Evaluation of flocculation induced by pH increase on harvest efficiency and fatty acids content of microalgae Dunaliella salina, isolated from Lipar lagoon- Chabahar

Today, microalgae are considered as an important source for the production of biofuels and pharmaceutical products. However, the lack of an efficient and economical method for dewatering and harvesting their biomass is is an important challenge to achieve this goal. The important issue for choosing the harvesting method are species characteristics, final product value and energy consumption. Therefore, in this study, the effect of flocculation method with pH change technique (range 6 to 11) using sodium hydroxide and hydrogen chloride on harvesting efficiency, and fatty acid content of Dunaliella salina was tested. The results of this study showed that with the addition of sodium hydroxide and increasing the pH from 8.2 to 9.8, the flocculation process increased upwards from 18 to 90% and then remained constant until: pH 11. In contrast, increasing hydrogen chloride and creating an acidic environment up to: pH equal to 6 had no effect on clot stimulation. The highest coefficient of biomass concentration was observed in alkaline treatment with pH: equivalent to 9.8 which was 10 times the initial concentration (at pH equal to 8.2 the effect of alkaline pH induction technique and the centrifuge technique on the fatty acids content of biomass was tested. In the next stage, the effect of alkaline pH induction technique and the centrifuge technique on the fatty acids content of biomass was tested. The analysis showed that the percentage of lipid and fatty acids of harvested biomass were significantly different from each other. Based on the obtained results, the flocculation method by increasing the pH by 9.8 is a simple and relatively inexpensive technique with high efficiency and is suitable for harvesting Dunaliella salina microalgae for specific purposes.