Efficiency of the flocculation methods in harvest of Nannochloropsis oculata (Droop) hibberd (Eustigmatophyceae)

Production cost of microalgae is higher compared to the terrestrial plants regarding the production of similar metabolites. One of the reasons why production cost of microalgae is higher is that the processes in harvesting of microalgae which are in micron size and in extraction of the metabolites in vivo are higher in price. Centrifuge separators widely used in harvesting of microalgae cause the production costs to increase due to the high capex and maintenance cost, especially in the separators running in seawater, and the higher energy consumption. It is therefore important to use pre-concentrated culture just before centrifugation to reduce the cost of harvesting process, which is one of the most important reasons increasing the cost of microalgae culture.In this thesis, the efficiency of flocculation, an alternative harvesting method in microalgae, was studied on Nannochloropsis oculata (Droop) Hibberd. It is important to study with Nannochloropsis sp., which has a high growth rate, a usage in almost all marine fish hatcheries and a high fatty acid eicosapentaenoic acid (EPA), since no flocculation methods were studied in detail in this species. Polyelectrolytes, pH, electro-flocculation and ultrasonic-flocculation are the methods used. Consequently, it was seen that pH (10,3) was the most effective one among the methods. In addition, the cream separator used in the experiment was very effective harvesting 85% of the cells without any damage.