System for producing microalgae on an industrial and commercial scale

Abstract

The present invention relates to a system for producing microalgae on an industrial and commercial scale including a plurality of leak-tight productive units containing the microalgae culture and nutrients, a pressurized air driving element, a pneumatic circuit which introduces air in the mentioned units, and a hydraulic drive circuit and a hydraulic return circuit which allow circulation between the units with a central manifold, such that the distribution of ducts forming said circuits enables a homogeneity of the content of the leak-tight productive units to assure the production of microalgae on an industrial scale.

Description

[0001] SYSTEM FOR PRODUCING MICROALGAE ON AN INDUSTRIAL AND COMMERCIAL SCALE

[0002] DESCRIPTION

[0003] TECHNICAL FIELD

[0004] The present invention relates to a system for producing microalgae on an industrial and commercial scale which allows natural and functional products to be produced from microalgae, with a number of applications, such as in cosmetics, food, nutraceuticals, biostimulants, phytosanitary products, aquiculture, biofuels, wastewater management, etc. The objective of the invention is to carry out said production of microalgae on an industrial scale in a more efficient and competitive manner than what has been done in the prior art to date, thereby obtaining a product at a competitive cost in an increasingly more demanding market of natural and sustainable products. In this sense, the invention proposes a closed system for producing microalgae which, unlike the existing systems for production considered to be closed, allows an industrial scale to be attained. The key lies in linking together a maximum number of leak-tight productive units (productive unit, PU, is understood to mean the minimum productive element containing a microalgae culture system; this unit can be 1 tube, 1 bag, 1 panel, etc., where the volume of this productive unit varies greatly depending on the productive system, generally between 50 I and 700 I, although it is usually between 300 and 600 I), such that the total volume resulting from linking said productive units together (which in the present invention is referred to as reactor) may reach volumes of between 1.6 m3and hundreds of m3, preferably above 12 m3. Furthermore, the final requirement is for this culture to be completely homogeneous, such that all points of the reactor, and therefore each of the leak-tight productive units, are at the same temperature, pH, microalgae concentration, nutrient concentration, etc. Given these conditions, the microalgae will all be “doing the same thing” (i.e., dividing, excreting, eating, etc.), and it will therefore be possible to control a culture from a few m3to thousands of m3, since there will only be a few tens of reactors to be controlled (instead of thousands of productive units) in an industrial plant of thousands of m3. Furthermore, this must be done with a lower CAPEX and OPEX in order to be competitive.

[0005] Though obvious, this is difficult to extrapolate to an industrial scale, where there will be thousands of productive units and where it will be difficult to group these productive units while achieving a homogeneous culture in each of the productive units that are linked together (reactor). If these productive units are not suitably linked together, it will be impossible to have control over a plant with thousands of m3.

[0006] Therefore, the present invention intends to link together the maximum number of productive units as a reactor to operate and process it with control, but at an acceptable cost, thereby being able to offer a high quality and competitively priced end product, while at the same time optimizing the yield and reducing the production time. The present invention thereby allows a fully standardized (reproducible) product to be offered on the market, in which the quality of the product is always the same.

[0007] With all this, the intention is to respond to the current deficiency of quality products originating from microalgae, since current systems have limitations in terms of the capability to create systems on a commercial and industrial scale, as will be shown in the prior art. Therefore, what is ultimately intended is to keep up with the growing demand for natural, sustainable and functional products, and thus contribute to the development of a more sustainable and environmentally friendly economy. The invention is therefore presented as an innovative and highly efficient solution for the production of microalgae, which is expected to have a great impact on the market and on society in general.

[0008] BACKGROUND OF THE INVENTION

[0009] Currently, the production of microalgae is gaining importance due to the growing demand for natural, sustainable, and functional products on the market; technology is constantly evolving, but the existing barriers have not enabled the industrial leap required by the demand for products of this type. Hence, there is a continuous search for solutions that will definitely allow the necessary leap forward.

[0010] Microalgae are the building blocks of life and the most abundant primary producers of high value-added molecules in nature. In fact, scientists refer to them as the world’s pharmacy, referring to their capacity to provide active ingredients, not only in the field of pharmaceuticals, but also in cosmetics, food, supplementation, etc.

[0011] At present, several technologies are used to produce microalgae, but except for systems based on open ponds, there is currently no technology capable of meeting the requirements demanded by the market; product variety, large volumes, suitable costs and quality.

[0012] This is due to the fact that most of the proposals either require too much capital (closed systems) to be applied, or the product variety and quality is unsuitable (open ponds). Furthermore, productive systems based on closed systems, which could provide product variety and suitable quality, do not reach industrial scales due to the difficulty of taking pilot concepts to commercial scales at reasonable costs; operating costs are too high to produce them at competitive prices and they can only be applied in some areas of the planet where the specific conditions are present.

[0013] Therefore, existing technologies for microalgae production are not capable of producing competitive products, compared to other natural sources, and this is because the design assumptions were wrong and based on a different application (search for alternatives to biofuels). This is making market access difficult for most companies trying to switch activities and enter the market of cosmetics and food / feed, supplementation, etc. In fact, Chlorella and Spirulina are the two types of microalgae that are competitive on the market at the moment, with a really large and profitable market volume, with low CAPEX and OPEX, which are produced with a simple and inexpensive technology Open Ponds) that is widespread in China and India. At this point it is important to note that the quality of products from China and India is far from the standards demanded by the rest of the world, and sooner rather than later the customer will demand much more product in closed systems that guarantee their quality; for the moment, there are no alternatives with closed systems.

[0014] The problem is that alternatives based on closed systems require a lot of capital and it is currently difficult to build profitable plants; this causes most of the plants to remain on a pilot plant scale without progressing to a commercial scale.

