Chapter 9 - Microalgal Cell Disruption and Lipid Extraction Techniques for Potential Biofuel Production

Abstract

Microalgal biofuels are considered as one of the most promising substitutes to the nonrenewable fossil fuels. However, the efficient recovery of microalgal lipids is emergent for the overall process economics and sustainability. The conventional lipid extraction technique entails direct use of organic solvents to liberate the intracellular lipids, thus making the extraction process more time-consuming and less eco-friendly. Furthermore, the efficiency of extraction process is affected by several problems, such as the rigid structure and composition of microalgal cell walls, the water content of biomass, the limited accessibility of lipids, the reduced mass transfer, and the formation of stable emulsions. Various modifications (e.g., use of green solvents, direct transesterification, pretreatment for disrupting microalgal cells, etc.) to conventional lipid extraction have been proposed to mitigate the problems associated with lipid extraction. Among them, the pretreatment approach (i.e., mechanical, chemical, biological cell disruption) in combination with solvent-based extraction would be a promising approach to address the problems during lipid extraction. Therefore, intensive research, review, and analysis are required to understand the challenges in lipid extraction and to develop a useful extraction process in terms of biomass status (dry/wet), solvent use, lipid yield, extraction time, and scalability. In this chapter, we have reviewed the composition and possible applications of microalgal lipids with the main challenges in their extraction process. Furthermore, the advantages and limitations of several pretreatment methods for cell disruption have been comprehensively discussed.