Floating system for producing microalgae in the form of biofilm

Abstract

Title: Floating system for producing microalgae in the form of a biofilm The invention relates to a system (1) for producing microalgae in the form of a biofilm comprising a frame (100), a motor (200), at least one support (300) and a sheet (400) intended to receive the biofilm and in which: the frame (100) is configured to support the motor (200), the motor (200) is configured to impart a rotational movement to at least one support (300); the at least one support (300) is configured to have a rotational movement around an axis of rotation and to support and impart the rotational movement on the sheet (400); the sheet (400) is configured to at least partially surround the at least one support (300), characterized in that the support (300) is configured to have a non-negative buoyancy a liquid (2). Figure for abstract: Fig. 6

Description

Title of the invention: Floating system for producing microalgae in the form of biofilm Technical field

[0001] The present invention relates to the field of microalgae cultivation. It finds particularly advantageous application in the field of microalgae cultivation in the form of biofilm. STATE OF THE ART

[0002] There are several types of microalgae and their cultures are different. For example, there are planktonic microalgae and microalgae organized in biofilm. The present invention aims to produce a system allowing the culture of microalgae in the form of biofilm exclusively. Indeed, the methods for harvesting and treating microalgae cultivated in biofilm are completely different and incompatible with the techniques for cultivating microalgae in planktonic form (i.e., free in water). In fact, the techniques for producing planktonic microalgae are cultivated in suspension in a liquid medium, which is incompatible with a culture in the form of biofilm.

[0003] One of the techniques for cultivating microalgae in the form of a biofilm is disclosed in document WO2015007724 AL. This document discloses a system comprising a frame, a water basin, rollers for driving a biofilm and a motor for driving the rollers. The objective of this document is to improve the cultivation of microalgae in the form of a biofilm by allowing regular exposure to natural and / or artificial light of all the cells of the biofilm. To do this, the rollers are fixed to the frame which is itself fixed to the basin at variable immersion depths. The biofilm is driven by the different rollers from the submerged part of the basin to an emerged part.

[0004] The system disclosed in this document is very cumbersome to implement in that it requires a complex, bulky, massive and therefore costly and energy-intensive structure.

[0005] An object of the present invention is therefore to propose a system allowing the cultivation of microalgae in the form of a biofilm which can be more easily implemented.

[0006] Other objects, features and advantages of the present invention will become apparent from a consideration of the following description and accompanying drawings. It is understood that other advantages may be incorporated. SUMMARY

[0007] To achieve this objective, according to one embodiment, a system is provided for the production of microalgae in the form of a biofilm comprising a frame, at least one support and a sheet intended to receive the biofilm and in which: • the frame is configured to receive the at least one support, • the at least one support is configured to have a rotational movement around an axis of rotation and to support and impart the rotational movement to the sheet; • the tablecloth is configured to at least partially surround the at least one support, and wherein at least one of the support and the frame is configured such that the system has non-negative buoyancy in a liquid.

[0008] By having, for example, a floating support and / or frame, the system is lighter and more easily assembled and disassembled. This reduction in mass includes as a first advantage the limitation of energy consumption for the movement of the supports. In addition, the control of the temperature by evapotranspiration of the biofilm is made possible by the thermal inertia of the mass of the liquid on which the system floats. This allows better control of the temperature by evapotranspiration of the biofilm and savings in energy consumption. Finally, the water becomes the supporting structure of the system, this reduces the need to create a large structure and allows a lightening of the system as a whole as well as a simplification of its implementation and a reduction in costs.

[0009] Optionally, the system is configured so that the support and the sheet form an assembly having non-negative buoyancy. BRIEF DESCRIPTION OF THE FIGURES

[0010] The aims, objects, as well as the characteristics and advantages of the invention will emerge more clearly from the detailed description of an embodiment thereof which is illustrated by the following accompanying drawings in which:

[0011] [fig. 1] Figure 1 represents a first embodiment of the system comprising a sheet stretched by several supports, and in which the supports are horizontal and float in a liquid.

[0012] [fig.2] Figure 2 represents an embodiment of the system similar to that of Figure 1 but in which said system is completely immersed and floats in suspension in a liquid.

[0013] [fig.3] Figure 3 represents an embodiment of the system comprising several supports in which the supports are horizontal and float on the surface in a liquid and in which the water table is distended.

[0014] [fig.4] Figure 4 represents an embodiment comprising several supports in which the supports are vertical and float in a liquid, and in which each support supports its own sheet.

[0015] [fig.5] Figure 5 represents an embodiment of a system comprising a motor powered by the movement of waves on the liquid.

