WO2020161519A1

WO2020161519A1 - Bioreactor for stationary biofilms of photosynthetically active microorganisms

Info

Publication number: WO2020161519A1
Application number: PCT/IB2019/050916
Authority: WO
Inventors: Benjamin Herzog
Original assignee: Solaga Ug
Priority date: 2019-02-05
Filing date: 2019-02-05
Publication date: 2020-08-13
Also published as: AT523817A2; DK202100791A1

Abstract

A device for sustaining the life of a stationary biofilm of phototrophic microorganisms and a method for purifying air and producing substances. Life is sustained in a low-maintenance and low-energy manner for a prolonged period of time. The bioreactor includes a planar housing having a transparent front wall and air openings. The biofilm is situated on a growth and distribution mat, which collectively adjoin the back wall. A tank supplies the biofilm with medium. The biofilm is not grown in the housing, but only inserted therein. Skimming precautions are not necessary. Owing to the simple construction, the biofilm can be rapidly exchanged. The water demand is low. Using the method presented here, it is possible to take up a relatively large number of harmful substances in a low-energy and low-maintenance manner. Likewise possible is efficient production of organic substances of value through simple media and air exchange and through wash-off.

Description

Title: Bioreactor for stationary biofilms from photosynthetically active microorganisms

The present invention relates to a bioreactor for keeping a stationary biofilm from photosynthetically active microorganisms alive and a method for air purification and substance production.

The interest in photosynthetically active microorganisms (PAM) is not only increasing in biotechnology. They are receiving increasing attention, especially in the energy and food industries. Algae in the narrower sense of the word are above all photosynthetically active microorganisms. To include green algae, cyanobacteria, anoxygenic, phototrophic bacteria and certain archaebacteria. Compared to plant-based systems, they show much higher growth rates per area and can also be grown on sealed surfaces without soil. Their metabolism differs from animal and partly also from plant systems in such a way that a variety of different metabolic products can be produced by them. PAM are cultivated in bioreactors. This mainly takes place in liquid reactors. In these bioreactors, the PAM are mainly circulated by mechanical forces or gassing flows so that all cells are irradiated with light. In addition, energy-intensive gassing is necessary so that all cells receive the CO2 they need. In most cases of application, the PAM are harvested by separating them from the medium by centrifugation, which uses a lot of energy. The water in the medium is used up.

In contrast, so-called biofilms made from PAM have a number of advantages. A biofilm is a thin film of slime in which populations of microorganisms are organized. The largest part of all microorganisms occurs naturally in such mostly heterogeneous biofilms. The biofilm offers them many advantages. In this way they can fix themselves permanently to objects, protect themselves from intruders and live in symbiosis with other organisms. The mucus layer is an exopolysaccharide layer (EPS) consisting predominantly of polyuronides, ie polysaccharides which contain uronic acids such as. B. D-mannuronic acid, D-galacturonic acid or D-glucuronic acid. The uronic acids are always in pyranose form and give the macromolecules an acidic character and the ability to store water and thus to form a gel. It was found in studies that the cells in the biofilm network also exchange substances with one another, so that the cells located further down are also supplied with the substances produced by light, oxygen is removed and C0 _{2 is} also transported in and distributed in the form of FICO3 becomes.

The EPS protects the PAM against dehydration, large temperature differences, salt stress, strong radiation and predators. This enables the PAM to survive much better in nature. It is intended to make PAM biofilms usable for humans. Their use in water purification is being examined in part. There they are supposed to absorb phosphates and nitrates. However, these pollutants are also fertilizers for the PAM, so that the biofilm would have to grow and have to be harvested. However, there are no valid usage scenarios for this, especially since a protective skin once it has been formed is not expanded. Plant stalks or leaves, which are comparable to the organism biofilm, do not grow in width either. Therefore, only the use of a stationary biofilm comes into consideration. Stationary biofilms no longer grow. They have their own metabolism and an excess metabolism. The excess metabolism, which can lead to the accumulation or secretion of metabolic products, is mainly used when there is additional energy in the form of light.

