Light panel, plate photobioreactor and photobioreactor system for biomass production

Abstract

The subject of the invention is a light panel containing at least two projections connected to the side edges of the light panel, wherein a light source is attached to at least two projections, and the light panel and projections are made of a substantially transparent material that allows light to be introduced, scattered or distributed. Another subject of the invention is a plate photobioreactor comprising a housing connected to a housing base and at least one light panel according to the present invention. Another subject of the invention is a biomass production system comprising at least two interconnected photobioreactors according to the invention.

Description

[0001] Light panel, plate photobioreactor and photobioreactor system for biomass production

[0002] The invention concerns a light panel, a plate photobioreactor and a photobioreactor system for biomass production involving carbon dioxide sequestration by photosynthetic organisms. The invention is used in the production of biological biomass for the generation of renewable energy, fertilisers, feed additives, bioplastics, cosmetics, pharmaceuticals, textiles, biofuels and other applications, as well as in carbon dioxide sequestration.

[0003] A flat photobioreactor (PBR) is known from the literature publication by Y. Sun et al., which reduces the adverse effect of light attenuation on microalgae growth, where hollow polymethyl methacrylate (PMMA) tubes are placed in the flat photobioreactor (PBR) as light guides. In this way, part of the incident light could be transmitted and emitted into the interior of the PBR, providing a secondary light source for cells in light-deficient regions. The average light intensity in the inner regions was increased 2-6.5 times after 3.5 days of cultivation, resulting in an increase in biomass production of approximately 23-24% compared to cultivation in a PBR without PMMA tubes. The photosynthetic efficiency of microalgae in the proposed PBR increased to approximately 12.5%. In addition, the installation of empty PMMA tubes caused turbulent flow in the microalgae suspension, which promoted mixing of the microalgae suspension. However, the increased biomass production was mainly attributed to the optimised light distribution in the PBR [1],

[0004] US patent application US20160113224 Al discloses a photobioreactor system designed for optimal algae productivity at high volumes to ensure high yield. The photobioreactor system comprises photobioreactor units that can be isolated from each other to reduce culture collisions; a series of dispersed acrylic rods attached to the bottom of a removable circular acrylic top in each photobioreactor unit, which provide more light to the photobioreactors; a dual parabolic trough mirror system that uses two parabolic trough mirrors to reflect and concentrate sunlight into fibre optic cables; and an algae cycle system mounted at the bottom of each photobioreactor unit and driven by air to circulate the algae suspension in a vertical motion. A solution for large-scale algae cultivation. The system uses mirrors to collect sunlight and track the movement of the sun.

[0005] Polish patent description PL242154 Bl describes a system for cultivating photosynthetic microorganisms, which consists of a photobioreactor, a suction-pressure pump, a quantum immersion sensor for measuring the intensity of photosynthetically active radiation (PAR), a temperature sensor, a CO2 and introducing other process gases, a biomass collection system, a UV filter measurement and disinfection unit, a system for replenishing the medium and inoculating the inoculum, and a heatingcooling system. The photobioreactor is a cylindrical glass reaction vessel with a height-to-diameter ratio of 0.2 to 0.3, transparent in the visible spectrum and invisible to photosynthetically activeradiation (PAR), embedded inside a cylindrical light jacket, and the tank also has a bottom light panel and a top light panel.

[0006] Polish patent description PL229874 Bl describes a photobioreactor for CO2biosecquestration, containing algae or cyanobacteria biomass immobilised in capsules with an outer shell. Light is supplied to the capsules from a light source via a separate single light conduit. In the photobioreactor, the capsules are surrounded by a gaseous atmosphere and are moistened with a culture medium and periodically rinsed. The photobioreactor has a multi-sided or circular cross-section.

[0007] The American patent application US20090230040 Al describes a sewage treatment plant that reduces greenhouse gas emissions, captures CO2and enables biomass production. The device comprises a series of rotating wheels with media that enable optimal mixing of algae to ensure balanced growth. The wheel, half submerged in the sewage stream, is rotated by compressed air, which introduces more carbon dioxide into the sewage. This accelerates the growth of algae attached to the filling. Solar energy is also important. Sunlight falling on the tank with the filling and algae on its surface contributes to the process of photosynthesis.

[0008] A reactor containing a glass chamber consisting of a glass plate and attached discs of algal biofilm, which were placed on a frame at a certain angle of inclination to the horizontal plane, is known from the literature publication by P. Cheng et al. The medium was driven by a peristaltic pump to facilitate circulation of the medium within the system. Cold white fluorescent lamps provided illumination inside the chamber where the algae cells were grown. [2]

[0009] A two-region photobioreactor is known from the literature publication by Suh LS. et al. for simplifying the commercial two-step astaxanthin production process through the cultivation of Haematococcus pluvialis. Thanks to the reactor, high biomass yield is achieved in the inner core region and simultaneous accumulation of astaxanthin in the outer mantle region. The air-lift photobioreactor is a cylindrical photobioreactor consisting of two concentric cylindrical tubes made of Pyrex glass. Their lower parts have been modified into a cone shape to reduce cell sedimentation. The outer tube has two necks, and both necks have a silicone stopper with four holes for inoculation, fresh medium inlet, gas outlet and sampling. The cells in both regions were mixed by the movement of rising gases, which were introduced through the gas inlet hole at the end of the respective conical mantle. Fluorescent lamps are used for illumination, which are mounted on a frame and positioned symmetrically at the same distance from each other. [3]

[0010] A bioreactor with vertically positioned filling, which is placed in a plexiglass housing, is known from the literature publication by M. Osorio et al. Cotton fabric was tested as a material for creating an algal biofilm. The authors chose this substrate because of the promising results obtained in other tests. Furthermore, as demonstrated in previous studies, this material has other advantages, such as local availability, low cost, reusability and easy production. The vertical position of the carrier allowedfor its uniform illumination and the flow of synthetic wastewater over the biofilm. The medium flows in a thin layer over the biofilm and then falls to the bottom of the reactor, where it collects in a collection trough that directs the medium to the outlet opening and then to the medium collection vessel. [4]