[0015] Moreover, not all microalgae can be grown in open ponds, as this system is not suitable for species sensitive to the control of temperature, pH, CO2 concentration, irradiation, or sensitive to contamination. In these cases, closed systems are required, where all these variables can be managed to ensure productivity and quality. Furthermore, the market is demanding purer products with a certain bioactivity, which implies developing more sophisticated systems to produce said products, and open ponds are not the optimal option. The reactors currently being used, either on an industrial or experimental scale, can be classified into two main groups:

[0016] - open ponds;

[0017] - closed reactors, among which horizontal and vertical reactors can be distinguished. Vertical reactors include tubular and panel reactors.

[0018] Open ponds

[0019] Open ponds can be classified as natural water (lakes, lagoons, ponds) and artificial ponds (open ponds). One of the main advantages of open ponds is that they are easier to build (low CAPEX) and operate (low OPEX) than most closed systems. However, the main limitations of open ponds are limited light harnessing by the cells, losses on evaporation, bad weather that can impede algal growth, diffusion of CO2 into the atmosphere, lack of control (of temperature and pH), and the need for large tracts of land. Furthermore, contamination by predators and other fast-growing heterotrophs has restricted commercial production of algae in open culture systems to only those organisms that can grow under extreme conditions. Even so, these more resistant species result in low quality products; the customer is beginning to perceive this and the demand for product produced in Europe in closed reactors is beginning to grow. Also, due to the inefficiency of agitation mechanisms in open culture systems, their mass transfer rates are very poor, resulting in low biomass productivity.

[0020] Ponds in which algae are cultured are often referred to as “raceway ponds” or open ponds. In these ponds, algae, water and nutrients circulate on a raceway. With paddle wheels providing the flow, the algae are kept suspended in the water and circulated back to the surface on a regular frequency. Ponds are usually shallow because the algae need to be exposed to sunlight, and sunlight can only penetrate the pond water up to a limited depth. The ponds operate continuously, with a constant feed of CO2 and nutrients, while the water containing algae is removed at the other end. One of the main problems with this technology is the high levels of contamination due to strains of bacteria or other phototrophic organisms, which often cause undesirable species to take over the desired algae growing in the pond, drastically reducing the homogeneity and reproducibility of the end product. The other major problem with open ponds is temperature control. The large volumes of water in which the algae grow must also be kept at a certain temperature in open-air spaces. This often becomes a difficult and expensive process. Another drawback is the uneven intensity and light distribution within the pond.

[0021] In summary, these open ponds are really simple, with low production costs and relatively low operating costs, but at the same time it is not the most suitable system for mass cultivation of most microalgae species, with there being few strains capable of growing in these systems with optimal yield.

[0022] Closed reactors

[0023] Horizontal closed tubular reactors

[0024] Horizontal closed tubular photobioreactors, described in W02007025145A2, operate in a horizontal arrangement and do not require as much capital as vertical reactors. However, these horizontal reactors have other limitations making them options that are not suitable for all species, such as: difficulties in removing the O2 generated by photosynthesis, which gives rise to photoinhibition problems, high OPEX, low productivity per m2and m3, being viable only in indoor conditions (outdoor conditions generate photoinhibition).

[0025] Vertical closed tubular reactors

[0026] These reactors allow overcoming some of the main obstacles found in open systems, such as the control of system variables (CO2, luminosity, temperature, etc.), the exposure to pollution is lower and a smaller tract of land is required to achieve the same production as in open reactors, especially in the case of a vertical arrangement (higher volume per unit area). (See international PCT patent applications nos. W02007025145A2, W02006020177, WO03094598, and W02007144441). However, all these systems have the problem that their original design corresponds to an approach based on a massive future scaling to be competitive, and this is due to the fact that the origin of these technologies had at the time as their main objective the production of biofuels. These systems are generally capital intensive and their methods are associated with high costs (cleaning, disinfection, evaporation of culture water, energetically deficient due to pumping and extraction). The problem is that the scaling up of these systems has not been carried out, and they have remained in a pilot plant concept, still being developed halfway; it does not allow them to produce biofuels, nor has it allowed them to enter other markets such as nutraceuticals, cosmetics, phytosanitary products, etc., as production costs are not competitive. Therefore, the greater efficiency sought by systems of this type is not enough to be profitable in a competitive market.

[0027] Single bags

[0028] The main (and only) advantages of this system are that it is very inexpensive and easy to implement. On the other hand, the operation is not simple and does not allow scaling up to commercial volumes with guarantees. It is very difficult to control (since it is necessary to control a multitude of productive units) and, therefore, it is not feasible to scale it up or to obtain quality products that are competitive in the market. Furthermore, it should be emphasized that the bag cannot be closed in a leak-tight manner, nor does it allow a mechanization of guarantees to generate a leak-tight system, the only way to work being to expose the culture to the open air, leaving the entire upper section open so that the aeration that enters through the base exits through the upper part.

[0029] Closed vertical flat panel reactor

[0030] Closed flat panel reactors are a type of closed vertical reactor. They are closed and generally simpler than the closed vertical tubular photobioreactors mentioned above. Furthermore, the path length is usually smaller than in others (the ratio of surface area exposed to light with respect to volume is higher), with the photosynthetic yield potentially being higher than in other systems.

[0031] However, like vertical tubular reactors, it presents the problem of scalability; a strategy is needed that allows breaking through the technical barrier to go from a pilot concept to an industrial scale to obtain products at a competitive price. This is what is intended with the present invention, i.e., to bring a system that allows to ultimately scale up the production of microalgae, without losing competitiveness.

