Reactor with optimized lighting

Abstract

The present invention relates to a reactor comprising a container (1) containing a mass to be treated and at least one lighting device (2a, 2b) intended to facilitate the treatment of said mass, characterized in that each lighting device (2a, 2b) comprises a light diffuser comprising at least one microetched plate (211) that is transparent to light radiation.

Description

[Technical Field]

[0001] The present invention relates to the general technical field of reactors with integrated lighting, in particular reactors for the cultivation of light-sensitive microorganisms.

[0002] The reactor may be a bioreactor, or it may be a chemical or physicochemical reactor. [Background technology]

[0003] In the present invention, the term bioreactor, or biological reactor, refers to a reactor in which biological phenomena such as the growth of pure or congregate cultures of microorganisms (in particular microalgae) take place in a wide variety of fields, such as the treatment of wastewater, the production of biomass containing biomolecules of interest (i.e., biomolecules whose valorization is known), etc. The term therefore particularly encompasses reactors called fermenters.

[0004] Bioreactors typically include: for the production of biomass, for the production of metabolites, or for biotransformation of molecules of interest, It comprises a (cylindrical or parallelepiped) vessel containing a culture medium for a biological species (yeast, bacteria, microscopic fungi, algae, animal or plant cells).

[0005] Various types of operating conditions are required for the growth of biological species in such bioreactors. In particular, light-delivered autotrophic (or photoautotrophic) growth (also called photosynthesis) or mixotrophic growth (with the combined input of a carbon source and light) regimes are known. It should also be noted that light can affect cellular metabolism by inducing or suppressing the production of certain compounds, independent of growth and photosynthesis. Therefore, the provision of light during cultivation can be useful even when microorganisms are heterotrophic.

[0006] In the following, particular focus will be placed on photobioreactors, i.e. bioreactors in which light is supplied (continuously, periodically or in pulsed form).

[0007] Photobioreactors have already been proposed in which light is supplied from inside the vessel. US3986297 proposes in particular a photobioreactor in which light is supplied by immersion of a lighting means (such as a xenon lamp) in the medium. The disadvantage of this solution is that the efficiency of the photobioreactor is inversely proportional to its size. Thus, the greater the size of the photobioreactor, the less efficient it becomes.

[0008] Photobioreactors have also been proposed in which light is supplied from outside the vessel. A particularly well-controlled configuration consists of providing the vessel with a window that allows the transmission of light (natural or artificial) generated outside the vessel. The disadvantage of such a configuration is that the window limits the illumination surface and absorbs or reflects a large portion of the photons emitted by the light source.

[0009] Regardless of whether light is supplied from inside or outside the vessel, the productivity of a photobioreactor (biomass production per unit volume) is directly related to its specific surface (ratio of illuminated surface to culture volume). Therefore, it is necessary for the bioreactor to have a large illuminated specific surface.

[0010] A disadvantage of current photobioreactors, whether flat or cylindrical, is that they occupy a large bed surface for acceptable productivity.

[0011] Furthermore, regardless of the light source chosen to illuminate the medium (neon, LED, natural light), the photon energy delivery is done in a very localized manner, so that: - Most of the photons emitted by the light source cannot be biologically consumed by the microorganisms due to energy overload. - the control of the dissipation of heat generated by the light source is imperfect; -Manufacturing large photobioreactors is complex and expensive.

[0012] An object of the present invention is to provide a photobioreactor that is economical in terms of both investment and operating costs and has a reduced footprint.

[0013] Another object of the present invention is to calculate the photon yield (μmol-ph-s) provided by an illuminated surface per unit of power (watt). -1 The goal is to provide large-capacity photobioreactors (vessels of 1000 liters or more) with optimized fermentation. Summary of the Invention

[0014] For the above purpose, the present invention provides: The squares to be processed, At least one lighting device intended to facilitate the processing of this mass; A reactor comprising a vessel containing Each lighting device is a light diffuser including at least one micro-etched plate that transmits optical radiation, the plate having opposing rear and front surfaces and at least two edges between the rear and front surfaces, each surface having an area greater than an area of ​​each edge, the rear surface including a plurality of micropatterns; a light source that generates optical radiation, the light source being positioned at at least one edge of the plate and directed such that the optical radiation that it generates propagates within the plate; The present invention proposes a reactor comprising:

[0015] This solution makes it possible to obtain photobioreactors with yields (on the one hand in terms of energy and on the other hand in terms of biomass production) that are superior to existing photobioreactors.

[0016] Indeed, the use of one (or more) microetched plates allows a homogeneous transmission of the light radiation generated by the light source: the photon energy is guided throughout the microetched plate and emerges therefrom over the entire front surface, which improves the ratio of the illumination surface to the irradiated volume, which is in direct contact with the medium.

