Construction, operations and maintenance
Large Scale: If produced industrially: In green houses, large water tanks (raceway ponds), water, fertilizer, pump/ paddle wheel to move it.
Small scale: Materials:
- Flask of live spirulina
- tank – see manufacturing
- An electric mini-pump – 220V, 5-7W
- 1000L of culture medium (fertilizer and mineral salts dissolved in drinking water)
- Measuring tools – thermometer, Secchi disk, litmus paper, etc
- Harvesting equipment
- Extruder, dryer
- Air compressor, such as aquarium ones.
A concentrated spirulina culture is then used to seed the pond containing culture medium. This can be obtained from culture floating on an existing pond, or recently harvested. This is mixed into the culture medium and allowed to grow. It should be regularly agitated using an electric pump or by stirring manually. The temperature, pH and concentration of algae should be monitored. Once the concentration increases to about 0.5g/L (use a Secchi disk to measure) it must be harvested. This can be done by simply filtering it through a cloth to obtain a “biomass” of about 10% dry matter per litre. The biomass obtained is then pressed in a cloth to produce a kind of cake. The culture medium can then be reused, by adding any of the ingredients which were used up by the Spirulina.
Spirulina is most nutritious in its wet form. However this lasts at most for a few days if refrigerated, and only a few hours at room temperature. Hence if it needs to be transported or stored it must be dried. If dried and packaged well it can be stored for at least a year without losing nutritional value. However if dried it acquires an unpleasant smell and taste, and is inconvenient to use. It can then also be combined with various other food products or simply packaged on its own.
The production of Spirulina requires manufacturing of a tank. The size of this depends on the scale of production, and the number of tanks. 1 tank of 18m2 produces approximately 150g of Spirulina per day.
Materials:
- 2 polyethylene sheets 2mm thick.
- 4 frames
- 3 bars (metal/bamboo, etc.)
- Bricks, breeze blocks, packed earth, or planks for walls
Build up the walls, approximately 30cm high with packed earth, bricks or planks. The material to be used depends on the weather conditions, and presence of rodents, termites etc. Cover the sides and the bottom with one polyethylene sheet. Create a temporary compartment (200L) to produce Spirulina needed to seed the whole tank. Reinforce the walls with metal/bamboo frames and cover with a second plastic sheet.
Maintenance
The culture medium and tanks need to be protected from contamination by foreign algae, insects and toxicity. Also the level of the pond and amount of nutrients needs to be maintained by regularly replacing the fertilizers and water. Further the temperature and pH need to be maintained. Details on how this is done can be found in the manual. It is useful to replace a small amount of the solution with a completely fresh amount, to prevent deterioration of the culture medium.
Further, tanks usually need to be replaced or repaired after 3-4 years. Other equipment may also have to be replaced.
Costs
An estimate for the total costs however is 5-7 euros per kg of spirulina. The main costs involved in the local production of Spirulina are labour, nutrients, packaging, capital and administration. The costs of course depend on the local availability of materials.
In india for example, the cost of building a tank of 18m2 is 166 euro and a feeding programme here produces Spirulina at a cost of 0.01euro per child per day.
Field Experiences
Spirulina programs are currently being implemented in Burkina Faso, Cameroon, Central African Republic, Democratic Republic of Congo, Guinea Conakry, Kenya, Madagascar, Mali, Niger, India, and Vietnam.
One example of a successful business initiative revolving around Spirulina production can be seen in Madurai, India. Here 15 women run a production facility of 40 Spirulina tanks. They work to produce 150kg of Spirulina per month.
They pack the Spirulina in dry form of 2 gram sachets and sold to two local NGOs. The Spirulina is also combined with millet, jaggery, and sesame to produce “chikki” a type of energy bar to feed 2000 children per day from slums in the neighborhood. At this scale of production, the facility is extremely efficient, and produces at a cost of 0.01 euro per child per day. They currently do not sell in the open market, as this requires more management and marketing skills, however this is being worked on