[0032] Moreover, it is worth mentioning that international patent application no. W02020136208 discloses a system for producing products from microalgae, the configuration of which, again, does not allow its scaling up to an industrial level. In this sense, the system of the aforementioned patent works perfectly at a pilot scale where personnel is able to control and operate each of the productive units, but it is not possible to generate a homogeneous volume of culture that can represent a volume that can be processed and managed industrially, where the control of what happens in the reactor (sum of productive units) is possible, being possible to anticipate what happens at all times with the culture. This system thereby does not allow maintaining a homogeneous content among the productive units when an assembly with a considerable number of productive units is carried out. If this system were to be taken to an industrial scale, it would be impossible to operate the plant at a reasonable cost, since a large number of personnel would be required, and it has been possible to verify that the system does not offer a competitive product or the required quality from a production of more than 8 m3. Likewise, the system disclosed in document no. W02020136208 necessarily includes a grid that extends over the surface of the productive units to keep them in the vertical position and prevents the reception of light in all of the productive units. Moreover, this system also does not allow the complete filling of the productive units, so that each unit necessarily includes in its upper portion an air pocket that causes, for example, the formation of dead, heterotrophic bodies and, therefore, a possible source of contamination. It is this circumstance that makes it difficult for the productive units to generate a common volume with the rest of the productive units.

[0033] In view of the above, the applicant of the present patent application has detected the need to develop a system that offers a cost-effective and efficient solution for the production of natural and functional products using microalgae, such that said system allows production on an industrial scale, while maintaining the quality of the product obtained.

[0034] DESCRIPTION OF THE INVENTION

[0035] The system for producing microalgae on an industrial and commercial scale to produce natural and functional products proposed in the present invention allows overcoming the drawbacks set forth above, offering a solution that assures production on an industrial scale.

[0036] The developed system thereby allows natural and functional products to be obtained, with natural and functional products being understood to mean those products resulting from the culture of microalgae having a natural origin; they are cellular microorganisms growing according to a photosynthesis process, i.e., they correspond to a natural process that requires nutrients, oxygen, and CO2. There is no artificial process in the processing for it not to be considered a natural product. Moreover, functional products are understood to mean those products resulting from the culture of microalgae providing additional benefits beyond their basic nutritional value. These products are designed to improve health and well-being (regardless of their application, which may be very diverse: food, supplementation, agriculture, cosmetics, aquiculture, etc.).

[0037] Namely, the system is made up of a plurality of leak-tight productive units. In this sense, the assembly of said leak-tight productive units must be considered a single reactor, since the objective sought by the present invention is to provide a homogeneous content in each of the leak-tight productive units.

[0038] The leak-tight productive units are formed by flat vertical units parallel to one another, manufactured in a transparent material and the configuration of which allows them to be completely filled with microalgae culture. In this sense, each of the leak-tight productive units has a maximum height of 2 m and are arranged parallel to one another, leaving sufficient space so that an operator can pass between them and minimize the shadow effect of some panels with respect to others.

[0039] The separation between leak-tight productive units is determined by the shadow effect; in an outdoor system, the distance between panels will be greater than in an indoor installation where LEDs are used, or in the event that it is arranged in a greenhouse in which direct light can be transformed into diffused light and the shadow effect reduced. However, it should be noted that the distance between each leak-tight productive unit can be between 20 cm and 150 cm, preferably between 50 cm and 100 cm.

[0040] In that regard, the means for producing the microalgae culture of the system of the invention are formed by:

[0041] - a plurality of leak-tight productive units, formed by 2nleak-tight productive units, where n is greater than or equal to 5;

[0042] - at least one pressurized air driving element which introduces air and CO2 in the system and generates a turbulent flow in the leak-tight productive units;

[0043] - a pneumatic circuit formed by ducts arranged from the pressurized air driving element to each leak-tight productive unit, such that the entry of each duct is through the lower part of each leak-tight productive unit,

[0044] - a hydraulic drive circuit formed by ducts conveying the microalgae culture, nutrients, air, CO2, and the oxygen generated by the photosynthesis of the microalgae culture, which are arranged connected to the upper part of each leak-tight productive unit;

[0045] - a hydraulic return circuit formed by ducts which are connected to each leak-tight productive unit to recirculate the microalgae culture and nutrients,

[0046] - a central manifold fed by the hydraulic drive circuit with the microalgae culture, nutrients, air, and CO2; the central manifold is connected to the hydraulic drive circuit and to the hydraulic return circuit, the central manifold being provided with a venting element for the exit of the air, CO2, and the oxygen generated by the photosynthesis of the microalgae culture contained in the ducts of the hydraulic drive circuit.

[0047] The central manifold is necessarily located at an elevation above the upper part of the leak- tight productive units, preventing the formation of air pockets in the leak-tight productive units.

[0048] The pneumatic circuit has a maximum elevation arranged above the maximum elevation of the central manifold, thereby preventing the return of fluid when air and CO2 are not being introduced. That is, when air and CO2 are not introduced in the system, the location of the mentioned elevation of the pneumatic circuit prevents the fluid from returning to the pressurized air driving element and / or to the adjacent productive units.

[0049] The ducts of the pneumatic circuit, of the hydraulic drive circuit, and of the hydraulic return circuit have the same distance between the central manifold and the leak-tight productive units, with the distribution of the ducts forming said circuits being symmetrical and in cascade, taking the central manifold as the center of symmetry, generating a homogeneous content of the microalgae culture, nutrients, air, CO2, and O2 from the photosynthesis in all the leak-tight productive units and preventing the formation of dead zones in the system.

[0050] In this sense, the air and the CO2 introduced by means of the pressurized air driving element in the leak-tight productive units feed the microalgae culture. Therefore, as a result of the air and CO2 stream of the pneumatic circuit, the circulation of the fluids involved in the system of the invention is enabled. Preferably, the pressurized air driving element is a gaseous fluid generation means, such as a blower or a compressor. The bubbles that are formed in the microalgae culture by introducing the air and CO2 from the pneumatic circuit have an associated kinetic energy displacing the volume of culture to the upper part, where the outlet ducts or ducts forming the hydraulic drive circuit are arranged, such that an air pocket is not formed in the upper part of the leak-tight productive unit.