[0017] Therefore, the present invention provides a ratio: micromoles (μmol) per unit volume - photons s -1 W -1 This allows for increased productivity, ensures a reduced environmental impact of the photobioreactor, and reduces the costs associated with its operation.

[0018] Preferred, non-limiting embodiments of the assembly according to the present invention are as follows: - each plate may be substantially flat and may have four edges, and each light source includes a plurality of light emitting diodes disposed on at least one of the smallest edges; - each plate may be cylindrical and may have two edges, and each light source includes a plurality of light emitting diodes arranged on at least one of the two edges; The diodes of the plurality of light-emitting diodes may be arranged at the edge of the plate, furthest from the bottom of the container; -Each diffuser has a rear surface facing each other. Opposite a pair of micro-etched plates adapted to Each light diffuser may further comprise at least one layer of material that reflects light radiation, each layer of reflective material reflecting the rear surface of the respective plate. It exists in a covered state There are; Each light diffuser further comprises at least one transmitting layer, each layer of transmitting material facing the front surface of the respective plate. It exists in a covered state There are; the reactor may comprise a plurality of light diffusers, two adjacent light diffusers being separated by a distance comprised between 2 and 10 centimeters, preferably a distance comprised between 4 and 8 centimeters, more preferably a distance substantially equal to 6 centimeters; The light source of each lighting device may be configured to generate continuous light radiation; the reactor may comprise a plurality of light diffusers, two adjacent light diffusers being separated by a distance comprised between 8 and 150 centimeters, preferably comprised between 10 and 50 centimeters, more preferably a distance substantially equal to 11 centimeters; the light source of each lighting device may be configured to generate discontinuous light radiation in the form of flashes, including alternating dark and illuminated phases at a frequency comprised between 10 and 50 kHz, for example; the container can have a volume of 100 m3, the area of ​​the surface covered by the plates of the light diffuser being comprised between 2000 and 3000 m2, preferably between 2250 and 2750 m2, preferably substantially equal to 2500 m2; -Lighting equipment a first group of lighting devices having a first height; a second group of lighting devices having a second height that is lower than the first height; and It consists of The lighting devices of the second group are arranged between two consecutive lighting devices of the first group; The reactor may further comprise an injection system comprising a plurality of diffusion units, each diffusion unit comprising: extending between two adjacent light diffusers; and At least two consecutive light diffusers are spaced apart from each other; -Each lighting device can be connected to an independent power supply module so that it can be individually removed from the reactor during operation.

[0019] Other advantages and features of the reactor according to the invention will become more apparent from the following description of some various embodiments, given as non-limiting examples, and from the accompanying drawings, in which: [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic perspective view of a first variant of a photobioreactor according to the present invention. [Figure 2] FIG. 1 is a schematic perspective view of a lighting device. [Figure 3] 1 is a schematic cross-sectional view of a first embodiment of a lighting device. [Figure 4] FIG. 10 is a schematic cross-sectional view of a second embodiment of the lighting device. [Figure 5] FIG. 1 is a schematic diagram of an experimental variation of a photobioreactor. [Figure 6] 6 is a curve showing the biomass production yield (as a function of various parameters) obtained from experimental variations of the photobioreactor shown in FIG. 5. [Figure 7] FIG. 10 is a partial cross-sectional view of a second photobioreactor variation. [Figure 8] 1 is a curve showing the maximum concentration of microalgae as a function of the distance between two adjacent lighting devices. [Figure 9] FIG. 1 is a block diagram illustrating the difference between continuous and discontinuous illumination. [Figure 10] 1 shows the maximum concentration curves of microalgae as a function of the distance between two adjacent lighting devices, one with continuous illumination and the other with discontinuous illumination. DETAILED DESCRIPTION OF THE INVENTION

[0021] Various examples of photobioreactors according to the present invention will now be described with reference to the drawings, in which like elements are identified by the same reference numerals.

[0022] 1.Overview Referring to FIG. 1, the bioreactor comprises: - a container 1 intended to receive the mass to be treated; a plurality of lighting devices 2a, 2b; - an injection system comprising a number of units 3 for diffusing carbon dioxide (CO2) in the form of bubbles or in the form of a fluid consisting of CO2 dissolved in an aqueous medium.

[0023] Each lighting device is intended to be integrated into a vessel for treating a medium contained therein. The lighting devices are intended to be completely immersed in the medium. In the following, the bioreactor will be described with reference to the treatment of a biomass formed from microorganisms, for example microalgae. However, it will be understood that the following description also applies to other types of reactors, such as chemical or physicochemical reactors.

