essential for optimising the fatty acid profile for high-quality biodiesel production.