[0016] [fig.6] Figure 6 shows an embodiment comprising a single support floating on the surface of a liquid and in which the frame supporting the motor is fixed to a solid surface. The impression of movement on the support is transmitted from the motor to the support, in particular by means of a belt.

[0017] [fig.7] Figure 7 shows an embodiment of the system in which the motor is included in the support.

[0018] The drawings are given as examples and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily on the scale of practical applications. DETAILED DESCRIPTION

[0019] Before beginning a detailed review of embodiments of the invention, optional features which may possibly be used in combination or alternatively are set out below: • the system is configured to be at least partially immersed in the liquid; • the system is configured to be fully submerged in the liquid and have zero buoyancy; • the system comprises a movement module configured to allow the system to alternately take a position completely immersed in the liquid and a partially immersed position; • the at least one support is substantially cylindrical and is preferably taken from a roller or a sausage; • the axis of rotation of the support is parallel to the longitudinal dimension of the support; • the system comprises a motor configured to impart rotational movement around a rotation axis of the support; • the displacement module comprises at least one ballast configured to vary and stabilize the buoyancy of the system in the liquid. • the at least one ballast is arranged in the at least one support; • the system comprises several supports configured to be driven by at least one motor; • the system includes several supports configured to be driven by several engines; • the system comprises several supports and at least one sheet and in which each of the supports is configured to support and print its movement on at least one sheet; • the system comprises several supports and a number of sheets equal to the number of supports in which each of the supports is configured to support and print its movement on a single sheet; • the system includes a single support and a single tablecloth; • the motor is a power device configured to recover energy from the movement of waves on the surface of the liquid; • at least one support is inflatable; • the axis of rotation of the at least one support is substantially horizontal; • the axis of rotation of the at least one support is substantially vertical.

[0020] Buoyancy is the vertical thrust, directed from bottom to top, that a fluid exerts on an immersed volume. Buoyancy always acts in the opposite direction to gravity.

[0021] Buoyancy can be zero, that is to say that gravity and pressure on the object are equal to Archimedes' thrust. In this case the object is suspended in the fluid.

[0022] Buoyancy can be negative, meaning that gravity and pressure exert a force greater than Archimedes' thrust. In this case the object sinks into the fluid and sinks.

[0023] Finally, buoyancy can be positive, meaning that gravity and pressure exert a force less than Archimedes' thrust. In this case the object rises in the fluid.

[0024] It is specified that in the context of the present invention, the verb "to float" is understood by its definition in that it allows an object to be carried by a liquid, and that it can remain on the surface or in suspension "between two waters" without sinking. That is to say that the object has a non-negative buoyancy in this liquid.

[0025] It is known that buoyancy is in particular a function of the density of the object relative to the density of the fluid in which it is totally or partially immersed.

[0026] Finally, it is specified that "engine" means an organ transforming energy of a different nature into mechanical energy. For example, the engine can be powered by kinetic energy such as the movement of waves or even the wind, by electrical energy, thermal energy or any other type of energy. The engine can, for example, take the form of a mill, a turbine, or any other form allowing the transmission of mechanical movement with input energy.

[0027] System 1 for the production of microalgae in the form of biofilm according to the The present invention comprises at least one frame 100, a motor 200, at least one support 300 configured to float in a liquid 2 and support a sheet 400, the sheet 400 is configured to support microalgae in the form of a biofilm. The motor 200 is configured to cause movement on the support 300 and consequently on the sheet 400.

[0028] Advantageously, system 1 allows the cultivation of any type of microalgae, and preferably at least one of the following varieties: Tisochisis lutea, Chlorella vulgaris, Navicula sp, Tetraselmis sp, Phaeodactylum tricomutum.

[0029] The system 1 may also comprise at least one spraying device 500.

[0030] The system 1 is exposed to a light source 3. The sheet 400 comprises several portions. Thus, certain portions of the sheet 400 are in a direct exposure zone 3a allowing them to be exposed directly to the light source 3 while other portions are in an indirect exposure zone 3b not allowing them to be directly exposed to the light source 3. The portions of the sheet 400 in the indirect exposure zone 3b benefit from reduced or even non-existent brightness.

[0031] The system 1 is configured so that the movement of the support 300 allows the different portions of the sheet 400 to pass from the direct exposure zone 3a to the indirect exposure zone 3b and vice versa.

[0032] When the system 1 is partially submerged, the system 1 is preferably configured so that the portions of the sheet 400 are successively in a submerged position and in an emerged position. This alternation of submerged / emerged position is carried out at a more or less regular and preferably regular frequency. This is notably illustrated in Figures 1, 3, 5 and 6. In these embodiments, the system 1 may have between 0% and 99% of its surface emerged and preferably close to 95% of its surface emerged and preferably close to 99% of its surface emerged.