[0024] As shown in Figure 1, the lighting devices 2a, 2b are positioned at a non-zero distance from the bottom of the vessel. The lighting devices 2a, 2b may be at different heights. In particular, the bioreactor may be - first height h a a first group 2a of lighting devices, - first height h a Lower secondary height h b and a second group 2b of lighting devices having , with the illuminators of the second group 2b being arranged between two consecutive illuminators of the first group 2a, which promotes mixing and homogenization of the mass to be treated.

[0025] To further enhance the mixing and homogenization of the mass to be treated, a diffuser unit 3 of the injection system can be periodically positioned downstream of each lighting device of the first group 2a (in reactors that do not have a diffuser unit 3 downstream of the lighting devices of the second group 2b). Thus, after circulating under the lighting devices of the first group 2a, the mass to be treated is drawn vertically toward the top of the vessel 1 (i.e., away from the bottom) by the CO2 bubbles (or fluid containing dissolved CO2) emitted by the diffuser unit 3. The mass to be treated passes over the lighting devices of the second group 2b and falls by gravity toward the bottom of the vessel. This results in a circulation of the mass to be treated through the vessel, improving the mixing and homogenization of the mass to be treated.

[0026] Alternatively, the lighting devices 2a, 2b of the bioreactor may all be of the same height, which simplifies the installation of the lighting devices by the operator. In this case, the diffusion units 3 are arranged every two lighting devices, such that two consecutive diffusion units 3 are separated by two adjacent lighting devices 2a, 2b.

[0027] 1.1 Container The container 1 is intended to contain the mass to be treated and comprises a bottom and at least one side wall.

[0028] In the embodiment shown in Figure 1, the container 1 is substantially parallelepipedal, consisting of a base, four side walls and an at least partially removable roof (or lid).

[0029] In other embodiments, the container 1 may be cylindrical, with a lower base forming the bottom, an upper base forming the lid, and a sidewall between the lower and upper bases.

[0030] The material making up the walls of the container 1 can be stainless steel or equivalent. Of course, other materials (Plexiglass®, polypropylene, concrete, etc.) can be chosen depending on the intended use. In any case, the container is preferably made of a material that is resistant to cleaning agents (bleach, peroxidase, etc.).

[0031] 1.2 Lighting equipment Referring to FIG. 2, each of the lighting devices 2a and 2b has: one (or more) light diffusers 21; one (or more) light sources 22.

[0032] The light source 22 allows for the generation of a light flux. The light diffuser 21 - guide the luminous flux generated by the light source, - making it possible to redistribute the light flux in a homogeneous manner towards the mass to be treated.

[0033] Advantageously, each light source 22 can be independently connected to a power supply module, said module enabling the supply of the power required to generate the luminous flux. The fact that each light source is independently connected to a power supply module allows the lighting devices 2 a, 2 b to be individually removed from the bioreactor while the bioreactor is in operation.

[0034] 1.2.1 Light diffuser The light diffuser 21 comprises one (or more) textured plates 211. Each plate 211 may be substantially flat and rectangular (as adapted for parallelepiped containers) or cylindrical (as adapted for cylindrical containers).

[0035] Each plate 211 has a rear surface 2113, a front surface 2114, and in the case of a rectangular plate 211, four lateral ridges (i.e. edges) 2111, or In the case of the cylindrical plate 211, it comprises two lateral ridges (ie edges) 2111.

[0036] Each lateral ridge 2111 may be polished, and at least one of the lateral ridges 2111 is intended to be in contact with the light source 22 to allow transmission of the light flux through the plate 211 .

[0037] The material of each plate 211 may be polymethyl methacrylate (PMMA) or any other transparent material known to those skilled in the art that allows the transmission of the light beam emitted by the light source 22 by total internal reflection at the front and rear surfaces, e.g. another transparent methacrylate resin, such as methyl methacrylate, ethyl ethacrylate, butyl methacrylate, propyl or isopropyl methacrylate, or - transparent resins of the polystyrene, polycarbonate or polyacrylate type, or - Glass / quartz glass, can be.

[0038] 1.2.1.1 Micropatterns 3, each plate 211 includes a plurality of micropatterns 2112 on its rear surface 2113. The micropatterns 2112 make it possible to intercept the rays 23 of the light beam circulating through the plate 211 and direct them towards the front surface 2114, facilitating their transmission out of the plate 211. More specifically, the rays 23 that impinge on each micropattern 2112 are redispersed. Each ray 23 is re-emitted at an angle such that it can leave the plate 211 through the front surface 2114, opposite the rear surface 2113 that includes the micropatterns 2112.