[0011] A photobioreactor with a glass plate placed vertically in the centre of a glass chamber is known from the publication by T. Liu et al. One surface of the plate, which is illuminated, is covered with a layer of filter paper. Algae cells were evenly filtered on a cellulose acetate / nitrate membrane to form an algae "disc". The algae "disc" was then placed on filter paper. During cultivation, the medium was dripped into the space between the filter paper and the glass plate from a perforated nylon tube, which was placed on the upper edge of the glass plate so that the filter paper, cellulose membranes, and algae "discs" were kept moist during the soaking of the culture medium. The flow rate of the culture medium is controlled to maintain good adhesion of the algae cells with minimal flushing. [5] A bioreactor with attached biomass, whose main element is vertically positioned plates as filling, is known from the publication by M. Krzemieniewski. Plastic plates measuring 80x150 mm were used. The spacing between the plates was 7 mm. They were placed in four plastic containers, each with a capacity of 2.4 litres. Above the upper edges of each filling, there was a perforated plate that allowed the medium to be evenly distributed over the upper edges of the plates. The containers were stacked one above the other, and above the last one, there was a 2.4-litre tank, which served as an expansion chamber for the dosed medium. A pipe for the discharge of purified gases was also installed in its upper part, and in the lower part there were two pipes connected to the last upper reactor, through which both the purified gases and the nutrient solution flowed. The fillings were illuminated by two fluorescent lamps, which emitted essentially white light with a colour temperature of 6500 K. The power of both fluorescent lamps was 36W. The gas was supplied by a diaphragm pump and introduced into the last lower container with filling, which was also connected to a 500 ml settling tank. In the settling tank, the washed-out biomass of algae and cyanobacteria separated from the medium and was gradually removed. From the settling tank, the clarified medium flowed into a 15-litre plastic tank with a medium, in which a submersible pump for dosing the medium was installed, which switched on cyclically every 5 minutes and operated for 15 seconds. [6]

[0012] Anthropogenic carbon dioxide emissions contribute significantly to global warming and adverse weather conditions. Excess co2that is not balanced accumulates in the atmosphere, causing an increase in air temperature. For this reason, many countries have adopted long-term programmes in their economic plans that aim to significantly reduce co2emissions into the atmosphere. To achieve this, new techniques are being sought to remove CO2from exhaust gases and waste gases from various industrial sectors. One such alternative solution, based on the mechanism of converting CO2into a form of biomass, is biological sequestration by photosynthetic organisms in photobioreactors. Theproblem is achieving high efficiency in the co2biosequestration process, which mainly depends on the type of photobioreactor and specific process parameters, but also on the media used, the temperature range of the process, and the source and wavelength of light. The selection of light intensity and exposure times is crucial in the biomass production process, but often creates many technological problems, namely uneven light supply, point accumulation of light flux, excessive light intensity, uneven-concentric light emission, which negatively affects the development of photosynthetic organisms and, as a result, reduces biomass production efficiency or completely inhibits it.

[0013] The technical problems that occur in the current state of the art of photobioreactor use also concern the construction of the devices, operational problems, as well as investment and operating costs. The purchase and maintenance of photobioreactors is costly, mainly due to advanced technologies, unusual facility designs and the need to maintain appropriate conditions inside the reactor. Photobioreactors require advanced monitoring and automation systems, which can cause technical problems and require specialist knowledge to operate. In closed reactors, where it is difficult to remove excess microalgae and cyanobacteria biomass, problems arise with the supply of adequate light and nutrients. Another significant problem is the scalability of photobioreactors, which is limited due to the increasing costs and technical challenges associated with a large number of devices. However, as already mentioned, the most important problem with this type of bioreactor is how to provide sufficient light. Furthermore, the use of conventional methods of biomass production and co2sequestration simultaneously increases energy costs and affects the carbon footprint of the entire process. In order for photobioreactors to become more popular and widely available, new designs are needed to significantly reduce the cost of providing light for microalgae, cyanobacteria or photosynthetic bacteria.

[0014] The aim of the invention was to develop a light panel design and a panel photobioreactor containing a light panel that would enable increased and accelerated algae growth on the light panel and ensure even distribution of light flux in the panel, enabling photosynthetic microorganisms to be illuminated from the inside and outside of the biofilm, biofilm. Another objective was to develop a light plate and a photobioreactor in which the light plate with algae, cyanobacteria or photosynthetic bacteria attached to its surface is located above the surface of the culture medium or fully immersed in the culture medium.

[0015] Unexpectedly, all of the above-mentioned technical problems have been solved thanks to this invention.

[0016] The subject of the invention is a light panel, characterised in that it contains at least two projections connected to the side edges of the light panel, with a light source attached to at least two projections, while the light panel and projections are made of a material that allows light to be introduced, scattered or distributed.Advantageously, the panel is characterised in that the material enabling the introduction, scattering or distribution of light is a substantially transparent material.

[0017] Advantageously, the plate is characterised in that the essentially transparent material is an essentially transparent polymeric material or an essentially transparent inorganic material.

[0018] Advantageously, the plate is characterised in that the essentially transparent polymeric or inorganic material has a refractive index in the range of 1.30 to 1.95, advantageously 1.30 to 1.70, preferably 1.30-1.50, most preferably 1.30-1.40, at a wavelength in the range of 400-700 nm.

[0019] Preferably, the plate is characterised in that the essentially transparent polymeric or inorganic material has a transmittance in the range of 80-100%, preferably 85-100%, more preferably 90-100%, most preferably 95-100% at a wavelength in the range of 400-700 nm.

[0020] Advantageously, the plate is characterised in that the essentially transparent polymeric material is selected from the group comprising: polymethyl methacrylate, polyethylene, polypropylene, polyethylene terephthalate, polycarbonate.

