From culture, harvest to pretreatment of microalgae and its high-value utilization

Microalgae can be used to produce promising third-generation biomass fuel, the combustion of which produces carbon-neutral CO2. However, economic sustainability has become a major obstacle limiting its development. Hence, it is necessary to optimize the upstream and downstream processes of microalgae processing techniques and find high-value utilization of microalgae biomass. In this work, a comprehensive overview of microalgae culture parameters is provided. It systematically summarizes different harvesting methods, sorting out their strengths and dilemmas for various types of microalgae and application scenarios. Microalgae pretreatment, including drying and lipid extraction, is the most energy-consuming step in microalgae utilization. This work also explains the pros and cons of advanced techniques in lipid extraction, such as supercritical fluid extraction, ultrasonic assisted extraction and microwave assisted extraction. In addition to traditional bioenergy applications, this present work analyzes currently feasible high-value utilization of microalgae. As promising sustainable biomass, the combination of high-value utilization of microalgae and environmental governance can expand the application scenarios of microalgae utilization. Finally, the strengths and weaknesses of each segment of microalgae pretreatment and utilization are compared. This information is valuable for guiding the high-value utilization of microalgae.