[0039] Each micropattern 2112 can consist of a point or ridge-like cavity having a shape selected from the group consisting of a cone, a (poly)pyramid, a rectangle, or any other shape known to a person skilled in the art, and each micropattern 2112 makes it possible to deflect the light beam radiation 23. In particular, in the example shown in Figure 3, the micropattern 2112 consists of fine grooves parallel to the lateral ridges 2111 in contact with the light source 22.

[0040] Of course, the micropattern 2112 can consist of polarizing elements other than cavities, e.g. - light-diffusing particles arranged in the material that makes up the plate 211, or - A surface texture component disposed on the rear surface 2113, which may consist of, for example, hemispherical structures appearing on the surface, ridges extending outward from the rear surface 2113, pyramidal structures appearing on the surface, or a combination comprising at least one of the foregoing structures.

[0041] The height of each micropattern 2112 (i.e., the dimension along the axis perpendicular to the rear surface) may be between 0.15 and 0.5 μm, and the pitch between two adjacent micropatterns may be between 20 and 900 μm, and in particular may be 100 μm or more.

[0042] Advantageously, the micropatterns 2112 can be arranged on the rear face 2113 according to a continuous distance inversely proportional to the distance of the micropattern 2112 from the lateral ridge 2111 in contact with the light source 22. Such an arrangement makes it possible to obtain a constant light intensity over the entire surface of the rear face 2113. In fact, the intensity of the light beam transmitted through the plate 211 decreases depending on the distance to the light source 22. By varying the density of the micropatterns 2112 on the rear face 2113, it is possible to compensate for the loss of intensity due to an increase in the density of the micropatterns 2112.

[0043] 1.2.1.2 Reflective layer The light diffuser 21 may comprise a layer 212 of material that reflects light flux.

[0044] The layer of reflective material 212 preferably includes a rear surface 2113 of the plate 211 that includes a plurality of micropatterns 2112. It exists in a covered state do.

[0045] The layer of reflective material 212 may be comprised of a film of reflective material, such as a metallized aluminum film, or alternatively, the layer of reflective material 212 may be comprised of paint made of a material having a lower refractive index than the refractive index of the material 211 comprising each plate 21.

[0046] 1.2.1.3 Transmission Layer The light diffuser 21 may comprise a transmitting layer 213 on the front surface 2114 of the plate 211 .

[0047] The transmission layer 213 makes it possible to facilitate the transmission of the luminous flux radiation 23 towards the outside of the plate 211 .

[0048] The transmission layer 213 also makes it possible to smooth the lighting effect obtained by the light diffuser 21 .

[0049] The transmission layer 213 further makes it possible to protect the plate 21 from possible mechanical shocks (such as scratches due to friction).

[0050] The transmission layer 213 may, for example, consist of a protective varnish having a refractive index close to that of the material from which the plate 211 is made.

[0051] 1.2.2 Light source Each light source 22 may comprise one (or more) light emitting diodes (LEDs) 221. Preferably, each diode 221 is a high-power light emitting diode (HPLED), i.e., an LED with a power greater than 1 watt. For example, each diode 221 may be a light emitting diode mounted directly on a chip (also known as a "COB" LED, an acronym for "chip-on-board"). In this case, the light source 22 may comprise (for example) a COB LED module consisting of multiple LED chips fixed to a ceramic substrate. This allows for the generation of a more powerful and denser luminous flux.

[0052] The diodes 221 of the light source 22 may be individual or may be arranged in a "strip" or "ribbon" configuration (see patent application FR1050015). Using diodes arranged in a ribbon configuration facilitates the manufacture of the lighting device, and it is intended that each light source 22 contacts a lateral ridge 2111 of the plate 211 of the light diffuser 21. The diodes 221 may be supplied with electrical energy via one or more connecting cables electrically connected to an electrical energy source.

[0053] Regardless of the arrangement chosen, the diodes 221 of the light source 22 may all be identical with the same excitation scheme or may be different. In particular, the diodes 221 of the light source 22 may be: - distinct excitation methods (e.g., some continuous, others flash at frequencies between 1 and 150 kHz), and / or - They can have distinct emission spectra (e.g., some white light and others blue light), etc.

[0054] Each light source 22 may include one or more reflectors (not shown) that reflect, redirect, and concentrate the light generated by the diodes 221 .

[0055] Each light source is intended to be in contact with a lateral ridge of the plate 211 so that the luminous flux radiation 23 generated by the light source propagates inside the plate 211. Advantageously, the diodes 221 and the connecting cables are embedded / cast in resin to seal each light source.

[0056] 3, the lighting devices comprise light sources 22 intended to be in contact with the lateral ridges 2111 of the plate 211. Alternatively, each lighting device may comprise two light sources 22 intended to be in contact with respective opposite lateral ridges 2111 of the plate 211. Further alternatively, each lighting device may comprise four light sources 22 intended to be in contact with respective lateral ridges 2111 of the plate 211.