[0051] In this sense, the microalgae culture, together with the nutrients, air, CO2, and the oxygen generated by the photosynthesis of the microalgae culture exits the leak-tight productive unit and is combined with another stream coming from another leak-tight productive unit. Therefore, the sum of these flow rates is combined with two other leak-tight productive units and these four are combined with four other leak-tight productive units, and these 8 productive units are combined with 8 other productive units, and so on and so forth in a symmetrical manner.

[0052] This distribution allows confirming that the configuration established for the present invention offers a hydraulic design that assures suitable homogenization of the reactor. It should be noted that the air and CO2 contained in the hydraulic drive circuit passes into the central manifold and through simple physics, exits at the upper part thereof since the central manifold is open at the top in the form of a chimney. Simultaneously, in the central manifold the microalgae culture falls along the vertical of the manifold due to the force of gravity, and starts to the return to each of the leak-tight productive units by means of the hydraulic return circuit.

[0053] It should be noted that, preferably, each leak-tight productive unit has at least two connection points with the hydraulic drive circuit, such that at least two ducts of the hydraulic drive circuit are connected to each leak-tight productive unit at the upper part thereof.

[0054] To enable the hydraulic drive circuit and the hydraulic return circuit to work as described above, in the present invention it is necessary for each leak-tight productive unit not only to be closed, but also to be leak-tight. That is, the side walls, base, and cover perfectly seal the fluid which is contained in the cubicle defined by the transparent material forming same, such that the leak-tight productive unit can be filled to the top without risk of leakage. Preferably, the transparent material of the leak-tight productive units has a path length of between 6 cm and 20 cm, preferably between 8 and 12 cm, i.e., the vertical sheets forming a leak-tight productive unit are located at a distance (path length) of between 6 cm and 20 cm, preferably between 8 and 12 cm.

[0055] It should be emphasized that the presence of the central manifold is vital to achieve homogeneity of the fluid contained in each of the leak-tight productive units, offering an efficiency to the system that is far superior to other known systems when said invention is used for production on an industrial scale (i.e., more than 32 productive units).

[0056] In this sense, the central manifold is the element through which the entire microalgae culture circulates per cycle, where each cycle lasts for a given time depending on the flow rate of the air and CO2 introduced, and allows:

[0057] -Improving the efficiency of CO2 uptake, as the residence time and the turbulence provided to the culture will improve the diffusion of CO2; this is particularly important when the CO2 is purchased, as its price is very high.

[0058] -Scaling the system; working with independent productive units is unfeasible from a technical point of view and does not allow achieving commercial and industrial scales. The system of the present invention allows working in a modular manner that can be extended to as many leak-tight productive units as desired in order to have a controllable number on an industrial scale.

[0059] -Having a single point of contact with the atmosphere which minimizes contamination. In this sense, the larger the reactor (the more leak-tight productive units the system has), the ratio of the surface in contact with the atmosphere with respect to the volume treated decreases.

[0060] -Working at positive pressure, which would make the concept of working in leak-tight conditions real. The microalgae world often talks about closed systems, but they are never really closed systems, and there is always a risk of an external agent entering the reactor. The inclusion of a venting element in the central manifold, for example a vent valve, which only opens when there is positive pressure in the central manifold, minimizes the risk of contamination. In this way, if aerating is not being performed, nothing enters the system because the vent valve remains closed, and when the entry of air in the system is actuated, the air generates a pressure that forces the vent valve to open for degassing the interior thereof, always working at positive pressure. -Centralizing the measurement of parameters of the system to be controlled in the central manifold itself, such that different types of sensors are arranged therein.

[0061] -Using the central manifold as an entry point for nitrates, phosphates, metals, vitamins, etc., since the entire content of the system circulates through the central manifold.

[0062] -Using the central manifold as the sample collection point.

[0063] -Using the central manifold as a harvesting point, causing the level of all the leak-tight productive units to drop at the same time (as they are all connected to one another), such that the same is harvested from all of them.

[0064] Advantageously, the fact that all the leak-tight productive units are completely filled with microalgae culture allows preventing the formation of air pockets, minimizing the fouling effect. Furthermore, the fact that said units are filled to the top allows gaining in effective volume of culture. In this sense, it should again be emphasized that keeping the leak-tight productive units completely filled, i.e., submerged, is possible because the maximum elevation of the central manifold is located at an elevation above the upper part of the leak- tight productive units, with the central manifold being the only point in contact with the outside, reducing contact with O2 by 90% and, therefore, reducing the possibility of any type of environmental contamination.

[0065] Preferably, the height of each of said leak-tight productive units, without being stacked, is comprised between 0.5 and 2 m, preferably between 0.5 and 1.5 m and preferably between 0.8 and 1 .2 m.

[0066] In this sense, the system of the invention offers the following advantages in relation to the increased production (biological yield) which is up to 30% higher with respect to the system protected in document W02020136208. Said increase is due to the following reasons:

[0067] Larger active surface, namely 10% more active surface with respect to the invention of document W02020136208 by dispensing with the grid and having a larger surface exposed to radiation.

[0068] - The leak-tight productive units do not deform due to the strength of the transparent material.

[0069] By working with leak-tight productive units, sterilization agents can be introduced in the central manifold, even in the form of gas, reaching all points of the system, minimizing the maintenance time of the system, minimizing the risk due to contamination, increasing effectiveness.

[0070] - The system is completely submerged, i.e., all the leak-tight productive units are filled to the top and are not in contact with the air. Only a very small part is in contact with the air in the central manifold. The contact with atmospheric air is reduced by more than 90%, and therefore the risk of external contamination is reduced by the same proportion.

[0071] Minimization of the risk of contamination when operating the system at positive pressure, since the presence of the central manifold generates a single point of contact with the atmosphere, which remains closed when venting is not necessary.

[0072] - More effective system volume (at least 10% more), as the leak-tight productive units are completely filled.

