Microalgal Harvesting considering Moringa and Watermelon Seeds as Natural Flocculants

Microalgae are aquatic microorganisms that are capable of producing their food through multifarious photosynthetic activities, utilizing carbon dioxide and nutrients as the building blocks to produce biologically complex compounds. Commercially valuable compounds, such as biodiesel, β- carotene and omega-3 fatty acids, are highly sought-after by large energy, agricultural and nutraceutical entities. Harvesting represents approximately 25 to 60% of the total cost of production. Using a natural flocculant reduces energy consumption and makes the algal products, such as omega-3 fatty acids and β- carotene more marketable for feed and animal consumption. Rapid 10.0 mL test tube assessments and batch experiments using Phipps and Bird jar test method were conducted to determine the optimal dosages for the two natural flocculants derived from Moringa oleifera and Citrullus lanatus (watermelon). A reference chemical flocculant (alum) was also used in these experiments. Preliminary results showed that alum and Moringa were more effective than Citrullus lanatus (watermelon). Further experiments need to be conducted considering lower concentrations of watermelon seed powder, as the initial experiments showed concentrations greater than 12.0 g/L resulted in decreasing efficacy.