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Title:
PLANT FOR THE CULTIVATION OF ALGAE, PREFERABLY MICROALGAE
Document Type and Number:
WIPO Patent Application WO/2019/244178
Kind Code:
A1
Abstract:
Plant (10) for growing algae, preferably microalgae, comprising a first processing unit (1 1) provided with culture means (14) configured to grow a biomass of algae, a second processing unit (12) configured to concentrate said biomass of algae, and a third processing unit (13) configured to cause, in the concentrated biomass of algae, under certain stress conditions, the transformation and accumulation of molecules of economic interest.

Inventors:
MARON NICOLA (IT)
MOROSINOTTO TOMAS (IT)
SIMIONATO DIANA (IT)
Application Number:
PCT/IT2018/050235
Publication Date:
December 26, 2019
Filing Date:
November 28, 2018
Export Citation:
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Assignee:
TMCI PADOVAN S P A (IT)
International Classes:
C12M1/00; C12M1/26; C12M1/34; C12M1/42
Foreign References:
US20050214897A12005-09-29
EP1681060A12006-07-19
Other References:
DATABASE WPI Week 201036, Derwent World Patents Index; AN 2010-E79234, XP002788965
PELAH D ET AL: "THE EFFECT OF SALT STRESS ON THE PRODUCTION OF CANTHAXANTHIN AND ASTAXANTHIN BY CHLORELLA ZOFINGIENSIS GROWN UNDER LIMITED LIGHT INTENSITY", WORLD JOURNAL OF MICROBIOLOGY AND BIOTECHNOLOGY, KLUWER ACADEMIC PUBLISHERS, DO, vol. 20, 1 January 2004 (2004-01-01), pages 483 - 486, XP001091174, ISSN: 1573-0972, DOI: 10.1023/B:WIBI.0000040398.93103.21
Attorney, Agent or Firm:
PETRAZ, Davide Luigi et al. (IT)
Download PDF:
Claims:
CLAIMS

1. Plant (10) for growing algae, preferably microalgae, comprising a first processing unit (1 1) provided with culture means (14) configured to grow a biomass of algae, characterized in that it also comprises a second processing unit (12) configured to concentrate said biomass of algae, and a third processing unit (13) configured to cause, in the concentrated biomass of algae, under certain stress conditions, the transformation and accumulation of molecules of economic interest.

2. Plant (10) as in claim 1, characterized in that said first processing unit (11) comprises one or more suitable first photobioreactors (14), which are configured to be selectively exposed directly to natural light, and/or to artificial light.

3. Plant (10) as in claim 2, characterized in that each of said first photobioreactors (14) is connected to a source of C02 or other carbon source and in that said CO2 is optionally suitable to be insufflated together with air into each of said photobioreactors (14), wherein the percentage of said CO2 in said air is preferably comprised between about 0.1% and about 25%, even more preferably in a percentage of 5%.

4. Plant (10) as in claim 2 or 3, characterized in that the initial concentration of said biomass of algae in each of said first photobioreactors (14) is preferably comprised between about 0.2 g/1 and about 0.4 g/1, and preferably at a temperature of 22 ± 2 °C when using Chlorella zofmgiensis, and in that the concentration of biomass and higher or lower temperatures can be used depending on the species.

5. Plant (10) as in claim 2, 3 or 4, characterized in that in each of said first photobioreactors (14) the culture of said biomass of algae is preferably maintained in a growth defined as“semi-continuous”, since it is provided that said algae are collected when their concentration reaches a predefined value, preferably comprised between about 0.7 g/1 and about 1.5 g/1.

6. Plant (10) as in any claim hereinbefore, wherein said alga is the microalga Chlorella zofmgiensis, characterized in that in each of said first photobioreactors (14) a growth medium is used having the following reagents, in the corresponding concentrations, expressed in grams per liter:

7. Plant (10) as in claim 6, characterized in that the concentration of said reagent NaNO3 is preferably comprised between about 0.2 g/1 and about 1.5 g/1, and even more preferably it is about 0.375 g/1.

8. Plant (10) as in any claim hereinbefore, characterized in that said second processing unit (12) comprises a compaction apparatus (16) configured to concentrate said biomass of algae exiting from said first processing unit (11) to take it to a much higher concentration, preferably between 5 g/1 and 300 g/1.