[0073] Homogenization of the culture of microorganisms in the entire system by the injection of air and CO2 from the pneumatic circuit and the symmetrical and cascade distribution of the circuits.

[0074] Use of the central manifold as the point through which nutrients are introduced, harvesting is carried out and sensors are included to monitor the production process, since all the fluid in the system circulates through it, allowing greater control of the microalgae culture production process.

[0075] Likewise, the system of the present invention provides a reduction of the CAPEX since: o The productive unit is more cost-effective than the one proposed in the invention of document W02020136208. Specifically, it involves 25% less CAPEX, in addition to also reducing the OPEX. The reduction comes mainly from the reduction in the amount of metal to be used in the leak-tight productive unit. The transparent material (preferably glass) provides mechanical strength and gives the panel shape sought. It requires much less metal profile to shape it. Furthermore, it will reduce a lot of manual work in the plant with the bag, since the bases and covers will come mechanized, ready to assemble the panel that forms the productive unit, without the need to use a bag containing the microalgae culture and nutrients.

[0076] - As compared with other reactors based on tubular glass systems, the cost per m3of the system of the present invention is much lower. - As compared with other reactors based on tubular PMMA systems, the cost per m3of the system of the present invention is much lower.

[0077] It does not require the use of the sparger or injector (with is a perforated tube, commonly known as tubing, connected to the pneumatic circuit designed to be able to create a bubble curtain of air and CO2 gases), the use of which increases labor cost.

[0078] - The operation of the pneumatic circuit prevents the occurrence of preferential paths.

[0079] By avoiding the use of a booster pump, the investment is reduced, which also simplifies the electrical installation of the system. Furthermore, the operating cost and the mechanical damage on the microalgae (some species are sensitive) are minimized.

[0080] Likewise, the system of the present invention provides a reduction of the OPEX since:

[0081] The system of the invention does not require the replacement of consumables, such as polymeric bags containing the microalgae culture, which reduces maintenance costs

[0082] By avoiding the use of plastic bags, using instead a rigid transparent material that defines leak-tight productive units, it avoids problems related to plastic bags such as: punctures, occurrence of porosity, high levels of machining, degradation due to heat, etc.

[0083] Finally, the scalability of the system should be emphasized, since the more leak-tight productive units involved in the reactor that makes up the system, the more optimal it will be. That is, the scalability of the system is enabled. Advantageously, in the system of the present invention it is not necessary for the leak-tight productive units to be completely level (i.e., the foundation does not have to be adjusted to the mm as is required in a system in which each productive unit has its own level), since the level of the water column will be above the level of the leak-tight productive units.

[0084] In view of the above, the system for producing natural and functional products using microalgae enables offering production on an industrial scale, guaranteeing the homogeneity of the content in all the leak-tight productive units in order to obtain a homogeneous product. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] To complement the description being made below and for the purpose of helping to better understand the features of the invention according to a preferred practical embodiment thereof, a set of drawings is attached as an integral part of said description, wherein the following is depicted with an illustrative and non-limiting manner:

[0086] Figure 1 shows a perspective view of the system for producing natural and functional products using microalgae according to a preferred embodiment of the object of the present invention.

[0087] Figure 2 shows in detail a perspective view of a leak-tight productive unit among those involved in the system.

[0088] Figure 3 shows a partial view of the preferred embodiment of the invention depicted in the preceding figures, in which the detail of the elevation of the pneumatic circuit and of the elevation of the central manifold of the system can be seen.

[0089] Figure 4 shows a partial top perspective view of the preferred embodiment of the invention depicted in the preceding figures, in which the elements forming the central manifold of the system can be seen.

[0090] Figure 5 shows a partial top perspective view of the preferred embodiment of the invention depicted in the preceding figures, in which the hydraulic drive circuit and the hydraulic return circuit, among other elements of the system, can be seen.

[0091] Figure 6 shows a partial bottom perspective view of the preferred embodiment of the invention depicted in the preceding figures, in which the hydraulic return circuit, the pneumatic circuit, and the hydraulic drive circuit, among other elements of the system, can be seen.

[0092] Figure 7 shows a view of the distribution of the ducts forming the pneumatic circuit when 32 leak-tight productive units are involved in the system of the invention. Figure 8 shows a view of the distribution of the ducts forming the hydraulic drive circuit when 32 leak-tight productive units are involved in the system of the invention.

[0093] Figure 9 shows a view of the distribution of the ducts forming the hydraulic return circuit when 32 leak-tight productive units are involved in the system of the invention.

[0094] PREFERRED EMBODIMENT OF THE INVENTION

[0095] In view of the mentioned figures, it can be seen that a system of the invention which in a preferred embodiment includes 32 leak-tight productive units (1 ), wherein each leak-tight productive unit (1 ) is formed by a structure involving two vertical sheets (8) of transparent material and at least four pieces (7) of plastic / glass material the attachment of which generates the leak-tightness of the leak-tight productive unit (1 ) and wherein there is at least one support element (9) to keep it in the vertical position, as observed in Figure 2. Preferably, the transparent material of the vertical sheets (8) of each leak-tight productive unit (1 ) has a path length of between 6 and 10 cm. In this sense, path length is understood to mean the thickness occupied by the culture, i.e., the thinner the material of the vertical sheets (8) is, the smaller the path length is.

[0096] In that regard, as illustrated in Figures 1 to 6, the system of the invention is formed by means for producing a microalgae culture involving the following elements:

[0097] - 32 leak-tight productive units (1 ), containing a microalgae culture and nutrients, each of the leak-tight productive units (1 ) having a maximum height of 2 m, wherein said plurality of leak-tight productive units (1 ) are flat vertical units parallel to one another, manufactured in a transparent material and completely filled with microalgae culture.

