Harvesting of microalgae by centrifugation for biodiesel production: A review

Biodiesel production from algal biomass is widely considered a sustainable alternative to petroleum fuels, especially in the transportation sector. However, the high energy consumption associated with the harvesting phase poses a significant impediment to the substantial commercialization of algal biodiesel. Centrifugation is among those harvesting methods that have a high efficiency close to 100% but can consume more energy than it produces. This review aims to address possible solutions for the issue of the high energy cost of centrifugation as an efficient harvesting technique. In addition, a detailed overview of the potential types of centrifugation that can be used to harvest microalgae with their pros and cons is provided. The most prevalent centrifugal devices that have been identified to be effectively useful to harvest algal biomass include disc-stack centrifuge, solid-bowl centrifuge, hydrocyclone, tubular centrifuge, and multi-chamber centrifuge. Overall, the analysis showed that centrifugation alone is not suitable for the harvesting of microalgae for biodiesel production. Nevertheless, coupling centrifugation with other harvesting technologies, e.g. with flocculation, as a primary pre-concentration step, can increase the energy output significantly thus, reducing the production cost.