Algae Harvesting - Definition, Glossary, Details - OilgaeRefers to the act or process of gathering the algae that has been cultivated and grown. Because of the nature of algae and the diverse habitats that it grows in, algae harvesting might need some special techniques to be employed in specific cases.Algae can be harvested using microscreens, by centrifugation, by flocculation and by froth flotation.Alum and ferric chloride are chemical flocculants used to harvest algae. A commercial product called "Chitosan", commonly used for water purification, can also be used as a flocculant but is far more expensive. The shells of crustaceans are ground into powder and processed to acquire chitin, a polysaccharide found in the shells, from which chitosan is derived via de-acetylation. Water that is more brackish, or saline requires additional chemical flocculant to induce flocculation. Harvesting by chemical flocculation is a method that is often too expensive for large operations. Interrupting the carbon dioxide supply to an algal system can cause algae to flocculate on its own, which is called "autoflocculation".In froth flotation, the water and algae are aerated into a froth, with the algae then removed from the water.Ultrasound based methods of algae harvesting are currently under development, and other, additional methods are currently being developed.