9. Plant (10) as in any claim hereinbefore, characterized in that said third processing unit (13) comprises one or more second photobioreactors (18) each configured to receive said concentrated biomass of algae exiting from said second processing unit (12), and in that in each of said second photobioreactors (18) the conditions are optimized to have an imbalance between the availability of energy for the cells, such as light, and the inability to produce biomass, because the cells are limited in the availability of carbon dioxide and mineral nutrients, therefore said algae are able to increase the synthesis of molecules of economic interest.

10. Plant (10) as in claim 9, characterized in that in each of said second photobioreactors (18) it is provided to combine several stimuli at the same time, including the addition of salt, such as NaCl, and glucose, which allows both to increase the yield of the molecules of economic interest, and also to reduce the time needed for stimulation.

11. Plant (10) as in claim 9 or 10, characterized in that in each of said second photobioreactors (18) said concentrated biomass of algae is exposed to a moderate light intensity, preferably comprised between about 20 pmoles and about 200 pmoles of rrfV photons, removing the CO2.

Description:
“PLANT FOR THE CULTIVATION OF ALGAE, PREFERABLY MICROALGAE”

FIELD OF THE INVENTION

The present invention concerns a plant for the cultivation of algae, preferably microalgae, for example, but not only, the Chlorella zofmgiensis microalgae, for the production of molecules of economic interest such as for example carotenoids, omega 3, lipids and carbohydrates, using photobioreactors selectively exposed to natural or artificial light.

BACKGROUND OF THE INVENTION

The properties of algae and in particular of microalgae are known, which, since they are able to perform photosynthesis, are important for life on Earth. In fact they produce about half of the atmospheric oxygen and simultaneously use the carbon dioxide of greenhouse gases to grow photo-autotrophically.

It is also known that it is possible to accumulate to a large extent the desired products in algae/microalgae by modifying environmental factors, such as for example temperature, lighting, pH, the CO 2 supply, salts and nutrient substances.

It is also known that for the optimal growth of algae/microalgae the sizes and geometry of the container, or photobioreactor, in which they are grown, as well as the exposure to light/irradiation and the concentration of cells inside the photobioreactor are all important.

However, known plants for the cultivation of algae are rather complex and not very economical.

One purpose of the present invention is to provide a plant for the cultivation of algae, preferably microalgae, which is simple, reliable and economical, both in construction costs and in maintenance costs.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claim, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea. In accordance with the above purpose, a plant according to the present invention for growing algae, preferably microalgae, comprises a first processing unit provided with culture means configured to grow a biomass of algae.

In accordance with one characteristic of the present invention, the plant also comprises a second processing unit configured to concentrate the biomass of algae, and a third processing unit configured to cause, in the concentrated biomass of algae, under certain stress conditions, the transformation and accumulation of molecules of economic interest.

In accordance with another characteristic of the present invention, the first processing unit comprises one or more suitable first photobioreactors, which are configured to be selectively exposed directly to natural light, and/or to artificial light.

In accordance with another characteristic of the present invention, each of the first photobioreactors is connected to a source of CO 2 or other carbon source and the CO 2 is suitable to be preferably insufflated together with air into each of the photobioreactors; moreover the percentage of the CO 2 in the air is preferably comprised between about 0.1% and about 25%, even more preferably in a percentage of 5%.

In accordance with another characteristic of the present invention, the initial concentration of the biomass of algae in each of the first photobioreactors is preferably comprised between about 0.2 g/1 and about 0.4 g/1. The concentration values of the biomass can vary according to the species used for growth. Preferably the temperature used is 22 ± 2°C, but a wider range can be tolerated (e.g. 15-30°C) even for other species.

In accordance with another characteristic of the present invention, in each of the first photobioreactors the culture of the biomass of algae is preferably maintained in a growth defined as“semi-continuous”, since it is provided that the algae are collected when their concentration reaches a predefined value, preferably comprised between about 0.7 g/1 and about 1.5 g/1.

In accordance with another characteristic of the present invention, the second processing unit comprises a compaction apparatus configured to concentrate the biomass of algae exiting from the first processing unit to take it to a much higher concentration, preferably between 5 g/1 and 300 g/1. In accordance with another characteristic of the present invention the third processing unit comprises one or more second photobioreactors, each configured to receive the concentrated biomass of algae exiting from the second processing unit, and, moreover, in each of the second photobioreactors the conditions are optimized to have an imbalance between the availability of energy for the cells, such as light, and the inability to produce biomass, because the cells are limited in the availability of carbon dioxide or other sources of carbon and mineral nutrients, therefore the algae are able to increase the synthesis of molecules of economic interest.