[0033] In certain embodiments, the immersion is total as illustrated in FIG. 2. In other embodiments as illustrated in FIG. 4, parts of the support 300 are always immersed or emerged, and spraying devices 500 moisten the emerged parts. These different embodiments and their designs are detailed below. The 100 building

[0034] Advantageously, the frame 100 is configured to support at least the motor 200. In certain embodiments, such as presented for example in FIGS. 1 to 4, the frame 100 additionally connects the supports together.

[0035] The frame 100 can be fixed on a rigid surface, as shown in FIG. 6 for example, or completely supported by at least one support 300, as shown in figures 1 to 4 for example or even be supported in part by at least one support 300 and by a rigid surface, not shown in the figures.

[0036] The frame 100 may advantageously comprise a hollow shape filled or not with a gas or a low-density foam. This characteristic makes it possible to increase the buoyancy of the system.

[0037] In the embodiments presented in Figures 1 to 4, the frame 100 comprises side members 110. The side members 110 make it possible to maintain between them, in particular, a plurality of supports 300 and / or at least one ballast 310 or at least one float 320. When the system comprises several supports 300, the frame 100 is advantageously configured to maintain the spacing between the different supports 300, for example at a substantially regular and preferably fixed distance. Maintaining the supports 300 at a regular and preferably fixed distance is preferably achieved by the side members 110. By way of example, the supports 300 and / or at least one ballast and / or float are fixed to the side members 110.

[0038] In Figure 4 in particular, the frame 100 comprises at least one compartment making it possible to frame the support 300.

[0039] The frame 100 may comprise, in the embodiments where a single sheet 400 covers several supports 300, as illustrated for example in Figures 1 to 3, devices for guiding the sheet 400 (not shown in the figures). These devices make it possible, for example in Figures 1 and 2, to bring the sheet 400 closer to the frame 100. This makes it possible, for example, to more easily control the total volume of the system. The support 300

[0040] The system comprises, according to a first possibility, a support. The system comprises a support 300 and, according to a second possibility, the system comprises several supports 300. The remainder of the description refers to a support without being limiting and can apply to all the supports.

[0041] The support 300 is configured to float in a liquid 2. This means that the support 300 floats on the surface or between two waters. By floating on the surface is meant when at least a portion of the support 300 is emerged. The support 300 is configured to impart its movement to at least one sheet 400.

[0042] The support 300 is advantageously cylindrical in shape and / or axially symmetrical and / or substantially conical. The support comprises an external surface. The external surface extends along the longitudinal dimension. The longitudinal dimension of the support 300 is understood to mean its largest dimension or also called its longitudinal extension axis. The support comprises two lateral surfaces corresponding to its bases at the ends of the external surface. The two lateral surfaces and the external surface define an interior volume. Preferably, the lateral surfaces are of the same dimension and the same shape.

[0043] The external surface is configured to receive the sheet 400. The external surface is intended to be at least partially covered with a sheet 400. The external surface may comprise means for adhering and / or fixing the sheet 400. For example, without limitation, the external surface may comprise successions of cavities and roughnesses making it possible to increase the adhesion with the sheet 400. Fixing means may, for example and without limitation, be a surface with bridges configured to cooperate with hooks carried by the sheet 400. The fixing and adhesion elements may be diverse and varied and are not limited to the examples above.

[0044] The support 300 is advantageously a roller.

[0045] The support 300 is advantageously an inflatable sausage.

[0046] The movement of the support 300 is preferably a rotation about an axis of rotation. Advantageously, the axis of rotation of the support 300 is arranged parallel to the longitudinal dimension of the support 300. Preferably, the axis of rotation passes through the center of each of the lateral surfaces.

[0047] In one embodiment of the invention, the support 300 comprises a length of between 2 and 100 meters and preferably between 5 and 50 meters. For example, the support 300 has a diameter of between 0.10 and 3 meters and preferably between 0.5 meters and 1.5 meters.

[0048] Advantageously, the support 300 is made of an impermeable material such as polyvinyl chloride for example.

[0049] Preferably, the support 300 is made of a flexible inflatable material such as a fabric for example. In this embodiment, the pressure inside the support 300 is greater than 10 millibars (mBar), and preferably greater than 30 mBar. This advantageous construction makes it possible to improve the mass reduction of the support 300. Thus, the energy required to set the support 300 in motion is greatly reduced. In addition, the inflatable support 300 allows for easier assembly, disassembly, transport and storage of the entire system 1.