[0021] Advantageously, the plate is characterised in that the essentially transparent inorganic material is selected from the group comprising: aluminosilicate glass, borosilicate glass, optical glass, optical glass fibre.

[0022] Advantageously, the panel is characterised in that it contains at least one additional protrusion connected to the flat part of the light panel.

[0023] Advantageously, the plate is characterised in that it contains four projections, two of which are connected to the side edges of the light plate, and the other two are connected to the flat part of the light plate.

[0024] Advantageously, the panel is characterised in that the projections are covered with a reflective material.

[0025] Advantageously, the plate is characterised in that the reflective material is a reflective film. Advantageously, the panel is characterised in that the height of the projections is at least 5 times greater than the thickness of the biofilm.

[0026] Advantageously, the panel is characterised in that the width of the projection covered with reflective foil is between 0.05 and 0.2 times the width of the light panel.

[0027] Advantageously, the panel is characterised in that the light source is distributed along the entire length of the side edges of the panel, advantageously the light source is selected from the group comprising: LEDs, halogen bulbs, fluorescent bulbs, traditional filament bulbs.

[0028] Another subject of the invention is a plate photobioreactor, characterised in that it comprises a housing connected to a housing base and at least one light plate as defined by the invention, wherein at least one carbon dioxide inlet and at least one oxygen outlet are located on one of the walls in the housing, a nutrient distribution channel is attached to the upper edge of the light plate, and a nutrientoutlet connected to at least one flow-through nutrient tank and at least one nutrient collection channel is provided in the bottom of the base, the nutrient tank is equipped with a nutrient inlet to which a nutrient supply pipe is attached and a nutrient outlet which is connected to at least one pipe for discharging used nutrient, and the flow-through tank has at least one pump connected to the nutrient distribution channel by at least one nutrient delivery pipe.

[0029] Advantageously, the photobioreactor is characterised in that the nutrient collection channel is equipped with a drain channel.

[0030] Advantageously, the photobioreactor is characterised in that the nutrient outlet is connected to the flow-through nutrient tank by means of a nutrient drain channel.

[0031] Advantageously, the photobioreactor is characterised in that the light plate is mounted in vertical profiles which are attached to the base of the housing by means of joints.

[0032] Advantageously, the photobioreactor is characterised in that the edge profiles are covered with a reflective film.

[0033] Advantageously, the photobioreactor is characterised in that the nutrient distribution channel extends along the entire length of the upper edge of the light panel.

[0034] Advantageously, the photobioreactor is characterised in that perforations are made in the bottom of the nutrient distribution channel.

[0035] Advantageously, the photobioreactor is characterised in that the nutrient distribution channel is attached to the narrower side walls of the housing by means of brackets.

[0036] Advantageously, the photobioreactor is characterised in that the light plate is equipped with a biomass scraping device which is attached to vertical profiles.

[0037] Another subject of the invention is a biomass production system, characterised in that it comprises at least two interconnected photobioreactors according to the present invention.

[0038] Thanks to its design, the invention achieves a very high concentration of photosynthetic organisms such as microalgae, cyanobacteria or photosynthetic bacteria by providing light on both sides of the resulting biofilm. Most of the light is introduced into the interior of a plate made of a substantially transparent material that allows light to be introduced, scattered and distributed. When light from LEDs is introduced into the edge of the plate made of transparent polymer material, a series of optical phenomena occur that allow for effective scattering and distribution of light throughout the plate. This increases the efficiency of the co2sequestration process while significantly reducing light loss. Part of the light generated by the LEDs is emitted at the outer surface of the plate, thus providing light for microorganisms located on the outer side of the biofilm layer. This also allows the outer layer of biofilm on adjacent plates to be illuminated. The nutrient medium introduced onto the surface of the light panels is also introduced onto the edges with LEDs mounted on them, which allows the heat generated by the LEDs to be effectively dissipated. According to this invention, it is possible to operatea photobioreactor with light panels completely immersed in the nutrient medium. The method of supplying light to enclosed volumes such as the interiors of light plates and the gaps between biofilms prevents the loss of light flux to the outside and at the same time ensures the effective use of periodically supplied light. The efficiency of microalgae and cyanobacteria cultivation in photobioreactors depends on the precise delivery of artificially generated light.

[0039] According to this invention, the light source may be any source selected from the group comprising: LEDs, halogen bulbs, fluorescent bulbs, and traditional filament bulbs.

[0040] According to this invention, the light panel may be made of any essentially transparent synthetic or inorganic material with light-transmitting properties, in particular polymethyl methacrylate (PM MA), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polycarbonate (PC), polyethylene film (PEF), aluminosilicate glass, borosilicate glass, optical glass, optical glass fibre.

[0041] According to this invention, "essentially transparent material" means that a material with lighttransmitting properties may be a completely transparent material, may be coloured, or may be a combination of, for example, a coloured (e.g. milky) outer surface of a light panel and a transparent interior of the light panel, in each case, this material must allow light to be introduced, scattered or distributed. Light introduction, light distribution and light scattering are properties also described by physical parameters such as, among others, the refractive index and light transmittance in the material . The introduction of light into a medium is a phenomenon in which light rays pass from one medium to another, often leading to their refraction or reflection. Light distribution is a process in which light radiation is scattered or directed in different directions within a given medium. Light scattering is a phenomenon involving the separation and directional propagation of light as it passes through a medium, causing light rays to reflect, refract or scatter in different directions.

[0042] According to this invention, a photobioreactor may contain more than one light plate without limiting the number of light plates. The design of the plate photobioreactor is modular and depends on the user's needs. Depending on the needs, the plate photobioreactor can be expanded, i.e. it can contain 10 light plates, 50 light plates or 1000 light plates (any number), which are enclosed in a correspondingly larger cuboid housing. The sizes of the photobioreactor light plate and the rectangular enclosure are not limited in any way. Each time a plate photobioreactor is designed, the dimensions of the light plate and the enclosure are adapted to the location where the plate photobioreactor will be installed, and therefore they can be of any size.