In accordance with another characteristic of the present invention, in each of the second photobioreactors it is provided to combine several stimuli at the same time, including the addition of salt, (such as NaCl), and glucose, which allows both to increase the yield of the molecules of economic interest, and also to reduce the time needed for stimulation.

In accordance with another characteristic of the present invention, in each of the second photobioreactors the concentrated biomass of algae is exposed to a moderate light intensity, preferably comprised between about 20 pmoles and about 200 pmoles of m V 1 photons, removing the CO 2 .

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a schematic representation of a plant for the cultivation of algae, preferably microalgae, according to the present invention, divided into three processing units;

- fig. 2 is a schematic representation of a first alternative of the second processing unit of the plant in fig. 1 ;

- fig. 3 is a schematic representation of a second alternative of the second processing unit of the plant in fig. 1 ;

- fig. 4 is a schematic representation of a third alternative of the third processing unit of the plant in fig. 1.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. DET AILED DESCRIPTION OF SOME EMBODIMENTS

With reference to fig. 1, a plant 10 according to the present invention for the cultivation of algae, preferably microalgae, for example the Chlorella zofingiensis microalgae, essentially comprises three processing units disposed in sequence, that is, a first processing unit 11 , configured to allow the growth of a biomass of algae, a second processing unit 12, configured to concentrate the biomass of algae exiting from the first processing unit 11 , and a third processing unit 13 configured to transform the concentrated biomass, arriving from the second processing unit 12, into molecules of economic interest, such as for example carotenoids, omega 3, lipids and carbohydrates. Here and hereafter in the description, by the term algae, we also intend to include microalgae.

We must clarify that the plant 10 is not limited to the cultivation of the Chlorella zofingiensis microalgae, since potentially it can also be extended to other species of microalgae, such as for example other species of Chlorella, Haematococcus pluvialis, Dunaliella salina, Nannochloropsis sp, Isochrysis sp. and others.

The first processing unit 11 comprises one or more photobioreactors 14 suitable for the growth of a biomass of algae in a growth medium, or culture medium, by exposure to natural light or artificial light. Each photobioreactor 14 can be of any known type, for example a Drechsel bottle, working on a laboratory scale, or vertical, concentric, spiralized cylinders, panels, horizontal and vertical tubes, open or closed tanks, working on larger scales, or which will be developed in the future.

In particular, each photobioreactor 14 is connected to a first cylinder 15, or another suitable container, containing CO 2 .

In each photobioreactor 14 the algae are kept in optimal conditions for maximum cell proliferation, which are known to those skilled in the art, to obtain maximum productivity of the biomass, with minimum nutrients.

In particular, in each photobioreactor 14 the biomass of algae is insufflated with CO 2 enriched air arriving from the first cylinder 15, or other sources of carbon, preferably in a percentage comprised between about 0.1% and about 25%, for example 5%. The inoculum of the biomass of algae occurs with an initial concentration of the biomass preferably from about 0.2 g/1 to about 0.4 g/1, preferably at a temperature of 22 ± 2°C, even if the biomass and temperature values can vary depending on the species.

By way of non-restrictive example, for the growth of Chlorella zofmgiensis, a growth medium is used, having the reagents listed in the Table 1 below, with the corresponding concentrations.

Table 1. Composition of the growth medium for Chlorella zofmgiensis

Among all these reagents, the fundamental parameter is the concentration of NaNO 3 , which preferably varies from about 0.2 g/1 to about 1.5 g/1. From the tests carried out it was found that the best results were obtained with a concentration of about 0.375 g/1 of NaNO 3 , with which the maximum productivity of biomass was achieved with a lower investment of nutrients. These values of minimum required nutrient concentration can vary depending on the species used.

In these conditions the cultures are kept in a growth defined as “semi- continuous”, since the biomass is collected when its concentration reaches a predefined value, preferably comprised between about 0.7 g/1 and about 1.5 g/1. Indicatively this happens every 2, 3 or 4 days.

Moreover, it is preferable to periodically check that in each photobioreactor 14 the maximum productivity has been reached and, if it has, it is advisable to dilute the corresponding biomass contained therein, in order to be able to use a part of the biomass collected so as to re-inoculate the photobioreactor and the remaining part for the subsequent compaction step.