[0050] According to one possibility, the support 300 is permeable to gas, in particular to carbon dioxide (CO2) to allow the diffusion of CO2 from the support to the algae biofilm. According to another possibility compatible with the previous one, the support 300 is permeable to a concentrated nutrient medium. In this possibility, the nutrient medium is stored in the support 300.

[0051] In one embodiment, the interior volume of the support 300 is full. In this embodiment, the interior volume of the support 300 is filled with a material allowing its flotation such as, for example, polyester or polystyrene foam. It is possible to vary the buoyancy of the support 300 by varying the density of the foam. Indeed, the lower the density of the foam, the greater the buoyancy of the support. 300 will be high. On the other hand, with a foam having a higher density, the buoyancy of the 300 support will be reduced.

[0052] In another embodiment, the interior volume of the support 300 is hollow and filled with gas, preferably under pressure (pressure greater than 10 mbar). In this embodiment, the buoyancy of the support 300 is variable depending on the quantity of pressurized gas injected into the interior volume of the support 300. The embodiment has the advantage of being easily implemented and transportable. The support 300 is advantageously inflatable. The support 300 advantageously has sufficient rigidity to ensure transmission of the rotational movement over its entire longitudinal dimension. The support 300 preferably has a hardness allowing the scraping of the algal biofilm present on the surface of the sheet.

[0053] In this embodiment, the support 300 may comprise devices configured to function as a ballast. For example, the support 300 may comprise at least one valve and / or at least one air pump and / or a water pump for varying the volume of gas inside the support 300. This variation may for example allow the system 1 to vary its buoyancy between positive buoyancy, i.e. the support is partially submerged, for example with less than 5 centimeters of the support 300 submerged, and zero buoyancy, i.e. the support 300 is in equilibrium in a liquid, i.e. it is, according to the expression, the support 300 is suspended in a liquid "between two waters". The transition from a partially emerged position to a totally submerged position may be achieved by granting the system 1 negative buoyancy.Such negative buoyancy is transient and is only intended to vary the immersion of the system 1. In the case where the support 300 is in equilibrium in a liquid, the entire support can be submerged or at any intermediate position. This variation can make it possible to adapt the production conditions of the microalgae according to their needs for air, light or liquid 2. Similarly, in the case of installation in a natural environment such as for example at sea or in a lake, immersing the system 1 in the event of difficult weather conditions such as strong winds or significant swell, for example total immersion, can make it possible to avoid damage to the system.

[0054] In another embodiment of the invention, the support 300 has a fixed density and the system comprises at least one ballast 310 or at least one float 320 advantageously positioned on the frame 100.

[0055] According to one embodiment, the support 300 is arranged so that its longitudinal dimension is vertical. By vertical is meant parallel to the direction of gravity. According to another embodiment, the support 300 is arranged so that its longitudinal dimension is horizontal. By horizontal is meant the direction normal to the vertical.

[0056] The mass of the support 300 is advantageously between 2 and 50 kilograms per m2 of footprint and preferably between 5 and 20 kilograms per m2 of footprint.

[0057] In some embodiments, the system includes multiple supports 300 as shown as examples in Figures 1-4.

[0058] In these embodiments, the supports 300 can be positioned substantially horizontally (FIG. 1 to 3) or substantially vertically (FIG. 4). The supports 300 are preferably, but not limited to, substantially parallel to each other.

[0059] In these embodiments, the supports 300 are held together by means of the frame 100. The holding is preferably carried out by at least one of the lateral faces of the supports 300 and perhaps carried out by both faces.

[0060] In the embodiment illustrated in Figure 4 and in which the supports 300 are vertical, the supports 300 may comprise ballasts on and / or in their submerged parts. The ballasts are configured to stabilize the supports 300. Ballast 310 and float 320

[0061] A ballast is a device equipped with means for varying its buoyancy. Conventionally, a ballast can vary the pressure of a gas or the proportion of gas / liquid in its internal volume in order to modify its own buoyancy and the buoyancy of the system to which it is connected. In certain embodiments equipped with at least one and preferably several ballasts 310, the latter may or may not communicate with each other. Thus, each ballast 310 can communicate its buoyancy to the other ballasts 310, or to an external buoyancy management module of the system 1. The communication can also be a fluid communication making it possible to vary the levels of gas / liquid present in the ballasts 310 between them. This makes it possible in particular to vary the buoyancy of only a part of the system 1 in order, for example, to modify the trim of the system.In other words, to vary the inclination of the system relative to a plane comprising the surface of the liquid 2. A ballast 310 can be configured to have the role of both float and ballast. In its ballast function, the ballast 310 allows better stability of the floating system 1.

