Summary of the technology
The main innovation of this invention is:
• This novel photobioreactor combines the mechanism of a bubble column with the air-lift type for higher biomass production than that obtained for both systems separately.
Description of the technology
The research group Polymer processing and pyrolysis of the University of Alicante has developed a novel photobioreactor to grow massively different species of microalgae on industrial scale with automation. The main advantages are: high productivity, better CO2 consumption, better light transfer to the culture, more effective shaking and less cleaning and maintenance time. It can be used in biofuels, aquaculture, food, pharmaceuticals, cosmetics, etc. The research group is looking for companies acquiring this technology for licensing agreement.
For mass cultivation of microalgae can be used different types of photobioreactors. Vertical ones are compact and simple to use them. Currently, there are several vertical reactor configurations: bubble column, air-lift type with suction tube, air-lift type with internal recirculation concentric tubes and submersible reactors. The present invention has been developed to overcome the limitations of the current photobioreactors. In this sense, it has been developed a vertical cylindrical photobioreactor (rigid or flexible), with a flat or a conical bottom, made of transparent material for the optimum light transmission. The photobioreactor can be closed by a transparent lid to prevent foreign substances (dust, insects, etc.) to introduce into it, although the lid does not seal the container, so gases can leave. It also has, at least, one internal recirculation pipe located at the bottom that allows combining the air-lift and bubble column effects. For the optimal microalgae growth, it is necessary to provide light, air and CO2 to control the culture pH and not to reach values that threaten the microalgae survival. The injection of air and CO2 is carried out at the bottom of the photobioreactor. The amount of CO2 injected is controlled by a pH probe with internal temperature compensation. The photobioreactor also has a heat exchanger to maintain the optimum temperature for the microalgae growth. The research group has developed a prototype that is available for experimental demonstration. The photobioreactor has a work volume of 30 litres and its average productivity is 6 g/day. Furthermore, the research group has a pilot plant for carrying out the pre-industrial scaling with reactors of 500 litres (with a production capacity of 100 g/day). There are also available sea water tanks, decantation tanks, filtration, lyophilization and molecular characterization equipment, and culture conditions can be optimized for some microalgae species, such as: Chlorella, Nannochloropsis oculata, Nannochloropsis gaditana, Isochrysis aff. Galbana, Spirulina platensis, Dunaliella salina, Odontella aurita, Phaedactylum tricornutum, Porphyridium cruentum, etc. In this case, the culture conditions have been optimized for Nannochloropsis oculata, a kind of microalgae particularly resistant to pollution (fungi, yeasts, bacteria, viruses, etc.).
Main advantages of its use
- Better control of the culture conditions (pH, temperature, etc.).
- Better light transfer to the culture because the bubbles generated directly mix the culture resulting in an expansion thereof.
- CO2 consumption to reach a suitable microalgae growth is significantly reduced compared with other systems. The best use of this nutrient compared to the conventional air-lift reactor is due to the higher residence time of CO2 it is in the culture: there is a higher concentration dissolved and therefore higher availability for microalgae.
- Due to its configuration, it allows easy scaling on industrial level.
- High productivity.
- Improves nutrient solution: the way in which is injected CO2 to maintain the pH of the culture allows that the residence time of CO2 in the medium increases, thus making better use of it (the whole culture must be crossed to reach the surface).
- It has an automatic pH probe for CO2 injection.
- It is able to be automated (it has aeration, circulation, feeding and harvesting circuits).
- It is robust and easy to install and operate (technical experience is not required for its management).
- It is thermostated for optimum growth of microalgae.
- Maintenance of the uniformity in the distribution of gas in the system.
- The better use of sunlight minimizes energy consumption and cost.
- The stirring is more effective because the effects of both types of reactor (bubble column and air-lift type) are added, which allows a faster microalgae exchange between areas of light and dark.
- There is a lower adhesion of microalgae on the photobioreactor walls, which achieves a greater use of light when the culture reaches high concentrations, and it barely requires cleaning and maintenance.
- Fine chemicals
- Food supplements / vitamins
- Oil and Gas Exploration and Production