Microalgae Harvest Technology

In the past few decades, microalgae have been studied extensively due to its various benefits. These oil-amassing species have the potential for large-scale biofuel production and other value-added products. The biodiesel production from microalgae does not compete with agricultural land or food availability. However, harvesting the microalgal cells from its culture medium is a huge bottleneck for its widespread commercialization. Harvesting of microalgae includes separation of the microalgal solid cells from the dilute algal suspension of 0.02–0.05% dry solids concentration. Due to the dilute nature of culture medium, the solid-liquid phase separation is expensive and energy intensive. This separation accounts for almost 20–30% of the total capital required for the project, thus, microalgae derived biofuel is not cost-effective. This chapter highlights few of the harvesting methods currently employed in the industry and lists down respective advantages and disadvantages. Harvesting of microalgae is a two-step, sometimes three-step, process. The first step is to thicken the dilute suspension to concentrate it to 2–5% solids concentration. Then, this slurry is dewatered to obtain the desired 15–25% dry biomass concentration for further extraction to biodiesel or animal feed. The selection of suitable harvesting method depends on the properties and characteristics of the microalgae and the target product. This chapter also emphasizes the importance of continued research and innovation in the microalgal study for a sustainable future.