Algae culture

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Algae culture is a form of aquaculture used to grow algae . This usually involves the cultivation of microalgae or phytoplankton . The products of the algae cultures are raw materials for the production of algae fuel , biodiesel , fertilizers and pharmaceuticals. The raw material yield per area is significantly higher than with other crops such as the oil palm , which are considered high-yielding .

Algae selection

The breeding takes place mostly as a monoculture . Pure cultures are z. B. obtained with the method of serial dilution. A mixed sample is diluted several times in a row until it statistically only accommodates one single species. The samples are then analyzed microscopically. The desired species is cultivated and then analyzed again in order to create larger cultures.

rearing

Light, water, carbon dioxide and minerals are essential factors in rearing. The basic reaction is the build-up of carbohydrates and the release of oxygen ( photosynthesis ). Depending on the species, the temperature must be kept in the range that enables high productivity. With open-basin cultivation, the culture is only supplied with light from above. As the algae grow, the algae in the upper layers block growth in the lower layers through absorption . In order to use larger tanks and thus increase the yield, the culture medium is stirred or circulated so that the algae grow evenly. The movement can also be achieved by blowing air into deeper layers. Stirring also prevents the algae in the upper layers from being exposed to direct sunlight. Blowing in air also prevents anaerobic conditions that can lead to odor nuisance from the decomposition products of dead algae.

Photobioreactors

Algae can be cultivated in open basins or channels or in photobioreactors . The latter have proven their worth for the extraction of raw materials for biodiesel production. One disadvantage of open pools is contamination by other microorganisms. Closed systems are used for monocultures.

Algae harvest

Typical harvesting methods such as filtration , centrifugation , flocculation or flotation separate the algae from the cultivation medium. By interrupting the supply of carbon dioxide, some species flocculate on their own.

Oil extraction

First the algae are mechanically crushed and then dried. Then the oil is pressed out. Also extraction methods , for example with n -hexane as the extraction agent, can be used. The extraction process can be greatly accelerated using ultrasound .

Individual evidence

  1. ↑ Cyanobacteria are also processed using the same method. Compact lexicon of biology - algae culture . www.wissenschaft-online.de. Retrieved October 31, 2009.

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