[0043] According to this invention, the light panel is equipped with at least two projections, which are made along the vertical edges along their entire length. The number of projections in the light panel is important for introducing, diffusing or distributing light, and this number can be arbitrary, depending on the requirements. In addition to the projections attached to the edges of the panel on both sides,additional projections may be made directly in the light panel or on the light panel, depending on the method of manufacturing the panel. These projections may form an integral part of the light panel in the case of mass production, or they may be elements attached to the flat surface of the light panel in the form of angle brackets or flat bars in the case of retail production, depending on expectations and needs.

[0044] According to the present invention, the phrase "the light panel contains at least one additional protrusion connected to the flat part of the light panel" means that the at least one additional protrusion is connected to the flat part of the panel at any location where there are no protrusions.

[0045] According to this invention, the height of the projections is adjusted to the technologically assumed thickness of the biofilm. The height of the projections is approximately 5 times greater than the thickness of the biofilm, with the height of each projection measured from the flat part of the light panel to the end edge of the projection. In turn, the width of the protrusion covered with reflective foil may range from 0.05 to 0.2 of the total width of the light panel.

[0046] The upper, flat surfaces of the plate projections are covered with a reflective material in the form of a reflective film. This material is shaped in such a way that the light entering the projection changes its direction of propagation and is guided parallel to the flat surface of the plate. The light thus directed outside the protrusion is then used by microalgae or cyanobacteria located on the outside of the biofilm, resulting in an increase in the thickness of the layer of active microalgae or cyanobacteria participating in the CO2sequestration process. As a result, the efficiency of the CO2sequestration process increases by 20-30%.

[0047] According to the present invention, the refractive indices for the materials used and at a light wavelength in the range of 400-700 nm are as follows:

[0048] polymethyl methacrylate PM MA - 1.492; polyethylene - 1.33; polypropylene - 1.46-1.49; polyethylene terephthalate - 1.57; polycarbonate - 1.58; aluminosilicate glass - 1.50-1.53; borosilicate glass - 1.47-1.52; optical glass - 1.48-1.95; optical glass fibre - 1.44-1.50. The refractive index for the material used according to the invention should be in the range of 1.30-1.95, preferably 1.30-1.70, preferably 1.30-1.50, most preferably 1.30-1.40, with a light wavelength in the range of 400-700 nm. The transmittance coefficient for the material used according to the invention should be in the range of 80-100%, preferably 85-100%, more preferably 90-100%, most preferably 95-100% at a wavelength in the range of 400-700 nm.

[0049] According to the present invention, the transmittance coefficients for the materials used and at a light wavelength in the range of 400-700 nm are as follows:

[0050] polymethyl methacrylate PM MA - 94%; polyethylene - 82%; polypropylene - 80-90%; polyethylene terephthalate - 80-90%; polycarbonate - 88-90%; aluminosilicate glass - >90%; borosilicate glass ->90%; optical glass - >90%; optical glass fibre - >90%.According to this invention, the term "nutrient" means an aqueous solution of biogenic substances.

[0051] The subject of the invention presented in the examples of implementation is shown in the drawing, where Fig. 1 shows a plate photobioreactor containing a single light plate in an axonometric view from one side, Fig. 2 shows a plate photobioreactor containing a single light plate in an axonometric view from the other side, Fig. 3 shows a plate photobioreactor containing a single light plate in a front view, Fig.4 shows the light plate in a front view, Fig. 5 shows the light plate with vertical profiles in an axonometric view, Fig. 6 shows the light panel with vertical profiles in a front view, Fig. 7 shows the light panel in a cross-section showing the arrangement of projections in the light panel for the variant with four projections and illustrating the detailed mechanism of light flow inside and outside the light panel, Fig. 8 shows the light panel in front view illustrating the arrangement of the light source on the panel and the schematic propagation of light in the light panel, Fig. 9 shows a block diagram of a series-connected photobioreactor system for biomass production, Fig. 10 shows a diagram of a photobioreactor with multiple light panels , where A shows a photobioreactor containing 10 light panels, B shows a photobioreactor containing 20 light panels, and C shows a photobioreactor containing 30 light panels.

[0052] A photobioreactor with photosynthetic microorganisms offers many advantages, particularly in terms of environmental protection and the production of valuable raw materials. The advantage of the solution according to the invention is the reduced electricity consumption associated with the process of irradiating microorganisms, which translates into lower costs associated with co2sequestration. In addition, significantly less space is needed to install photobioreactors, as their volume is reduced. An important advantage of the present invention is the high scalability of the photobioreactor, namely the possibility of modular expansion of the photobioreactor by increasing the number of light plates placed in the housing at a short distance from each other and the possibility of any configuration of light plates connected to each other (in series / parallel / hybrid).

[0053] Example 1 - Plate photobioreactor with a single light plate for biomass production

