page_title: Algaculture
section_title: Harvesting
hierarchical_section_title: Algaculture / Growing, harvesting, and processing algae / Harvesting
caption_attribution_description: English: Edible seaweed farming on the small island of Nusa Lembongan, southeast of Bali, in Indonesia. The seaweed is growing on a rope. The bay on the coast is marked out by wooden posts into rectangular plots that are owned by different families. A boat is seen in some of the plots.
context_page_description: Algaculture is a form of aquaculture involving the farming of species of algae.
  The majority of algae that are intentionally cultivated fall into the category of microalgae. Macroalgae, commonly known as seaweed, also have many commercial and industrial uses, but due to their size and the specific requirements of the environment in which they need to grow, they do not lend themselves as readily to cultivation.
  Commercial and industrial algae cultivation has numerous uses, including production of food ingredients such as omega-3 fatty acids or natural food colorants and dyes, food, fertilizer, bioplastics, chemical feedstock, pharmaceuticals, and algal fuel, and can also be used as a means of pollution control.
  Global production of farmed aquatic plants, overwhelmingly dominated by seaweeds, grew in output volume from 13.5 million tonnes in 1995 to just over 30 million tonnes in 2016.
context_section_description: Algae can be harvested using microscreens, by centrifugation, by flocculation and by froth flotation.
  Interrupting the carbon dioxide supply can cause algae to flocculate on its own, which is called "autoflocculation".
  "Chitosan", a commercial flocculant, more commonly used for water purification, is far more expensive. The powdered shells of crustaceans are 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 larger amounts of flocculant. Flocculation is often too expensive for large operations.
  Alum and ferric chloride are other chemical flocculants.
  In froth flotation, the cultivator aerates the water into a froth, and then skims the algae from the top.
  Ultrasound and other harvesting methods are currently under development.
caption: A seaweed farmer in Nusa Lembongan gathers edible seaweed that has grown on a rope.
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