[0057] 1.3 Injection System The injection system supplies nutrients, especially CO2, to the bioreactor. In particular, the injection system: - provide the carbon dioxide necessary for the development of biomass, and - making it possible to suspend the carrier particles of the microorganisms contained in the biomass medium.

[0058] The supply of carbon dioxide can be continuous or discontinuous in response to certain criteria such as time or pH. As mentioned earlier, carbon dioxide can: - in the form of bubbles, or - in the form of an aqueous solution that is pumped or forced into the bioreactor.

[0059] The introduction of carbon dioxide in the form of bubbles allows for better dispersion of the CO2 within the container.

[0060] The injection system may include: a CO2 supply unit, such as a booster (in the case of gaseous CO2) or a pump (of the turbine type in the case of fluid CO2), preferably with a check valve to avoid the rise of sludge or waste liquid in the CO2 supply unit, - a number of broadcast units 3 forming: For gaseous CO2, a micro-bubbling head for dispersing bubbles of different diameters; In the case of CO2 dissolved in an aqueous medium, a fluid injection nozzle to disperse the fluid containing the dissolved CO2.

[0061] The diffusion unit can be of different types known to those skilled in the art, such as a diffuser made of a microporous composite material, a diffuser with a membrane (EPDM, silicone, etc., preferably EPDM), a diffuser made of ceramic, or a slotted diffuser.

[0062] Each diffusion unit 3 is preferably located immediately adjacent to the bottom of the container. Furthermore, each diffusion unit 3 is located between two adjacent lighting devices 2a, 2b, and different diffusion units 3 are arranged such that each diffusion unit 3 is surrounded by a lighting device 2a, 2b that is different from the lighting devices 2a, 2b that surround the other diffusion units 3. In other words, each diffusion unit 3 is separated from the nearest diffusion unit 3 (or nearest units) by two lighting devices 2a, 2b.

[0063] 1.4 Biomass Processing The biomass cultivated in the reactor according to the invention can be harvested by techniques known to those skilled in the art, such as sedimentation, filtration, flotation or centrifugation techniques.

[0064] The harvesting of the biomass can be carried out continuously or semi-continuously, especially if the bioreactor is installed on an industrial site. For this purpose, the bioreactor can be associated with a separation unit (such as a decanter and / or a centrifuge and / or a filter) that allows to take a portion of the contents of the vessel and separate the biomass from the culture medium.

[0065] The biomass thus extracted is packaged (vacuum frozen or otherwise) for further use. The medium, once separated from the biomass, can be reintroduced into the bioreactor vessel.

[0066] 1.5 Other features of bioreactors The reactor may also comprise a control module including one or more sensors for checking the parameters of the bioreactor. In particular, the control module may comprise: - one (or more) pH probes, - one (or more) sensors for measuring CO2 levels, - one (or more) light sensors; - One (or more) POs 3 / 4, and / or NO3 and / or NH4 sensors, - One (or more) temperature sensors.

[0067] The various sensors and probes of the control module make it possible to maintain optimal values ​​of the bioreactor parameters that affect the growth of the biomass.

[0068] In particular, the control module can adjust the amount of CO2 injected into the culture medium in response to measurements such as those determined by a pH probe and / or a sensor measuring CO2 levels. For example, if the measured CO2 level is below a threshold, the control module can command a greater amount of CO2 (relative to the target amount) to be injected into the vessel. Conversely, if the measured pH is below a predetermined threshold, the control module can control the injection of a lesser amount of CO2 (relative to the target amount).

[0069] Similarly, if the measured temperature is lower (or higher) than a threshold temperature, the control module can control activation of a heat exchanger, such as a plate heat exchanger integrated into the bioreactor vessel, to heat (or cool) the medium.

[0070] Also, P.O. 3 / 4 Depending on the measurements taken by the NO3 and NH4 sensors, the control module can adjust the amount of nutrients (phosphorus, nitrogen, etc.) injected into the culture medium (by activating / deactivating pumps, etc. connected to the nutrient sources).

[0071] Furthermore, measuring the information representing the light intensity in the medium allows for estimation of the biomass concentration in the vessel. Therefore, the biomass harvesting process can be adjusted. In particular, if the light measurements in the vessel indicate that the biomass concentration is too low, the control module can pause biomass harvesting. Conversely, if the light measurements in the vessel indicate that the biomass concentration is too high, the control module can initiate biomass harvesting.

[0072] 2. Characteristics of the photobioreactor 2.1 Continuous light radiation Various aspects are described regarding the dimensions of the bioreactor that allow optimal use of the light flux coming from the lighting device. The dimensioning of the bioreactor is done by considering a continuous light supply, i.e., by considering that each light source 22 produces continuous light radiation of constant intensity over time.