[0062] A float 320 is a floating device for improving the buoyancy of the system 1. Its buoyancy is fixed. This is the case, for example, of a buoy. To do this, the float 320 is either filled with a gas or with a low-density foam. Advantageously, the float 320 is fixed to the frame 100. Tablecloth 400

[0063] The sheet 400 is configured to at least partially cover the support 300 and more preferably the external surface of the support 300. The support 300 and the sheet may be one and the same element. The sheet 400 is configured to allow the attachment of the microalgae in the form of a biofilm. For this purpose, the sheet 400 is either configured to directly receive the algae biofilm or the sheet 400 comprises a coating that can be formed by a complementary sheet at least partially covering the sheet 400. The complementary sheet is configured to receive the algae biofilm. The sheet 400 is at least partially under the surface of the liquid 2. The sheet 400 comprises several portions, at least some portions of which are submerged. There may also be emerged parts. The submerged and emerged parts vary depending on the time and the movement of the sheet 400.

[0064] Advantageously, the microalgae have a thermal preference, that is to say that the temperature of the medium in which they are cultivated has a direct influence on their growth rate.

[0065] Thus, if the temperature is too low or too high relative to their thermal preference, the growth of the microalgae slows down or the population decreases.

[0066] In fact, it is preferable to maintain a stable temperature during the growth of the microalgae.

[0067] It should be noted that two mechanisms contribute to maintaining the temperature within a thermal preference compatible with growth, and in any case avoiding lethal temperatures: evapotranspiration and the thermal inertia of the body of water in which the system 1 floats. Advantageously, alternating the immersion and emersion of the water table 400 allows for better control of the thermal preference of the microalgae habitat.

[0068] In some embodiments, the sheet is entirely immersed in the liquid 2 but retains neutral or positive buoyancy.

[0069] Preferably, the two ends of the sheet 400 are connected together to form a loop. In another non-preferred embodiment of the invention, each of the ends of the sheet 400 is fixed to the external surface of a support 300 and is therefore immobile relative to the support.

[0070] The sheet 400 comprises a first face 410 and a second face 420. The first and second faces 410, 420 can be produced by a single layer or by several layers superimposed on each other.

[0071] The first face 410 is opposite at least one support 300. The first face 410 is configured to allow contact and adhesion with said support 300. The first face 410 is preferably made with a material allowing adhesion to the support 300 such as for example a fabric, a canvas, a polyester or polyurethane sheet, etc. The adhesion can, for example, be achieved by friction, or even with asperity / cavity alternatives in the first face 410. However, any other material allowing the production of a sheet 400 can be used for this face.

[0072] The adhesion of the first face 410 to the support 300 allows said support 300 to impart its movement to the sheet 400. Thus the sheet 400 is movable at least relative to the frame 100. In certain embodiments such as presented in FIGS. 1 to 3, the sheet 400 is also movable relative to the support 300.

[0073] In these embodiments, the first face 410 is configured to adhere sufficiently to the support 300 in order to allow the transmission of the movement of the support 300 to the sheet 400 while allowing mobility of the sheet 400 with respect to said support 300. In other embodiments such as presented for example in FIGS. 4 and 6, the first face 410 is fixed relative to the support 300. In these embodiments, the first face 410 then comprises elements for fixing to the support 300. The fixing elements may for example be an adhesive, a bridge-shaped surface cooperating with a surface comprising hooks on the support 300, staples, nails, screws or any other element allowing fixing between the sheet 400 and the support 300. Advantageously, the fixing is reversible in order to be able to separate the sheet 400 and the support 300.

[0074] The second face 420 is configured to be on the opposite side to the first face. The second face 420 is either configured to allow the microalgae to be fixed in the form of a biofilm or to receive a preformed coating of a complementary sheet capable of receiving the algae. The second face 420 advantageously has no contact with the support 300. Advantageously, the material used to fix the microalgae in the form of a biofilm is preferably rough and has cavities or microcavities. For example, the second face may be made of one of the following materials: cotton, burlap, polyethylene, polyurethane, biopolymer or even polyester.

[0075] In one embodiment, the first and second faces 410; 420 of the sheet 400 are spaced apart from each other in order to form an internal volume. In this embodiment, a gas is injected into the internal volume in order to inflate the sheet 400. According to a possibility compatible with the previous one, a nutrient medium is injected into the internal volume. The sheet 400, and more particularly the second face 420, is then porous to the nutrient medium in order to feed the microalgae. This embodiment makes it possible to improve the buoyancy of the system 1 by adding a volume of gas to the system. In this embodiment, the sheet 400 comprises at least one device, such as for example a valve and / or an air pump, making it possible to vary the quantity of gas in the internal volume in order to be able to vary the buoyancy.

