Centrifugation involves the application of centripetal acceleration to separate the microalgae from the culture medium (Harun et al., 2010) and is perhaps the fastest cell-recovery method based on density gradient. The centrifuge disks are easy to clean and sterilize, and centrifugation can be applied to any kind of microalga (Christenson and Sims, 2011).

Heasman et al. (2000) reported that 88-100% of centrifuged cells were viable and the col­lection efficiency was 95-100% at 13,000xg. However, the centrifuge has some disadvantages: The cells are exposed to a high gravitational force, which can alter the cell structure; the re­covery of fragile microalgae biomass requires low-speed centrifugation; the salt contained in the microalgal culture medium can cause rapid corrosion of equipment; and large-scale processes require costly equipment, such as continuous centrifuges (Pires et al., 2012).