[0073] 2.1.1 Photon trapping model In order to understand whether the photon flux from the lighting device is optimally used by the mass being treated, it is proposed to use a model of photon capture by microalgae according to the radiating surface (area) and the surface geometry of the reactor.

[0074] The following description shows adjustable parameters for estimating the productivity of a photobioreactor. Here, it would be preferable to reduce the unilluminated parts of the reactor as much as possible and increase the surface area that receives the photon flux.

[0075] The global model for the surface yield of the photobioreactor is as follows:

number

[0076] The maximum performance of a photobioreactor can be characterized by some simplifying ideal-case constants. Thus, production depends on the following factors: - Unilluminated volume ratio (f d =0) corresponding to the dark area “Sx”:

number

number

number

[0077] The above calculation rules are as follows: - 0.2m wide, 0.4m long acrylic sheet -250 μmol / m2 / s incident light, - Total reactor volume 0.008m 3 , -No shadow zone (fd=0), By applying the above, the maximum theoretical volumetric productivity is estimated to be 100 mg / L / d, as shown in the table below.

[0078] [Table 1]

[0079] This is confirmed during experiments using the reactor shown in Figure 5, where the lighting device comprises an acrylic plate placed under the bottom of the vessel with transparent walls. As shown in Figure 6, the average production is 102 mg / L / d over 140 hours (min: 60 mg / L / d, max: 130 mg / L / d).

[0080] The addition of air containing 2% CO2 ensures mixing and provides carbon to the mass being processed.

[0081] 2.1.2 Determining the Optimal Plate Surface Area for Reactor Illumination The objective is to determine the optimum surface area for diffusing the light flux for the reactor. Of course, the number and placement of the lighting devices can vary depending on the amount of biomass to be produced.

[0082] Applying the global modeling formula described in 2.1 above, 100m 3 1 ml of culture in a volume of 3 If you want to produce 1 kg of biomass per unit of light, the lighting system will need to emit 1000 μmol / m 2 / s (light source) emitting 2500m 2 The lamp must be equipped with a luminous plate (light diffuser).

[0083] This number is directly related to the desired yield, volume, (surface) shape, and light intensity.

[0084] The following table was obtained: [Table 2]

[0085] 2.1.3 Determining the maximum amount of biomass that should not be exceeded The goal is to avoid dark zones within the medium (i.e., f d The goal is to determine the maximum concentration that should not be exceeded (to maintain σ = 0). Consider a reactor as shown in Figure 7. This reactor comprises: - A container with the following dimensions: 17 meters x 2 meters x 3 meters (length x width x height; meters), with a volume of 100 m 3 - A lighting device comprising a plate with dimensions 3 meters x 2 meters x 0.01 meters (length x width x thickness).

[0086] 2500m 2 To have a luminous surface (area) of 1, the number of plates is 2500 / (3 x 2) = 417 plates, for a total thickness of 4.17 meters (each plate is 1 cm thick).

[0087] To minimize the space requirements associated with the introduction of the plates into the container, each lighting device can include two plates joined by their rear faces with their front faces facing each other (the rear faces of the two plates extend opposite and touch each other). An example of such a lighting device is shown in Figure 4. The distance between the different lighting devices is given by the following formula:

number

[0088] The table below summarizes the different results described above.

[0089] [Table 3]

[0090] [Table 4]

[0091] Avoid having dark zones in the middle (i.e., f d = 0), sufficient photon flux (F) is required up to the intermediate zone (B) between two adjacent illuminators.

[0092] The luminous intensity as a function of distance Z can be expressed using the following formula:

number

[0093] Figure 8 shows the maximum concentration of microalgae as a function of the distance between two adjacent lighting devices. 2 From this it is possible to determine not to exceed the maximum concentration if it is deemed that the amount of light is insufficient to obtain a sufficient yield.

[0094] For the device shown in Figure 7 with intermediate zone B located 0.03 meters from each lighting device (and taking into account that there is 6 centimeters of free space between the lighting devices), the maximum concentration that should not be exceeded is 1.5 g / L.

[0095] This concentration can be measured using a suspended solids sensor such as the 6131 Blue-Green Algae Sensor or the ALS-OD4.

[0096] 2.1.4 CO 2 Determining the quantity The amount of CO2 provided must correspond to the rate of photons provided (provide the same amount of CO2 as the photons provided by the reactor).

[0097] Therefore, the flow rate of the mixture (air / CO2) must be adjusted to the selected light.

[0098] 1kg / m 3 For / d, 4.77m 3 / h flow rate of 90% CO2 is required.