[0076] In an embodiment comprising several supports 300, a single web 400 may surround several supports 300 so as to form a conveyor belt. In this embodiment, the web 400 may be tensioned at least partially between the supports 300, as illustrated in figures 1 and 2, or be distended between the supports 300 such as in figure 3. In this particular embodiment, the system 1 comprises tensioning elements of the sheet 400. The tensioning elements of the sheet 400 are configured to allow the sheet 400 to be tensioned in order to facilitate the scraping of the microalgae. An advantage of this solution is to increase the culture surface for a given system 1.

[0077] In another embodiment, as illustrated for example in Figures 4 and 6, each support 300, when there are several, is completely surrounded by a single sheet 400. This advantageous solution makes it possible, for example, to vary the characteristics of the sheets 400 depending on the type of production on each of said sheets 400. The sheet 400 is configured to allow the scraping of the microalgae. Thus, even in the case where the sheet is stretched, the tensioning elements make it possible to ensure scraping. The 200 engine

[0078] The motor 200 is configured to print on the at least one support 300 a rotational movement relative to the frame 100. The frame 100 receiving the motor forms a reference frame relative to the movement of the support.

[0079] The motor is configured to have a preferential rotational movement at its output.

[0080] Preferably, the motor 200 is connected to at least one of the side surfaces of the support 300. The system 1 may comprise a single motor 200 or a plurality of motors 200 for one or more supports 300.

[0081] For example, as illustrated in Figure 1, the system 1 comprises a single motor for several supports 300. In Figure 2, for example, the system 1 comprises several motors 200 for several supports 300. In Figure 4, the system 1 comprises one motor per support 300. Finally, in Figure 6, a single motor 200 is present on a single support 300. Other combinations are of course possible, for example and not limited to, having several motors 200 per support 300, in particular connected to each of the lateral surfaces of the support 300.

[0082] Figure 6 shows an embodiment of the connection between the motor 200 and the support 300. In this embodiment, a guide arm 210 holds the support 300 in position at its axis of rotation at a predefined distance from the motor 200. A connecting device 220 provides a connection between the motor 200 and a lateral surface of the support 300. The connecting device 220 may, for example, be a belt, a cable, a rack or even a toothed wheel or any other connecting element. The connection may, for example, be provided by means of a disc positioned as a protrusion from said lateral surface or a toothed wheel (not shown in the figure). The connecting device 220 allows the transmission of the rotational movement of the motor 200 to the support 300. The connecting device 220 may be replaced by a chain for example. In this embodiment, the arm 210 does not support the support 300 and only has a guiding function. Said support 300 is supported by the liquid thanks to its buoyancy. The guide arm 210 only has a guide function 210 allowing the positioning of the connecting device 220 and the transmission of the movement.

[0083] Other embodiments are of course possible. For example, the output of the motor 200 can be directly connected to a lateral surface of the support 300 as illustrated for example in Figures 1 to 5. In these embodiments, the connection between the motor 200 and the support 300 can for example be made through pinions, but also by means of rollers resting on the support 300 or any other means making it possible to transmit the movement of the motor 200 to the support 300.

[0084] For example, in one embodiment, the frame 100 can be mounted to rotate freely inside the support 300. In this case, the motor 200, supported by the frame 100, can be configured to have an output connected to the internal face of the support 300 and thus cause the support 300 to rotate relative to the frame 100, thanks to the connecting device 220. This solution makes it possible to have a system with minimal bulk. An example of this embodiment is visible in FIG. 7. In this embodiment, the motor 200 is associated with a ballast and is enclosed inside the support 300. Preferably, the support 300 is rigid, either due to the composition of its materials or due to its internal pressure. In addition, the support 300 is preferably sealed and comprises, along its internal wall, a connecting device 220 in the form of a rack and / or a cable.The motor 200 being configured to cooperate with the rack and / or the cable and rotate the support 300. The weight of the motor is configured to rotate the structure. A connection with a sealed rotating collector makes it possible to bring electricity to the motor 200 inside the support 300.

[0085] Preferably, the motor 200 is an electric motor comprising a stator and a rotor. The stator is preferably fixed to the frame 100. The rotor connected directly or indirectly to the support 300 allows the rotation of said support 300 relative to the frame 100. The motor 200 can also be solely mechanical as illustrated in FIG. 5. The storage and restitution of energy is done for example through at least one spring configured to release its energy over time.

