In case of heterotrophic cultivation, the culture has a high chance of getting contami­nated especially in open pond cultivations. Apart from this, carbon source is also purchased at a high cost. Photoautotrophic system of algae cultivation is the most frequently used method for biomass growth. It is easy to scale up and can easily take carbon dioxide from the surface air.

13.3 Cultivation Systems

There are two main cultivation systems used for the production of algal biomass:

13.3.1 Open Ponds

The average volumetric yield for this system lies between 0.06 and 0.42 g/L per day. The efficiency of the system depends upon the configuration of the pond and the algal specie that is being cultivated. Open tanks or naturally existing water bod­ies (ponds, lakes, lagoons, etc.) are collectively termed as open ponds and are unproblematic to construct and maneuver. These ponds are kept shallow for the easy penetration of solar radiations. Water and nutrients are continuously circulated in the culture. Output of the pond is measured by calculating the biomass produced each day per unit area. Circular ponds and raceways have an area of about 1 ha whereas extensive ponds can be about 200 ha. Artificial open ponds are further categorized as: