The effect of pH and time on gravitational sedimentation of microalgae Chlorella sp

Microalgae harvesting is a difficult processing step in the use of microalgae for oil production and other applications. Deployment of an effective and inexpensive harvesting method for achieving microalgae production in large scale is essential for commercialization of this technology. One of the efficient ways is thickening microalgae slurry using gravitational sedimentation prior to applying harvesting method. Here we describe high pH-induced sedimentation of Chlorella sp with the objective of improving the efficiency of microalgae concentration. Basic pH values (9-11.5) of microalgae slurry were tested for different period of gravitational sedimentation (12h-24h). The best removal in dissolved air flotation technique was achieved at pH=10.5 and 24 h of sedimentation time where the chlorella sp culture was concentrated to 3.95 g/L from an initial concentration of 1.01 g/L.