Lipid extraction from wet microalgal biomass using three different pre-treatment techniques for biodiesel production

Increased supply of fossil fuels has had significant environmental consequences, includinggreenhouse gas emissions and global pollution. Addressing the challenges posed by fossil fuelproduction and usage necessitates the development and adoption of technically advanced,renewable, and cost-effective energy solutions. Biodiesel, derived from various biomassspecies, has gained popularity due to technological advancements in the biofuel field. However,large-scale production and academic studies on microalgae for biodiesel are still in their earlystages, posing significant hurdles in cell disruption, lipid recovery, and biodiesel generationusing existing processing methodologies.This thesis aims to investigate the potential of lipid production in microalgae species,specifically Chlorella vulgaris and Nannochloropsis oculata. The primary focus is onenhancing lipid extraction through different pre-treatment techniques, such as microwave,high-speed homogeniser (HSH), and ultrasonic methods. One of the primary challenges facedin microalgae research is cell disruption, as breaking the algae cells and extracting their lipidsefficiently is crucial. In this study, we adopt a wet method for cell disruption, in contrast tomost recent and traditional studies that focus on using dry algae. To study the adaptability ofthe model, experiments were planned using Design of Experiments (DOE) and analysed usingBox-Behnken designs (BBD). The research outcomes demonstrate that pre-treatmentsignificantly enhances lipid efficiency in both microalgae under specific input conditions.Extracted lipids were subsequently converted into biodiesel through transesterification,employing solvents like methanol, concentrated sulfuric acid, and hexane. Thorough analysisof the biodiesel characteristics was conducted to assess its quality and suitability for large-scaleproduction as a sustainable feedstock. Correlations between Fatty Acid Methyl Ester (FAME)composition and other fuel characteristics were explored to gain valuable insights into thepotential applications of the produced biodiesel. Notably, pre-treatment led to an 14.84%increase in lipid content for Chlorella vulgaris, while Nannochloropsis oculata exhibited amaximum yield of 40.56%. Among the three employed pre-treatment techniques, the highspeedhomogenizer method proved to be the most effective in enhancing lipid extraction fromwet microalgae. This research provides an overview of the investigated work, focusing onenhanced lipid extraction in microalgae and the efficacy of different pre-treatment methods.