[0086] The supply of electrical energy to the motor can be diverse and varied. For example, the motor can be connected to batteries (lithium-ion, lead, etc.), or to any electrical network. Furthermore, the supply of energy directly to the motor 200 or to a battery can also be done by means of renewable energy, for example solar energy, wind energy, by the movement of waves or tides.

[0087] Figure 5 illustrates an embodiment of the energy supply by a solution for recovering energy generated by waves. In this embodiment a float 230 is connected to transmission arm 240 to a toothed wheel 250. The transmission arm 240 preferably has a length greater than the radius of the lateral surface of the support 300. The transmission arm carries a ratchet 260.

[0088] The pawl 260 is configured to allow rotation of the toothed wheel 250 in a first direction of rotation, and to prohibit rotation of the toothed wheel 250 in a second direction of rotation opposite to the first direction of rotation.

[0089] The toothed wheel 250 can be connected to the support 300 either directly to the frame 100, or through an energy recovery device in order to supply energy to the motor. In this embodiment, the float 230 follows the movement of the waves of the liquid 2 with a slight offset relative to the support 300. This difference in movement is transmitted by the transmission arm 240 to the toothed wheel 250 by lever effect and makes it possible to actuate the rotation of the toothed wheel 250. Depending on the length of the transmission arm 240 it is possible to vary the difference in movement of the float 230 relative to the support 300. This difference makes it possible to set the toothed wheel 250 in motion.

[0090] Thus, the longer the transmission arm 240 is, the smaller the difference in movement required between the float 230 and the support 300 to set the toothed wheel 250 in motion will be. In other words, a small swell will allow the toothed wheel 250 to be set in motion.

[0091] This embodiment uses the principles of recharging automatic watches comprising a mechanical motor.

[0092] In the case where the toothed wheel is carried by the frame and directly transmits its rotational movement to the support 300, then the entire wave energy recovery system can be considered as the motor 200.

[0093] Finally, it is possible to couple the power supplies of the motor 200. For example, a switch can allow the motor 200 to be powered either by a renewable energy source or by a battery in order to be able to adapt to different weather conditions. The surplus energy produced by the renewable energy source can be used to recharge the batteries. Sprinkler device 500

[0094] The system 1 may comprise at least one and preferably several devices for spraying a liquid. For example, in the embodiment shown in FIG. 4, spraying devices, preferably at least one per support 300, make it possible to guarantee the correct supply of liquid, in particular of a mixture of nutrients, and therefore the correct humidification of the second face 420 of the sheet 400. This supply of liquid and / or nutrients makes it possible to better control the characteristics necessary for the production of microalgae in the form of a biofilm.

[0095] The sprinkler device may be attached to the frame 100 or have its own structure.

[0096] The spraying device 500 is equipped with a pump for drawing the emitted liquid from a reserve. The reserve may be the liquid 2 in which the system 1 floats. The liquid 2

[0097] Liquid 2 is a liquid allowing the cultivation of microalgae in the form of a biofilm. Advantageously, liquid 2 is water which can be salty or fresh with or without additives such as nutrient inputs for example. Liquid 2 can be contained in a natural expanse such as a lake, a watercourse or even the sea.

[0098] The liquid 2 can also be contained in an artificial basin, that is to say in a human construction for example a masonry or wooden tank or any other materials. The creation of an artificial basin allows in particular a better control of the characteristics of the liquid 2 such as its hydrogen potential (pH), its temperature, or even its composition in nutrients and / or waste or even its level or the presence of bacteria in the liquid 2. The artificial basin is open in its upper part and exposed at least partially to at least one light source 3. Light source 3

[0099] The light source 3 may be a natural source such as the sun or artificial light providing in particular a supply of ultraviolet light necessary for the cultivation of microalgae.

[0100] When using a natural body of water, the light supply is provided mainly by the sun. However, the system may include an additional light source 3 in addition to the main light source 3, thus making it possible to increase the brightness or the ultraviolet supply when the climatic conditions are not optimal and / or to expose to light portions different from those exposed by the main light source 3. Some specific embodiments

[0101] Figure 1 illustrates an embodiment of the system 1. The system 1 floats in a liquid. The system 1 comprises a first and a second support 300 connected and positioned substantially horizontally and parallel to each other. The first and second supports 300 are connected to each other by the frame 100 via the lateral surfaces of the two supports 300. A motor 200 is arranged on the frame 100 for example at one end. The motor 200 is configured to rotate the first support 300. The frame 100 comprises between the two supports 300 several floats 320 and / or ballast 310. A sheet 400 extends between the two supports 300 and drives them at least partially. The sheet 400 is rotated around the two supports 300 by the rotation of the first support 300 so that the portions in the direct exposure zone 3a alternate their positions with the portions in the indirect exposure zone 3b.The 400 tablecloth is relatively taut between the first and . second supports 300. In this embodiment, portions of the sheet 400 are exposed to the open air and other portions of the sheet 400 are immersed in the liquid 2.