[0099] [Table 5]

[0100] 2.1.5 Plate characteristics Those skilled in the art will understand how to select the type of light for each light diffuser, giving priority to the following: - type of etching that allows the photons to be optimally transmitted throughout the plate (type V...), - material with optimal optical transmission for the transmission panel to be etched (acrylic, polycarbonate, ...), - Optimal reflective materials for maximum light intensity, - The most effective material for homogenizing the photon flux.

[0101] A skilled artisan will select the placement of LEDs on one, two, three, or four sides of each plate, as well as the shape of each plate (rectangular, square, cylindrical) according to the culture conditions. A skilled artisan will prefer the most uniform LED placement, to fill the entire edge of the etched plate.

[0102] 2.2 Discontinuous light emission Various aspects regarding the dimensions of the bioreactor are described taking into account discontinuous light supply, i.e., each light source 22 generates discontinuous light emissions (flashes) constituted by closely alternating dark and light phases (for example, at a frequency comprised between 10 and 50 kHz).

[0103] By way of example, FIG. 9 shows the difference between discontinuous illumination 31 and continuous illumination 32.

[0104] Such a discontinuous light supply has a positive effect on the culture yield in terms of biomass. As will be shown below, the transition from a continuous to a discontinuous light supply makes it possible to increase the distance between two adjacent light diffusers 21 (included between 2 and 10 centimeters, preferably between 4 and 8 centimeters, more preferably substantially equal to 6 centimeters), while keeping the other parameters the same as those calculated previously.

[0105] 2.2.1 Calculating the optimal distance between adjacent lighting fixtures The continuous average intensity at the light diffuser 21 is 1000 μmol.m -2 .s -1 Consider a system where

[0106] 1000 μmol.m -2 .s -1 Parameterizing this average (continuous) intensity in terms of "flashes" while maintaining an average irradiance of 10000 μmol.m -2 .s -1 You can get a flash wave of: - Cycle time t cycle becomes: t cycle =t light + t dark (s) or frequency (Hz) where t light corresponds to the illumination phase, and t dark corresponds to the dark phase; - The irradiated area Φ is: Φ=(t light / (t light +t dark )) - Integrated Radiation: I m =I f Φ where: Φ=10%; I m = 1000 μmol.m -2 .s -1 I m =If ·Φμmol.m -2 .s -1 I f = 10000 μmol.m -2 .s -1

[0107] This photon wave makes it possible to increase the penetration distance of the photons into the medium, and therefore to increase the distance between light diffusers 21 within the same biomass concentration.

[0108] As shown in Figure 10, which shows the microalgae concentration curves 33, 34 as a function of the distance between two adjacent lighting devices: - on the one hand in the case of continuous illumination (curve labeled 33), and - On the other hand, in the case of discontinuous illumination (curve labeled 34), The intermediate distance can be extended to 0.055 meters in flash at a concentration of 1.5 g / L. In other words, the lighting device can be positioned such that the distance between two adjacent light diffusers 21 is substantially equal to 11 centimeters.

[0109] 3. Other Embodiments In the above description, various variants of bioreactors have been described, in particular bioreactors intended for industrial use, which allow for the treatment of released gases. Of course, the scope of the invention is not limited to large bioreactors intended for industrial use.

[0110] In particular, in alternative embodiments, the bioreactor may be of smaller dimensions. For example, the bioreactor may comprise: - have transparent or translucent walls, Length ranges from 1 to 10 meters. width between 50 centimeters and 5 meters, Containers with a thickness between 4 and 30 centimeters; - a single lighting device integrated with the container; - An injection system containing one (or more) diffusion units.

[0111] Such bioreactors can be used in particular in urban applications to replace certain existing panels, such as one (or more) walls of an Abribus® or any bus shelter type.

[0112] Of course, the shape of the container is not necessarily parallelepiped, but may vary depending on the intended use (e.g., cylindrical).Similarly, depending on the use, the walls of the container may not be transparent or translucent.

[0113] In all cases, the lighting device preferably: - parallel to the side wall of the large container (including a light diffuser consisting of a pair of plates), and - equidistant from the side wall having the larger dimension The nozzle is disposed in the container so as to extend in the direction of the arrow.

[0114] Such an illumination device comprises a light diffuser preferably consisting of a pair of micro-etched plates joined at their rear surfaces, said plates having substantially the same shape and dimensions as the larger sidewall of the container (plate dimensions = 90-100% of the larger sidewall dimensions), and the illumination device also comprises a light source as described above.

[0115] Preferably, the dimensions of the container are adapted to optimize the illumination of the mass to be treated by the illumination device. - Light diffuser and - each larger side wall of the container; The distance separating them may be comprised between 1 and 15 centimeters, preferably between 2 and 10 centimeters, and even more preferably between 3 and 6 centimeters.

