Centrifugation is a standard and efficient process for collection of algal biomass from a dilute solution. It is flexible and can be run continuously to handle huge volumes at scale. The major obstacles to the use of centrifugation in algal biofuel production are high OpEx and CapEx as well as being prone to mechanical problems due to freely moving parts (Bosma et al. 2003). Additionally, high lipid — containing algae are harder to centrifuge and therefore require additional energy to recover by centrifugation.

Generally, it is believed that centrifugation for the primary and secondary dewatering would only be feasible for high-value applications (Molina Grima et al. 2003). However, others feel that a continuous centrifuge would be economical at large-scale Briggs (2004). It is most likely that the use of a centrifuge for secondary concentration with improved and dependable centrifuges could be useful for biofuel production in a continuous and large-scale process.

Hydrocyclones are low-cost continuous centrifuges that have been used for clearing algae and suspended solids from ballast waters. Their efficiency increases with decrease in size of the hydrocyclone and higher flow rates, which could be an issue for industrial scale-up. An example of this issue is a study of solid separation efficiency of 5- and 18-cm-diameter hydrocyclones that delivered 34 and 29 % removal, respectively (Martinez et al. 2007). Recent analyses suggest that the use of hydrocyclones for algal biofuels could be economical (Packer 2009).