[0054] The plate photobioreactor essentially comprises a cuboid housing 1, in which a light plate 2 is mounted vertically and essentially perpendicular to the base of the housing 3. The base of the housing 3 has the shape of a rectangular tank. The light plate 2 is equipped with vertical profiles 4, which are attached to the base of the housing 3 by means of joints 5 allowing the light plate 2 to be positioned essentially vertically. The light plate 2 is made of a transparent material that allows light to be introduced, scattered or distributed. Edge profiles 4a with mounted light sources 4b in the form of LED strips are attached to the vertical edges 2a, 2b of the light panel 2 so that the light beam is directed towards the inside and outside of the light panel 2. The light panel 2 is equipped with at least two projections 2e,which are made along the vertical edges 2a, 2b over their entire length. Depending on the desired dimensions of the light panel 1, the number of projections 2e may increase. Additional projections 2e may be made directly in the light panel 2 (Fig. 6), whereby the number of projections in the light panel 2 is not limited, and the projections 2e made in or on the light panel 2 extend over the entire length of the panel. The edge profiles 4a and projections 2e may additionally be covered with a reflective film 15. The photobioreactor housing 1 is open on the side of the photobioreactor housing base 3. In the housing 1, on the side wall at the edge of the plate 2a and above the base of the housing 3, there is a carbon dioxide inlet 6, while on the opposite side wall of the housing 1, under the upper edge 2c of the light plate 2, there is an oxygen outlet 7. Above the upper edge 2c of the light plate 2, there is a nutrient distribution channel 8. The nutrient distribution channel 8 is equipped with perforations 8a, which are made in the bottom of the nutrient distribution channel 8 and arranged above the surface of the upper edge 2c of the light plate 2. The nutrient distribution channel 8 is attached to the narrower side walls of the housing 1 by means of brackets 9. The light plate 2 is additionally equipped with a biomass scraping device 10 movably attached to the light plate 2. A nutrient collection channel 11 is attached to the bottom of the base 3, which is equipped with a drain channel 12. A nutrient outlet 13 is made in the base 3, which is connected to the flow-through nutrient tank 14 by means of the nutrient drain channel 12. The nutrient tank 14 is equipped with a nutrient inlet 16, to which a nutrient supply pipe 17 is attached, and a nutrient outlet 18, which is connected to a waste nutrient discharge pipe 19. A discharge pump 20 is located in the flow-through tank 14, which is connected to the nutrient distribution channel 8 by means of a nutrient discharge pipe 22. Biofilm 23 (excess biomass) is discharged into the nutrient tank 14 and, together with the used nutrient, is discharged through the used nutrient discharge pipe 19.

[0055] Example 2 - Light panel

[0056] Light panel 2 is a sheet made of transparent material that allows light to be introduced, diffused and distributed. Light panel 2 is equipped with at least two projections 2e, which are made of or attached to the side edges 2a and 2b of light panel 2 (Fig. 7A). Light panel 2 may contain more than two projections 2e, which are made or attached directly to the light panel (Fig. 7B). The aforementioned projections 2e may form an integral part of the light panel 2, or they may be elements attached to the flat surface of the light panel 2 in the form of flat bars made of transparent materials that allow light to be introduced, scattered or distributed. The projections 2e may optionally be covered with a reflective film 15, wherein the reflective film 15 advantageously covers the projections 2e from the upper edge 2c to the lower edge 2d of the light panel 2. The height of the projections 2e is adapted to the technologically assumed thickness of the biofilm 23, and the height of the projections 2e is approximately 5 times greater than the thickness of the biofilm 23. The width of the projection 2ecovered with reflective film 15 is between 0.05 and 0.2 of the total width of the light panel 2. Light sources are attached to both vertical side edges 2a, 2b of the light panel 1, one light source 4b to each vertical side edge 2a, 2b, preferably in the form of a strip with LEDs.

[0057] Example 3 - Light distribution mechanism in a light panel

[0058] Light panel 2 is designed in such a way that microorganisms in the form of microalgae, cyanobacteria and photosynthetic bacteria accumulate on light panel 2, forming a biofilm 23 on both surfaces of light panel 2. At the same time, light energy is supplied to each biofilm 23 on both of its surfaces, i.e. on the surface attached to light panel 2 and on the outer surface of biofilm 23, as illustrated by the directions of light emission 21 (Fig. 7). This method of illumination is made possible by the thickened side edges 2a and 2b resulting from the introduction of projections 2e located inside the edge profiles 4a and projections 2e located on the flat surface of the light panel 2 in the form of flat bars. In order to achieve even better results and retain the light inside the panel 2, the aforementioned flat bars may be covered with a reflective film 15. The reflective film 15 directs the light to the vertical edges of the projections 2e. The reflective film 15 covers the projections 2e from the upper edge 2c to the lower edge 2d of the light panel 2 and allows light to be emitted with the participation of the vertical edge of the projection 2e. The width of the projection 2e covered by the reflective film 15 is adjusted as needed, but is usually between 0.05 and 0.2 of the total width of the light panel 2. The height of the projections 2e is adjusted as needed and to the technologically assumed thickness of the biofilm 23, which is approximately 5 times greater than the thickness of the biofilm 23. The light sources 4b located in the edge profiles 4a emit light. The light is introduced into the entire side surface of edges 2a and 2b. Then, part of the light is introduced into the narrower part of the light panel 2, i.e. the part of the panel without the projection 2e, which is covered with the growing biofilm 23, and the other part of the light is directed outside towards the biofilm 23 through the perpendicular surface of the projection 2e. With edge profiles 2a and 2b, the amount of light emitted to the outer sides of the light panel 2 towards the biofilm 23 accounts for 5% to 15% of the total amount of light supplied to the side surfaces of edges 2a and 2b. On the other hand, each projection 2e located on the surface of the light panel 2 receives between 2% and 5% of the total light supplied by the LEDs located on the LED strips 4b. The light panel 2 allows for fully controlled distribution of the light flux and directs the distributed light to the desired areas of biofilm growth (photosynthetic microorganisms). The created light distribution causes the biofilm 23 to receive light energy from two sides, and the microorganisms forming the biofilm 23 have more favourable conditions for photosynthesis.

[0059] The use of the light panel according to this invention also results in co2sequestration, which increases by at least 50%. Biofilm growth increases from 40 gsm / m2d to 60 gsm / m2d. At the same time, biofilm 23 illuminated on both sides has a more favourable structure, which deteriorates significantly in theabsence of light. Biofilm 23 that is not illuminated has many dead microorganisms that become denser, and in the absence of free space inside biofilm 23, access to the nutrient flowing down the surface of biofilm 23 is difficult. The diffusion of CO2 diffusion, whichis necessary for the growth of microorganisms, and the outflow of oxygen outside biofilm 23, which as a product of metabolism is an inhibitor of microorganism growth, is limited.

