other algae cultivation systems
Mankind has been using algae for thousands of years. The earliest methods of cultivation involved growing algae in ponds.
Today, other systems are used which speed up the process, produce a higher mass, and make the operation more cost effective.
In contemporary open pond systems, the nutrient solution is slowly stirred around by large paddle wheels. This aims to provide an optimum blend of the solution. This optimum blend, however, is only maintained for a short while after the paddle wheel has passed. A metre of land is required to make use of a metre of surface light - this is the most inefficient of all techniques. Another problem of open systems is the continual contamination with foreign organisms and diseases. Only very robust and fast-growing types of algae can be cultivated in this way.
If a plate system is operated discontinuously, the light surface and protection from contamination are the only advantages over the open pond system.
This system has been predominant during the last twenty years. Energy costs are high and pumps cause considerable stress to the algae. Furthermore, the oxygen released can't escape easily and damages the culture.
Mainly used in laboratories, since a large scale system would be too complex.
A discontinuous system which has solved most of the disadvantages of the other systems. If plate airlift reactors are used in a continuous plant, considerable costs result from the solution being pumped between reactors.
This is a continuous processes but has the disadvantage of high energy costs for pumping and the consequent stress to the algae.