[0098] - A pressurized air driving element, preferably a blower (6), which introduces air and CO2 in the system and generates a turbulent flow inside the leak-tight productive units (1)-

[0099] - A pneumatic circuit (2) formed by ducts arranged from the pressurized air driving element to each leak-tight productive unit (1 ), such that the entry of each duct is through the lower part of each leak-tight productive unit (1 ).

[0100] - A hydraulic drive circuit (3) formed by ducts conveying the microalgae culture, nutrients, air, CO2, and the oxygen generated by the photosynthesis of the microalgae culture, which are arranged connected to the upper part of each leak-tight productive unit (1). Preferably, as observed in Figure 4, each leak-tight productive unit (1) has four connection points with the hydraulic drive circuit (3), such that there are four ducts (3’) of the hydraulic drive circuit (3) which are connected to each leak- tight productive unit (1) at the upper part thereof.

[0101] - A hydraulic return circuit (4) formed by ducts which are connected to each leak-tight productive unit (1) to recirculate the microalgae culture and nutrients. In this sense, as illustrated in Figure 6, each leak-tight productive unit (1) has a connection point with the hydraulic return circuit (4), which is preferably arranged in the lower part of the leak-tight productive unit (1).

[0102] - A central manifold (5) fed by the hydraulic drive circuit (3) with the microalgae culture, nutrients, air, and CO2; the central manifold (5) is connected to the hydraulic drive circuit (3) and to the hydraulic return circuit (4), the central manifold (5) being provided with a venting element for the exit of the air, CO2 and the oxygen generated by the photosynthesis of the microalgae culture contained in the ducts of the hydraulic drive circuit (3). According to the view of Figure 4, the venting element of the central manifold (5) is preferably provided with a relief valve (10) that enables the exit of air from the system when it is not in the horizontal position, resting while supported on the mouth of the central manifold (5). The inclusion of the relief valve (10) allows the entire microalgae culture to be isolated, protecting it against any external contamination.

[0103] The air and CO2 introduced in the leak-tight productive units (1 ) thereby feed the microalgae culture. The fact that the air and CO2 enters below each leak-tight productive unit and does not immediately exit, following a path until reaching the central manifold (5), is interesting for several reasons: first because this driving force is used to push the microalgae culture and prevent the use of pumps, and 2) because the CO2 introduced in the system has a longer path and the CO2 uptake efficiency will increase. By using this driving force, the use of pumps is prevented.

[0104] In addition to the means for producing the microalgae culture, the system of the invention includes the following elements: - artificial and / or natural illumination means;

[0105] - means for carrying out the harvesting of the microalgae culture produced.

[0106] As observed in Figure 3, the maximum elevation (5’) of the central manifold (5) is located at an elevation higher than the leak-tight productive units (1), preferably at an elevation of at least 0.5 meters, preventing the formation of air pockets in the leak-tight productive units (1). Moreover, the pneumatic circuit (2) has a maximum elevation (2’) arranged above the maximum elevation (5’) of the central manifold (5).

[0107] It is vital for the ducts of the pneumatic circuit (2), of the hydraulic drive circuit (3), and of the hydraulic return circuit (4) to have the same distance between the central manifold (5) and the leak-tight productive units (1), thereby establishing a symmetrical distribution of the ducts forming said circuits, taking the central manifold (4) as the center of symmetry. Furthermore, said distribution is established as a distribution in cascade, as detailed in the explanation corresponding to Figures 7, 8, and 9.

[0108] The advantage that said distribution offers is the generation of a homogeneous content of the microalgae culture, nutrients, air, CO2, and O2 from the photosynthesis in all the leak-tight productive units (1) and preventing the formation of dead zones in the system.

[0109] Therefore, in the preferred embodiment of the invention described, the ducts conveying the microalgae culture, nutrients, air, CO2, and the oxygen generated by the photosynthesis of the microalgae culture of the hydraulic drive circuit (3) have a flow rate equal to the flow rate circulating through the ducts of the hydraulic return circuit (4). Moreover, the flow rate circulating through the central manifold (4) per hour is at least half the volume treated in the system.

[0110] It should be highlighted that, according to the preferred embodiment of the invention, sensors (11 ), such as a level sensor, a pH sensor, a turbidity sensor, a temperature sensor, a CO2 sensor, a viscometer, and / or a conductometer, which allow control and monitoring of the parameters affecting method of production of the natural and functional products from microalgae, are arranged in the central manifold (5). In this sense, the measurement of said parameters in the central manifold, in addition to the guarantee of a homogeneous content circulating through each and every one of the leak-tight productive units (1 ), allows verifying that said production is performed according to the set objectives of maximum quality and homogeneity in the obtained product.

[0111] Moreover, Figures 7, 8 and 9 show the distribution corresponding to the ducts forming the pneumatic circuit (2), the hydraulic drive circuit (3), and the hydraulic return circuit (4), respectively. The mentioned figures are provided by way of illustration to show the distribution of said ducts in an example in which the system is formed by 32 leak-tight productive units (1) (i.e., when n=5, the total number of productive units is 2n).

[0112] In this sense, the air and CO2 from the pressurized air driving element, preferably a blower (6), are conveyed through the ducts of the pneumatic circuit, depicted in Figure 7, to the leak- tight productive units (1), the mixture of gases being controlled and adjusted continuously.

[0113] The distribution proposed in the present invention of the pneumatic circuit (2) allows ensuring a homogeneous distribution of the drive gases to the microalgae culture, and generating a displacement of fluids contained in the leak-tight productive units (1) in the upward direction to thereby create a natural recirculation of the culture. To achieve said purpose, the distribution of the ducts of the pneumatic circuit (2) has the same distance from the central manifold (5) (point of entry of the reactor) to each of the leak-tight productive units (1), or in other words, the distance of the ducts of the pneumatic circuit (2) from the point of entry into the reactor (being understood to mean the point arranged in the same plane, but above the central manifold) to each of the leak-tight productive units (1 ) is the same, being a symmetrical distribution. Furthermore, the distribution of the mentioned ducts respects a symmetry between the branches thereof, with a gradual scale, ensuring proper management of the flow rate. It should be emphasized that in no case is the pneumatic network connected with the central manifold (5).