[0060] Example 4 - A system of photobioreactors connected in series for biomass production

[0061] Large, expandable installations for the production of biomass from photosynthetic microorganisms must be equipped with additional facilities and equipment. Due to the modularity of a single photobioreactor, it is possible to expand the installation and increase the number of photobioreactors, as well as to increase the number of light plates in a photobioreactor or photobioreactor system. In the attached example, the process of CO2sequestration and biomass multiplication takes place in five photobioreactors 24, 25, 26, 27, 28, which have a cascade gas flow and parallel nutrient supply. In large installations, artificial nutrient can be replaced, for example, with wastewater from the agri-food industry, which contains large amounts of biogenic compounds. Examples include wastewater from dairies, breweries and meat processing plants. The situation is similar for the supplied carbon dioxide gas. It can come from biogas combustion plants, beer and yeast production, but also from industry, for example from cement plants. In the proposed system, CO2in the amount of 120 kg CO2 / d. To accomplish this task, the installation has 5 photobioreactors. Each of them is equipped with 50 light panels measuring 2.0 m wide and 3.0 m high. The surface area on which the biofilm 23 grew was 3000m2 .

[0062] The photobioreactor system was as follows: the medium in the form of mechanically pre-treated dairy wastewater was averaged in a 10 m3tank, in which a mechanical agitator was installed to improve the process of averaging the wastewater composition. The wastewater then flowed by gravity to the pumping station 30 and was pumped through a pressure pipe 20 to each photobioreactor 24-28, from where it flowed through a channel 12 to the nutrient filtering devices. These are two drum filters 31, 32 with a diameter of 1.0 m and a length of 0.8 m. Drum filter 31 had a filter material perforation of 50 pm, while the second drum filter 32 used a material with a perforation of 20 pm. The filtered medium flowed into the pumping station 34, while the concentrated microalgae biomass was discharged into a storage tank 33 with a capacity of 20 m3, from which it was taken for further processing. Two pumps were installed in the pumping station 34, one of which pumped part of the nutrient solution out of the installation, while the other pump in the pumping station 34 directed the filtered nutrient solution to the averaging tank 29. The number of pumps in the pumping station 34 can be adjusted as needed. The installation utilised gas from a power generator burning biogas from the fermentation chamber. The gas contained 15% carbon dioxide. Before being fed into the firstphotobioreactor, the gas flowed through a measuring device 35 containing a pressure reducer, a gas meter and shut-off valves. The concentration of carbon dioxide in the gas flowing through the photobioreactors decreased after absorption by microalgae, but at the same time the concentration of oxygen in the gas increased. After the last photobioreactor 28, the quantity and quality of the gas was measured in measuring device 36, from which the purified gas was discharged into chimney pipe 37 and into the atmosphere. In the proposed installation, the concentration of CC can be greatly reduced and the efficiency of the sequestration process can reach up to 85%. At the same time, the wastewater used as a nutrient medium is purified, as microorganisms utilise biogenic substances. The amount of organic matter is also reduced with the participation of aerobic bacteria, for which microalgae produce oxygen. The result is high biomass growth rates of up to 80 kgsm / d.

[0063] Example 5 - Experimental research on algae production

[0064] Experimental studies were conducted using a plate photobioreactor containing a single light plate. The photobioreactor 1 housing had the following dimensions: width 0.2 m, height 1.3 m, length 1.2 m. The carbon dioxide inlet 6 and oxygen outlet 7 had a diameter of 8 mm, while the nutrient delivery pipe 22 had a diameter of 12 mm. The base of the housing 3 was a flat rectangular steel tank measuring 0.3 m x 1.3 m x 0.1 m. Underneath the base of the housing 3, there was a plastic tank 14 with a cover, with a capacity of 90 litres, which contained 70 litres of nutrient medium, a centrifugal pump 20 and an electric heater immersed in the nutrient medium, maintaining the temperature of the nutrient medium in the range of 27°C to 29°C. Inside the housing 1, there was a light panel 2 measuring 1.0 m x 1.0 m x 0.005 m with double-sided illumination of the biofilm 23, which covered both surfaces of the light panel 2. The light panel 2 had five projections 2e, each projection 2e having the following dimensions: width 10 mm, length 1000 mm and thickness 5 mm. The projections 2e were covered with a reflective film 15 enabling the light to be directed onto the vertical edges of the projections 2e. Light sources 4b in the form of LED strips were attached to both opposite projections 2e located on the vertical edges 2a and 2b of light panel 2 to ensure uniform illumination. Each strip consisted of 18 LEDs spaced at equal distances from each other, including 12 red light-emitting diodes and 6 blue lightemitting diodes, allowing the lighting conditions to be adjusted to specific biological needs, whereby the strips containing LEDs and the arrangement of LEDs do not constitute a limitation of this experiment. The LEDs were arranged in the following repeating sequence: 2 red LEDs and 1 blue LED. During use, the power consumption was 19W per LED strip 4b. The amount of light supplied was determined using a measuring device in the form of an E3PB-3 OHSP350UVP meter.

