Today, microalgae play an important role in our daily life from food to biofuel. But how are they cultivated? What are the necessary tools to produce algae biomass?
The production of microalgae is getting easier. Innovating systems are now available for the general public. Today, it is possible to obtain fresh spirulina at home almost as easily as you squeeze orange juice in the morning. But what are the production systems for research centers, laboratories or industrial companies?
The algae cultivating systems are divided in two categories: closed systems and open systems
A closed system will have the advantage to protect microalgae of any exterior threat (bacterium, contaminations…). Moreover, it allows a better control of the environment thanks to the adjustment of the different parameters via a pilot system.
On the other hand, open systems also have their advantages. They have usually a less expensive purchase price and quicker to learn how to handle.
Your microalgae production system will depend on the type of microalgae cultivated as well as the market you wish to address. For example, the cultivation of Isochrysis galbana affinis Tahiti is very hard in an open system but is very efficient in a closed one. The cultivation of spirulina can be in an open system as well as a closed one. However, it is preferable to cultivate in a closed system if you wish to sell fresh biomass for food. It is preferable for security and hygienic reasons.
The different closed microalgae production systems
This list is non-exhaustive
Photobioreactors
They are autotrophic closed microalgae cultivation systems where cultivation parameters are controlled (agitation, temperature, medium, pH…) to allow the microalgae to carry out their photosynthetic process. More expensive purchase price than other production systems, they however avoid contamination risks and allow a production all year long.
• Flat panel photobioreactor
This cultivation tool obtains microalgae with a very high concentration thanks to the homogeneous exposure to light. Therefore, this cultivation system obtains high productivities. However, it is very complicated to clean the biofilm is very quickly created due to the poor hydrodynamic in this production system.
• Tubular horizontal photobioreactor
It is less expensive at the purchase but also less efficient in terms of productivity. They obtain poorer performances and the operation costs are higher because they are very energy-consuming. One of the major differences between vertical photobioreactors and horizontal photobioreactors is their compatibility with microalgae. All microalgae can’t be cultivated in horizontal systems. Also, biofilm appears quicker in this system.
• Tubular vertical photobioreactor
These microalgae systems are more expensive at the time of the purchase but more affordable in the long term. This system has higher concentrations and a bigger productivity thanks to a smooth and controlled agitation that avoid the emergence of biofilm. Another advantage for the culture with this photobioreactor is the compatibility with most microalgae. As you must probably guessed, this is our favorite system at Synoxis Algae.
Plastic bags
It is the cheapest microalgae cultivation system to purchase. It is quick to put in place and easy to operate. This method consists in hanging a plastic bag with a CO2 supply pipe. Very affordable, it is however the system with the shortest lifespan. Therefore, it becomes very expensive in the long term. Indeed, the bags are then thrown away and new ones are used as a replacement. Moreover, the biofilm is created very quickly with this method. If you wish to have an ecologic system, this system is not adapted for your needs.
The different opened microalgae production systems
Aquaculture tanks with important diameters (50-70 cm)
This cultivation method is relatively reasonable to purchase. Microalgae are cultivated in transparent plastic tank (PMMA, PETG, PVC) and a bubbling is created for the agitation. However, this cultivation system is very expensive in operation cost. Moreover, the culture has very little stability, low productivity and poor microalgae quality.
Raceway ponds
These production systems are the most commonly used in microalgae cultivation. They are open pounds in the shape of a racetrack. They are generally used by those who wish to produce strong microalgae in large quantity at low cost. However, they have important risks of contaminations and their concentrations are relatively low. Plus, with those systems, productivity is linked to seasonality.
Making the right choice for your microalgae cultivation system
The goal for the buyer of a production microalgae cultivation system is to weigh the pros and cons by taking into account different criteria and prioritizing them according to their needs: initial investment, operation cost, productivity, concentration, preservation of the culture, ease of use, compatibility with the strains, the microalgae cultivated…
Caution: it is necessary to take into account the Capex-Opex for the purchase of your production system… Some systems are more expensive when you buy them but are profitable with time. Taking the time to consider all option is essential for your choice.
We designed several photobioreactors meeting the different needs of our clients and easy to operate, click here to contact us.