[0102] Figure 2 illustrates an embodiment identical to that illustrated in Figure 1 but in which the entire system 1 has zero buoyancy. The system 1 floats between two waters. Advantageously, the entire sheet 400 is submerged.

[0103] According to a possible embodiment of this, a second motor 200 drives the second support 300 in rotation.

[0104] Figure 3 shows an embodiment similar to the first two with the difference that the floating system 1 comprises four supports 300 and no float. The supports 300 integrate the float and / or ballast function. The sheet 400 comprises portions exposed to the open air and submerged portions. The sheet 400 is stretched between the two most extreme supports 300.

[0105] Figure 4 shows an embodiment with four supports 300 positioned substantially vertically and parallel to each other. The supports 300 comprise a submerged part and an emerged part respectively according to the buoyancy of the support 300. The supports are connected to each other by the frame 100. Sprinkler devices 500 make it possible to moisten the non-submerged parts of the supports 300. A sheet 400 surrounds each support 300. In this embodiment, ballasts (not shown in the figure) can be positioned on the submerged parts in order to stabilize the system 1.

[0106] Finally, Figure 6 shows an embodiment in which the system 1 comprises a single support 300 positioned substantially horizontally. The frame 100 is fixed to a solid surface and the support 300 floats. The support 300 is for example partially submerged (five centimeters). A single sheet 400 preferably completely surrounds the support 300. The motor makes it possible to rotate the support 300 so that the portions of the sheet 400 located in the open air and in the direct light exposure zone 3a alternate their positions with the portions of the sheet 400 located in the submerged part of the support 300 and / or in the indirect exposure zone 3b.

[0107] The invention is not limited to the embodiments previously described and extends to all the embodiments covered by the claims.

Claims

Claims

1. System (1) for the production of microalgae in the form of a biofilm comprising a frame (100), at least one support (300) and a sheet (400) intended to receive the biofilm and in which: • the frame (100) is configured to receive the at least one support (300), • the at least one support (300) is configured to have a rotational movement around an axis of rotation and to support and impart the rotational movement on the sheet (400); • the sheet (400) is configured to at least partially surround the at least one support (300), characterized in that at least one of the support (300) and the frame (100) is configured so that the system (1) has a non-negative buoyancy in a liquid (2).

2. System (1) according to claim 1 wherein the system is configured to be at least partially immersed in the liquid (2).

3. A system (1) according to any preceding claim wherein the system is configured to be fully submerged in the liquid (2) and have zero buoyancy.

4. System (1) according to one of the preceding claims in which the system (1) comprises a movement module configured to allow the system (1) to alternately take a position completely immersed in the liquid (2) and a partially immersed position.

5. System (1) according to one of the preceding claims in which the at least one support (300) is cylindrical and is preferably taken from a roll or a sausage.

6. System (1) according to any one of the preceding claims comprising a motor (200) configured to impart the rotational movement around an axis of rotation of the support (300)

7. System (1) according to any one of the preceding claims wherein the displacement module comprises at least one ballast (310) configured to vary and stabilize the buoyancy of the system (1) in the liquid (2).

8. System (1) according to the preceding claim in which the at least one ballast (310) is arranged in the at least one support (300).

9. System (1) according to any one of the preceding claims comprising several supports (300) configured to be driven by at least one motor (200).

10. System (1) according to any one of the preceding claims comprising several supports (300) configured to be driven by several motors (200).

11. System (1) according to any one of the preceding claims comprising several supports (300) and at least one sheet (400) and in which each of the supports (300) is configured to support and impart its movement on at least one sheet (400).

12. System (1) according to any one of the preceding claims comprising several supports (300) and a number of sheets (400) equal to the number of supports (300) in which each of the supports (300) is configured to support and print its movement on a single sheet (400).

13. System (1) according to any one of claims 1 to 8 wherein the system comprises a single support (300) and a single sheet (400).

14. System (1) according to any one of the preceding claims wherein the motor (200) is a power device configured to recover energy from the movement of waves on the surface of the liquid (2).

15. System (1) according to one of the preceding claims in which the at least one support (300) is inflatable.

16. System (1) according to any one of the preceding claims in which the axis of rotation of the at least one support (300) is horizontal.

17. System (1) according to any one of claims 1 to 15 in which the axis of rotation of the at least one support (300) is vertical.

Images