[0065] Both surfaces of the light panel 2, namely the flat surfaces of the panel (there is no biofilm on the protrusions), were covered with biofilm 23 produced by microalgae of the species Chlorella vulgaris, for which the composition of the medium was prepared according to the recipe provided by the AlgaeBanks. The medium was pumped through a pumping pipe 22 into a medium distribution channel 8 in the form of a plastic pipe with a diameter of 30 mm, perforated with holes 8a with a diameter of 5 mm, spaced 50 mm apart. The medium flowed evenly over the surface of the biofilms 23 and from the light plate 2 it entered the medium collection channel 11 with a width of 100 mm, so that through channel 12 with a diameter of 50 mm it was reintroduced into the flow-through medium tank 14. The technical gas used in the experimental studies was carbon dioxide CO2with a concentration of 100%. The tests were conducted over a period of 10 days. During this time, measurements were taken of the amount of CO2consumed by the microalgae and the decreasing concentration of biogenic compounds such as nitrogen, phosphorus and potassium. The tests were repeated 10 times under the same conditions. A biofilm load of 23 incoming CO2 of 10g CO2 / m2per day. The efficiency of the CO2 sequestration process increased during the 10-day experiment, reaching 85% efficiency on the last day. Tests of the medium composition showed that the amounts of biogenic compounds were sufficient for microalgae. However, after the experiment, the nutrient tank 14 was emptied and new portions of nutrient were added. It was shown that the biofilm growth rates were high and during one experiment in the photobioreactor, microalgae biomass weighing from 70g dry weight to 100g dry weight was produced.

[0066] The results obtained were compared with the results of an experiment with a photobioreactor, in which a flat plate without protrusions and without double-sided lighting was used. The same species of microalgae, Chlorella vulgaris, was used for cultivation, but the efficiency of the sequestration process was lower, reaching a maximum of 70%. Lower microalgae biomass increases were also obtained in each experiment, ranging from 50 g to 65 g of dry weight. In addition, a different biofilm structure was observed, which tended to exfoliate as the experiment progressed, leading to the destruction of the photosynthetic microorganism culture.

[0067] Final conclusions:

[0068] The light plate and the photobioreactor containing at least one light plate are structural solutions that create very good conditions for the development of microorganisms colonising both of its surfaces, including microalgae, cyanobacteria and photosynthetic bacteria. The biofilm created by microorganisms is powered by light energy from the side of the plate to which it is attached, with light also reaching it from the outside of the biofilm.

[0069] Uniform irradiation of the biofilm prevents light inhibition. The method of irradiating microorganisms using the light panel according to the invention allows the light output of the LEDs to be reduced by 15% compared to a panel that emits light only from the inside. Any number of light panels can be installed in photobioreactors, but if more than 30 light panels are used, they should be divided into sections, which will facilitate the operation of devices removing excess microorganism biomass andensure proper distribution of the nutrient medium dosed onto the edges of the light panels. The specific design of the light panels allows them to be used in reactors that can operate when fully submerged or when the reactors are above the nutrient surface. In photobioreactors with doublesided light-introducing plates, CO2 sequestration efficiency of over 85% can be achieved, resulting in larger amounts of biomass formed on the surface of the light plates and, compared to other closed reactors used, biomass growth rates that are several times higher. Additionally, it is worth noting that operating costs are reduced due to lower electricity consumption and smaller space requirements. The co2sequestration process can be carried out regardless of the co2concentration in the incoming gas, and the gas may contain 100% CO2. What is more, the CO2sequestration process2 process can be carried out in any atmospheric conditions, without an external supply of CO2. The nutrient medium can be artificially prepared, but it can also be various types of sewage, for example from the agri-food industry, as has been proven in experiments with dairy sewage. In addition to high CO2sequestration efficiency, large amounts of biomass of microorganisms forming biofilm are obtained.

[0070] List of designations:

[0071] 1 - photobioreactor housing,

[0072] 2 - light plate,

[0073] 2a, 2b - vertical side edges of the light panel,

[0074] 2c - upper edge of the light panel,

[0075] 2d - bottom edge of the light panel,

[0076] 2e - projections,

[0077] 3 - housing base,

[0078] 4 -vertical profiles,

[0079] 4a - edge profiles,

[0080] 4b - light source (LED strips),

[0081] 5 - joints,

[0082] 6 - carbon dioxide inlet,

[0083] 7 - oxygen outlet,

[0084] 8 - nutrient distribution channel,

[0085] 8a - perforations in the bottom of the distribution channel,

[0086] 9 - supports,

[0087] 10 - biomass scraper,

[0088] 11 - nutrient collection channel,

[0089] 12 - drainage channel,

[0090] 13 - nutrient outlet,- flow-through nutrient tank, - reflective film,

[0091] - nutrient inlet,

[0092] - nutrient supply pipe,

[0093] - nutrient outlet,

[0094] - waste medium discharge pipe, - pump (e.g. pressure pump), - light direction,

[0095] - nutrient delivery pipe,

[0096] - biofilm,

[0097] - photobioreactor 1,

[0098] - photobioreactor 2,

[0099] - photobioreactor 3,

[0100] - photobioreactor 4,

[0101] - photobioreactor 5,

[0102] - averaging tank,

[0103] - nutrient pumping station,

[0104] - drum filter 1,

[0105] - drum filter 2,

[0106] - biomass tank,

[0107] - filtered nutrient pump station, - gas measuring device,

[0108] - purified gas measuring device, - gas chimney.Literature:

[0109] 1. Yahui Sun, Yun Huang, Qiang Liao, Qian Fu, Xun Zhu - "Enhancement of microalgae production by embedding hollow light guides to a flat-plate photobioreactor", Bioresource Technology Vol. 207, May 2016, Pages 31-38, doi.org / 10.1016 / j.biortech.2016.01.136

[0110] 2. Pengfei Cheng, Yuanzhu Wang, Tianzhong Liu, Defu Liu - "Biofilm Attached Cultivation of Chlorella pyrenoidosa Is a Developed System for Swine Wastewater Treatment and Lipid Production", Front. Plant Sci., 21 September 2017; Sec. Plant Biotechnology, Vol. 8 - 2017; doi.org / 10.3389 / fpls.2017.01594

[0111] 3. Suh LS., Joo, H.N., Lee, C.G. - "A novel double-layered photobioreactor for simultaneous Haematococcus pluvialis cell growth and astaxanthin accumulation" J. Biotechnol. 2006, 125, 540-546