[0114] In this sense, the ducts of the pneumatic circuit (2) start out from the blower (6) and feed all the leak-tight productive units (1). The point of entry into the system (reactor) must necessarily have the highest elevation with respect to the rest of the circuits forming the system of the invention. In this way, in the event of a mixing gas supply cut (due to pulse injection, power failure, breakage, maintenance, etc.), the elevation defined for the pneumatic circuit ensures the isolation of the microalgae culture in each of the leak-tight productive units (1), mechanically preventing possible cross-contamination. In this sense, the elevation of the central manifold (5) is located above the upper part of the leak-tight productive units (1).

[0115] Next, the distribution illustrated in Figure 7 for the ducts of the pneumatic circuit (2) according to a preferred embodiment in which the system of the invention is formed by 32 leak-tight productive units (1) is described in detail. In the distribution described in detail, levels are defined at different heights that enable the arrangement of the ducts in a symmetrical manner and in cascade with respect to the point of entry into the reactor to ensure the homogeneous distribution of what is contained in the system. In this sense, the following is seen in Figure 7:

[0116] The duct of the pneumatic circuit (2) starts out from the point of entry into the reactor with a section of 90 mm and is divided into 2 to feed on each side 16 leak-tight productive units (1 ) with a preferred section of 75 mm (referred to as level 1).

[0117] Level 1 is divided into 2 to connect with 8 leak-tight productive units (1 ) on each side, with a section of 63 mm (referred to as level 2).

[0118] Level 2 is in turn divided into 2 to connect with 4 leak-tight productive units (1 ) on each side, with a section of 50 mm (referred to as level 3).

[0119] Level 3 is in turn divided into 2 to connect with 2 leak-tight productive units (1 ) on each side, with a section of 40 mm (referred to as level 4).

[0120] Level 4 is in turn divided into 2 to connect with a leak-tight productive unit (1 ) on each side, with a section of 32 mm (referred to as level 5).

[0121] Level 5 is in turn divided into 2 to connect with the 4 inlets of the leak-tight productive unit (1), with a section of 25 mm (referred to as level 6).

[0122] Level 6 is in turn divided into 2 to connect with 2 inlets of the leak-tight productive unit (1), with a section of 20 mm (referred to as level 7).

[0123] The distribution of the ducts of the hydraulic drive circuit (3) is seen in Figure 8. In this sense, the microalgae culture, nutrients, air, CO2, and the oxygen generated by the photosynthesis of the microalgae culture are conveyed through the ducts of the hydraulic drive circuit (3), depicted in Figure 8, and it takes them from each of the leak-tight productive units (1) to the central manifold (5).

[0124] The duct distribution proposed for the hydraulic drive circuit (3) ensures the suitable homogenization and recirculation of the microalgae culture. To achieve said purpose, the distribution of the ducts of the hydraulic drive circuit (3) has the same distance from each of the leak-tight productive units (1) to the central manifold (5). Furthermore, the design of the mentioned ducts respects a symmetry of the branches thereof, with a gradual scale, ensuring proper management of the flow rate.

[0125] Next, the distribution illustrated in Figure 8 for the ducts of the hydraulic drive circuit (3) according to a preferred embodiment where the system of the invention is formed by 32 leak- tight productive units (1) (i.e., when n=5, the total number of productive units is 2n) is described in detail.

[0126] In the distribution described in detail, levels are defined at different heights that enable the arrangement of the ducts in a symmetrical manner and in cascade with respect to the central manifold (5) to ensure the homogeneous distribution in the system.

[0127] In this sense, the following is seen in Figure 8:

[0128] The ducts of the hydraulic drive circuit (3) start out from each of the 32 leak-tight productive units (1), such that 4 ducts exit in the upper part of each of the leak-tight productive units (1 ), 2 outlets with a section of 20 mm are joined together and the other 2 are joined together in the same way (referred to as level 1).

[0129] Two ducts from level 1 of the same leak-tight productive unit (1) are joined together to form level 2 with a section of 25 mm.

[0130] Two ducts from level 2, grouping 2 leak-tight productive units (1), are joined together to form level 3 with a section of 32 mm.

[0131] Two ducts from level 3, grouping 4 leak-tight productive units (1), are joined together to form level 4 with a section of 40 mm. Two ducts from level 4, grouping 8 leak-tight productive units (1), are joined together to form level 5 with a section of 50 mm.

[0132] Two ducts from level 5, grouping 16 leak-tight productive units (1), are joined together to form a duct from level 6 with a section of 63 mm.

[0133] Level 6 is connected to the central manifold (5) with a section of 75 mm.

[0134] Finally, Figure 9 shows the distribution of the ducts of the hydraulic return circuit (4). In this sense, the microalgae culture, nutrients, traces of oxygen, and CO2 from the central manifold (5) are conveyed through the ducts of the hydraulic return circuit (4), depicted in Figure 9, to each of the leak-tight productive units (1).

[0135] The duct distribution proposed for the hydraulic return circuit (4) ensures the suitable homogenization and recirculation of the microalgae culture. To achieve said purpose, the distribution of the ducts of the hydraulic return circuit (4) establishes the same distance from the central manifold (5) to each of the leak-tight productive units (1). Furthermore, the design of the mentioned ducts respects a symmetry between the branches thereof, with a gradual scale, ensuring proper management of the flow rate. In this sense, the following is seen in Figure 9:

[0136] The hydraulic return circuit (4) starts from a duct which is connected to the lower part of the central manifold (5), exits with a section of 63 mm, and is divided into 2 ducts to go on each side of the system, i.e., to the 16 leak-tight productive units (1 ) on each side, with a section of 50 mm (referred to as level 1).