[0116] 4. Conclusion The above-mentioned solution makes it possible to increase the energy and biomass production of the reactor, in particular thanks to the uniform transmission of light and the optimal dimensioning of the various components of the reactor according to the maximum amount of biomass desired in the reactor.

[0117] This is valid for mixotrophic cultures, autotrophy of photosynthetic organisms, as well as for primarily heterotrophic mixotrophic cultures where light is not important for photosynthetic activity, except in the case of the induction of molecules of interest such as pigments and / or oils (WO2017050917).

[0118] The invention shown above has many applications, for example it can be used to create a carbon sink that makes it possible to reduce the amount of carbon dioxide in the atmosphere by absorbing carbon (carbon monoxide / carbon dioxide) contained in the atmosphere.

[0119] The reader will appreciate that many modifications can be made to the invention described above without substantially departing from the novel teachings and advantages set forth herein.

[0120] For example, in the preceding description, the lighting and heating devices were incorporated into a reactor that included a rotating assembly intended to ensure mixing of the microbial mass. It will be apparent to those skilled in the art that the lighting and heating devices described above can be incorporated into a reactor without a rotating assembly.

[0121] Accordingly, all such modifications are intended to be included within the scope of the appended claims.

Claims

1. The square to be processed, at least one lighting device (2a, 2b) intended to facilitate the processing of said mass; A reactor comprising a vessel (1) containing Each lighting device (2a, 2b) a light diffuser (21), the light diffuser (21) comprising at least one micro-etched plate (211) that is transparent to light radiation (23), the plate (211) having opposite rear and front faces (2113, 2114) and at least two edges (2111) between the rear and front faces (2113, 2114), the area of ​​each face being greater than the area of ​​each edge, the rear face (2113) comprising a plurality of micropatterns (2112); a light source (22) that generates optical radiation (23), the light source (22) being arranged at at least one edge of the plate (211), the optical radiation (23) that it generates being directed to propagate within the plate (211); Equipped with A reactor characterized in that each light diffuser (21) further comprises at least one transmitting layer (213), each layer (213) of transmitting material being present over the front surface (2114) of the respective plate (211).

2. 2. The reactor of claim 1, wherein each plate (211) is substantially flat and has four edges (2111), and each light source (22) includes a plurality of light-emitting diodes disposed on at least one of the smallest edges.

3. 2. The reactor of claim 1, wherein each plate (211) is cylindrical and has two edges, and each light source (22) includes a plurality of light-emitting diodes arranged on at least one of the two edges.

4. 4. The reactor according to claim 2 or 3, wherein the diodes of the plurality of light-emitting diodes are arranged at the edge of the plate (211) that is furthest from the bottom of the vessel (1).

5. A reactor according to any one of claims 1 to 4, wherein each light diffuser (21) comprises a pair of micro-etched plates (211) with their rear faces (2113) facing each other.

6. 6. The reactor of claim 1, wherein each light diffuser (21) further comprises at least one layer (212) of material that reflects the light radiation (23), each layer (212) of reflective material being present over the rear face (2113) of the respective plate (211).

7. A reactor according to any one of claims 1 to 6, comprising a plurality of light diffusers (21), wherein two adjacent light diffusers (21) are separated by a distance comprised between 2 and 10 centimetres.

8. Reactor according to any one of the preceding claims, wherein the light source (22) of each lighting device (2a, 2b) is configured to generate continuous light radiation.

9. A reactor according to any one of claims 1 to 6, comprising a plurality of light diffusers (21), two adjacent light diffusers (21) being separated by a distance comprised between 8 and 150 centimetres.

10. 10. The reactor according to claim 9, wherein the light source (22) of each lighting device (2a, 2b) is configured to generate discontinuous light radiation in the form of flashes, comprising alternating dark and illumination phases.

11. The container is 100 m ３ and the area of ​​the surface covered by the plates of the light diffuser (21) is between 2000 and 3000 m ２ The reactor according to any one of claims 1 to 10, which is comprised between

12. The lighting device comprises: First height (h ａ a first group of lighting devices (2a) having The first height (h ａ ) lower than the second height (h ｂ a second group of lighting devices (2b) having Reactor according to any one of claims 1 to 11, wherein a lighting device of the second group is arranged between two consecutive lighting devices of the first group.

13. 13. The reactor according to any one of claims 1 to 12, further comprising an injection system comprising a plurality of diffusion units (3), each diffusion unit (3) extending between two adjacent light diffusers (21) and spaced apart from other diffusion units (3) by at least two consecutive light diffusers (21).

14. Reactor according to any one of the preceding claims, wherein each lighting device (2a, 2b) is independently connected to a power supply module so that it can be individually removed from the reactor during operation.

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