[0112] 4. Jairo Hernan Moreno Osorio, Gabriele Pinto, Antoninio Pollio, Luigi Frunzo, Piet Nicolaas Luc Lens, Giovanni Esposito - "Start-up of a nutrient removal system using Scenedesmus vacuolatus and Chlorella vulgaris biofilms", December 2019; Bioresources and Bioprocessing 6(1), DQI:10.1186 / s40643-019-0259-3

[0113] 5. Tianzhong Liu, Junfeng Wang, Qiang Hu, Pengfei Cheng, Bei Ji, Jinli Liu, Yu Chen, Wei Zhang, Xiaoling Chen, Lin Chen, Lili Gao, Chunli Ji, Hui Wang - "Attached cultivation technology of microalgae for efficient biomass feedstock production", Bioresource Technology 127 (2013) 216-222, http: / / dx.doi.Org / 10.1016 / j.biortech.2012.09.100

[0114] 6. Miroslaw Krzemieniewski - "CO2 sequestration installations with an algae reactor - example solutions, construction and operating costs", 21 November 2021 Polska Rolna Nowy Przeglqd Mleczarski

Claims

Patent claims1. A light panel, characterised in that it comprises at least two projections (2e) connected to the side edges (2a) and (2b) of the light panel (2), wherein a light source (4b) is attached to at least two projections (2e), wherein the light panel (2) and the projections (2e) are made of a material capable of introducing, diffusing or distributing light.

2. The panel according to claim 1, characterised in that the material capable of introducing, scattering or distributing light is a substantially transparent material.

3. The panel according to claim 2, characterised in that the essentially transparent material is an essentially transparent polymeric material or an essentially transparent inorganic material.

4. A plate according to any of claims 1-3, characterised in that the essentially transparent polymeric or inorganic material has a refractive index in the range of 1.30-1.95, preferably 1.30-1.70, preferably 1.30-1.50, most preferably 1.30-1.40, at a wavelength in the range of 400-700 nm.

5. A plate according to any of claims 1-3, characterised in that the essentially transparent polymeric or inorganic material has a transmittance in the range of 80-100%, preferably 85- 100%, more preferably 90-100%, most preferably 95-100% at a wavelength in the range of 400-700 nm.

6. A plate according to any of claims 2-5, characterised in that the essentially transparent polymeric material is selected from the group comprising: polymethyl methacrylate, polyethylene, polypropylene, polyethylene terephthalate, polycarbonate.

7. A panel according to any of claims 2-5, characterised in that the essentially transparent inorganic material is selected from the group comprising: aluminosilicate glass, borosilicate glass, optical glass, optical glass fibre.

8. A panel according to any of claims 1-7, characterised in that it comprises at least one additional projection (2e) connected to the flat part of the light panel (2).

9. A panel according to any of claims 1-8, characterised in that it comprises four projections (2e), wherein two projections are connected to the side edges (2a) and (2b) of the light panel (2), and the other two projections (2e) are connected to the flat part of the light panel (2).

10. A panel according to any of claims 1-9, characterised in that the projections (2e) are covered with a reflective material.

11. The plate according to claim 10, characterised in that the reflective material is a reflective film (15).

12. A plate according to any of claims 1-11, characterised in that the height of the projections (2e) is at least five times greater than the thickness of the biofilm (23).

13. A panel according to any of claims 1-12, characterised in that the width of the protrusion (2e) covered with a reflective film (15) is between 0.05 and 0.2 times the width of the light panel (2).

14. A plate according to claim 1, characterised in that the light source (4b) is distributed along the entire length of the side edges of the plate (2a, 2b), preferably the light source (4b) is selected from the group comprising: LEDs, halogen bulbs, fluorescent bulbs, traditional filament bulbs.

15. A plate photobioreactor, characterised in that it comprises a housing (1) connected to a housing base (3) and at least one light plate (2) as defined in any of claims 1-14, wherein at least one carbon dioxide inlet (6) and at least one oxygen outlet (7) are provided on one of the walls of the housing (1), and at least one nutrient distribution channel is attached to the upper edge (2c) of the light plate (2). (6) and at least one oxygen outlet (7) is located on one of the walls in the housing (1), a nutrient distribution channel (8) is attached to the upper edge (2c) of the light plate (2), and a nutrient outlet (13) connected to at least one flow-through nutrient tank (14) and at least one nutrient collection channel (11), while the nutrient tank (14) is equipped with a nutrient inlet (16) to which a nutrient supply pipe (17) is attached, and a nutrient outlet (18) connected to at least one used nutrient discharge pipe (19), and the flow- through tank (14) contains at least one pump (20) connected to the nutrient distribution channel (8) by means of at least one nutrient delivery pipe (22).

16. Photobioreactor according to claim 15, characterised in that the nutrient collection channel (11) is equipped with a drainage channel (12).

17. A photobioreactor according to any of claims 15-16, characterised in that the nutrient outlet (13) is connected to the flow-through nutrient tank (14) by means of a nutrient drain channel (12).

18. A photobioreactor according to any of claims 15-17, characterised in that the light plate (2) is mounted in vertical profiles (4) which are attached to the base of the housing (3) by means of joints (5).

19. A photobioreactor according to any of claims 15-18, characterised in that the edge profiles (4a) are covered with a reflective film (15).

20. A photobioreactor according to any of claims 15-19, characterised in that the nutrient distribution channel (8) extends along the entire length of the upper edge (2c) of the light plate (2).

21. A photobioreactor according to any of claims 15-20, characterised in that perforations (8a) are made at the bottom of the nutrient distribution channel (8).

22. A photobioreactor according to any of claims 15-21, characterised in that the nutrient distribution channel (8) is attached to the narrower side walls of the housing (1) by means of brackets (9).

23. A photobioreactor according to any of claims 15-22, characterised in that the light plate (2) is equipped with a biomass scraping device (10) which is attached to vertical profiles (4).

24. A biomass production system, characterised in that it comprises at least two interconnected photobioreactors as defined in any of claims 15-23.

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