[0137] Level 1 is in turn divided into 2 to connect with 8 leak-tight productive units (1 ) on each side, with a section of 40 mm (referred to as level 2).

[0138] Level 2 is in turn divided into 2 to connect with 4 leak-tight productive units (1 ) on each side, with a section of 32 mm (referred to as level 3).

[0139] Level 3 is in turn divided into 2 to connect with 2 leak-tight productive units (1 ) on each side, with a section of 25 mm (referred to as level 4).

[0140] Level 4 is in turn divided into 2 to connect with a leak-tight productive unit (1 ) on each side, with a section of 20 mm (referred to as level 5).

[0141] In this sense, as has been described in detail in this preferred embodiment of the invention, the proposed distribution of the circuits involved in the system prevents the formation of air pockets in the leak-tight productive units (1) based on a distribution of the ducts forming said circuits that is symmetrical and in cascade, taking the central manifold (5) as the center of symmetry. Likewise, the proposed system assures a homogeneous content of the microalgae culture, nutrients, air, CO2, and O2 from the photosynthesis in all the leak-tight productive units (1) and, advantageously, prevents the formation of dead zones in the system.

Claims

CLAIMS1 . A system for producing microalgae on an industrial and commercial scale, characterized in that it comprises:- means for producing a microalgae culture comprising: o a plurality of leak-tight productive units (1), formed by 2nleak-tight productive units, where n is greater than or equal to 5, and wherein the leak-tight productive units (1) contain a microalgae culture and nutrients, each of the leak-tight productive units (1 ) having a maximum height of 2 m, wherein said plurality of leak-tight productive units (1 ) are flat vertical units parallel to one another, manufactured in a transparent material and completely filled with microalgae culture; o at least one pressurized air driving element which introduces air and CO2 in the system and generates a turbulent flow in the leak-tight productive units (1); o a pneumatic circuit (2) formed by ducts arranged from the pressurized air driving element to each leak-tight productive unit (1), such that the entry of each duct is through the lower part of each leak-tight productive unit (1), o a hydraulic drive circuit (3) formed by ducts conveying the microalgae culture, nutrients, air, CO2, and the oxygen generated by the photosynthesis of the microalgae culture, which are arranged connected to the upper part of each leak-tight productive unit (1 ); o a hydraulic return circuit (4) formed by ducts which are connected to each leak-tight productive unit (1) to recirculate the microalgae culture and nutrients, o a central manifold (5) fed by the hydraulic drive circuit (3) with the microalgae culture, nutrients, air, and CO2; the central manifold (5) is connected to the hydraulic drive circuit (3) and to the hydraulic return circuit (4), the central manifold (5) being provided with a venting element for the exit of the air, CO2, and the oxygen generated by the photosynthesis of the microalgae culture contained in the ducts of the hydraulic drive circuit (3); artificial and / or natural illumination means;means for carrying out the harvesting of the microalgae culture produced, wherein the air and the CO2 introduced in the leak-tight productive units (1) feed the microalgae culture; the maximum elevation (5’) of the central manifold (5) is located at an elevation above the upper part of the leak-tight productive units (1), preventing the formation of air pockets in the leak-tight productive units (1); whereas the pneumatic circuit (2) has a maximum elevation (2’) arranged above the maximum elevation (5’) of the central manifold; the ducts of the pneumatic circuit (2), of the hydraulic drive circuit (3), and of the hydraulic return circuit (4) have the same distance between the central manifold (5) and the leak-tight productive units (1), with the distribution of the ducts forming said circuits being symmetrical and in cascade, taking the central manifold (5) as the center of symmetry, generating a homogeneous content of the microalgae culture, nutrients, air, CO2, and O2 from the photosynthesis in all the leak-tight productive units (1) and preventing the formation of dead zones in the system.

2. The system for producing microalgae on an industrial and commercial scale according to claim 1 , characterized in that the pressurized air driving element is a gaseous fluid generation means such as a blower (6) or a compressor.

3. The system for producing microalgae on an industrial and commercial scale according to claim 1 , characterized in that each leak-tight productive unit (1 ) has at least two connection points with the hydraulic drive circuit (3), such that at least two ducts (3’) of the hydraulic drive circuit (3) are connected to each leak-tight productive unit (1) at the upper part thereof.

4. The system for producing microalgae on an industrial and commercial scale according to claim 1 , characterized in that the ducts conveying the microalgae culture, nutrients, air, CO2, and the oxygen generated by the photosynthesis of the microalgae culture of the hydraulic drive circuit (3) have a flow rate equal to the flow rate circulating through the ducts of the hydraulic return circuit (4).

5. The system for producing microalgae on an industrial and commercial scale according to claim 1 , characterized in that the leak-tight productive unit (1) is formed by a structure involving two vertical sheets (8) of transparent material and at least four pieces (7) of plastic / glass material the attachment of which generates the leak-tightness of the leak-tightproductive unit (1 ) and wherein there is at least one support element (9) to keep it in the vertical position.

6. The system for producing microalgae on an industrial and commercial scale according to claim 5, characterized in that the transparent material of the vertical sheets (8) of the leak- tight productive unit (1) has a path length of between 6 and 10 cm.

7. The system for producing microalgae on an industrial and commercial scale according to claim 1 , characterized in that the venting element of the central manifold (5) is provided with a relief valve (10).

8. The system for producing microalgae on an industrial and commercial scale according to claim 1 , characterized in that sensors (11 ), such as a level sensor, a pH sensor, a turbidity sensor, a temperature sensor, a of CO2 sensor, a viscometer, and / or a conductometer, are arranged in the central manifold (5).

9. The system for producing microalgae on an industrial and commercial scale according to claim 1 , characterized in that the flow rate circulating through the central manifold (5) per hour is at least half the volume treated in the system.

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