The second processing unit 12 comprises a compaction apparatus 16, which according to a first embodiment can be a centrifuge of a known type, or a filtration system with membranes or other, or a separation system between the biomass and the growth liquid.

Each photobioreactor 14 is connected to the compaction apparatus 16 by means of a first pipe 17.

According to a first variant, shown in fig. 2, alternatively the compaction apparatus 16 can be similar or identical to the one described in the European patent EP 2.326.409.

According to a second variant, shown in fig. 3, alternatively the compaction apparatus 16 can be a tangential filter of a known type.

By way of example, in the compaction apparatus 16 the biomass of algae, which as we have seen has an initial concentration preferably comprised between 0.7 g/1 and 1.5 g/1 when it leaves the first processing unit 11, is taken to a much higher concentration, preferably comprised between 5 g/1 and 300 g/1, that is, from 0.5% to 30%.

The algae concentrated in this way can therefore be, alternatively, either collected to be used directly as natural fertilizers, animal feed, human nutraceutical, etc., or dried and stored, to be subsequently used for the same purposes, or transferred to the third processing unit 13 (fig 1).

It is also provided that the algae exiting from the compaction apparatus 16 can be treated again in the first processing unit 11 , after adding salt or fresh water, depending on the species.

The third processing unit 13 comprises one or more photobioreactors 18, each of which comprises a container 19 made of a material that can be sterilized, safe for health and resistant to sea water.

The container 19 is provided with an upper aperture 20, connected to the compaction apparatus 16 by means of a second pipe 21, a first nozzle 22 for the introduction of CO 2 , for example arriving from a second cylinder 23, a second nozzle 24 for the injection of chemical components and a third nozzle 25 only for the gases to exit.

In the container 19 there are also at least a first probe 26 to detect the temperature and at least a second probe 27 to detect the pH value.

Inside the container 19 there is a stirring device 28, for example with blades, but this is not binding, which can be driven so as to produce a gentle and continuous stirring of the algae contained therein.

Preferably the biomass is inserted into the container 19 so as to fill it almost completely.

A group of lamps 29, for example LEDs, is provided to selectively illuminate the container 19 and a screening device 30 is present to selectively interrupt the light and create dark conditions in the container 19.

In the photobioreactor 18, regardless of its shape, the concentrated biomass of algae is subjected to specific cultivation conditions or stress, that is, optimized to have an imbalance between the availability of energy for the cells, for example light, and the inability to produce biomass, because the cells are limited in the availability of carbon dioxide and mineral nutrients. Under these conditions, the algae can increase the synthesis of molecules of economic interest, such as for example, but not limited to, carotenoids, omega 3, lipids and carbohydrates.

Preferably the concentrated biomass is processed in the photobioreactor 18 in small volumes, preferably comprised between about 1/10 and 1/100 of the volume of the culture in the first processing step in which the biomass of algae grows in the processing unit 11.

An important characteristic is that it is possible to carry out this treatment at high concentrations, which makes the plant 10 much cheaper, with lower costs for both construction and maintenance, and with the possibility of maximizing the volumes.

The plant 10 is more efficient if the first processing unit 11 is optimized, for example as described above, but it can function, with a lower yield, even without this optimization.

Among the stimuli that can be used to induce the accumulation of molecules, some are known, such as for example, bright light, nutrient deprivation, temperature, pH, addition of salts, addition of organic substrates. One of the characteristics of the present invention is that the combination of several stimuli at the same time, such as for example the addition of salt (e.g., NaCl) and glucose, proves to be effective. This allows to increase the yield of molecules of economic interest, but also to reduce the time necessary for stimulation.

Another characteristic that can be used to induce molecule synthesis is the exposure of the concentrated biomass of algae, preferably with a density from about 5 g/1 to about 300 g/1 of biomass, to a moderate intensity of light, preferably from about 20 pmol to about 200 pmol of m s photons, removing CO 2 .

The carbon dioxide can be removed by different methods, the simplest of which provides to hermetically close the container 19. In this case the available CO 2 will be consumed very quickly.

The mixing of the concentrated biomass of algae to obtain continuous exposure to light can be guaranteed with streams of air without or added with CO 2 or by mechanical mixing, for example by means of the stirring device 28, with pumps, or other. In this way an increase in the accumulation of molecules of economic interest is obtained.

It is clear that modifications and/or additions of parts may be made to the plant as described heretofore, without departing from the field and scope of the present invention.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of plants for the cultivation of algae, preferably microalgae, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.