Bioreactors for biofilms are known in the prior art. WO2014172691A4 discloses a culture system with a biofilm adhesive surface for, among other things, algae that have grown on a surrounding element that forms several accordion folds and is carried in a surrounding roadway. The circumferential folding system has some disadvantages, since it consumes a lot of energy, among other things. In addition, no stationary system is used. Finally, the movement can damage the biofilm. A bioreactor for PAM biofilms is also known from WO2014085869A1. Liquid-permeable layers then form a first surface on which photosynthetic microorganisms can be cultivated in order to form a biofilm. A second surface is in fluid communication with a source of fluid. The liquid permeable layer is rotated. This consumes additional energy. Last but not least, the system is designed for the ineffective growth of the biofilm. In the round system, the application and maintenance of the biofilm are much more difficult.

US10072239B1 discloses a system for growing at least one photosynthetic microorganism and for converting CO into O with reduced water consumption. The system includes a liquid transport capillary channel, a photosynthetic mixed culture biofilm and a liquid transport substrate which is positioned between and adjoins the capillary channel and the biofilm, the liquid transport rate being adjustable by adjusting the local air humidity. This system is based on the supply principle that trees use to supply their leaves with water. Only the salts that arise there are consumed by the leaves. In the system proposed here, it is not clear how the salts that remain during evaporation are used and how long the system will run as a result or, for example, loss of functionality. The liquid tank is always attached at the bottom, so that it has energetic disadvantages because the water is transported against the force of gravity. The whole system depends heavily on the available humidity. If this is excessive it will not work. The system is also geared towards the growth and not the stationary existence of the biofilms.

Various biofilm reactors have been developed in the non-patent literature. Naumann et al. have published a system in which microalgae are immobilized by self-adhesion on vertically oriented two-layer modules. The two-layer modules consist of glass fiber fleece, through which the culture medium is transported by gravity, and printer paper, which carries the algae on both surfaces of the modules. The growing microalgae are used for feeding aquacultures. A stationary biofilm is not cultivated. Furthermore, there is no reserve tank. The multi-module structure is complex and prone to contamination.

Podola et al. and Liu et al. propose a system in which an algal biofilm grows on a microporous membrane. A culture medium is located behind it. Several modules are supplied by one pump. In so-called biofilm-PBR (porous substrate bioreactors), biofilms grow on a fluid-distributing structure that is provided as a fastening for an internal supply channel on a hanging module. There is no immediately adjacent liquid tank. There are also several modules with bilateral alignment. The device is used exclusively for the growth of biofilms, that is to say the production of biomass, with the associated problems of harvesting and the regrowth of a self-contained system.

The present invention is intended to provide a bioreactor for keeping a stationary biofilm of photosynthetically active microorganisms alive for a longer period of time with a low-maintenance and low-energy operation.

The object is achieved by a bioreactor for a stationary biofilm from photosynthetically active microorganisms consisting of a rectangular, flat, elongated housing, one wall of the elongated wide side, the front wall, being at least partially made of transparent material and air openings in the side walls are. The biofilm grew on a porous material, the growth mat. A layer of material that is easy to distribute liquid, the distribution mat, is located underneath. The mats with the biofilm lie on the inside of the rear wall or are attached there. A tank with medium for supplying the biofilm is provided on the outside of the rear wall or as a protuberance of the housing, the tank being in communication with the interior of the housing via openings and having an opening for refilling. The advantage of the present solution is that a stationary biofilm can be obtained with little maintenance and energy. Rearing can take place in a different location. The biofilms are simply inserted into the housing. Since a stationary biofilm is used, no skimming precautions are necessary. With this method and this structure, biofilms could already be successfully kept alive in the laboratory for 2 years without any loss of CO ₂ uptake or other changes. The protective skin once formed in the form of the EPS is comparable to a cuticle.

Another advantage is the design and robustness. Due to the simple structure, the biofilm can be changed quickly and with little time-consuming if necessary. In addition, there is no need for complex sterilization. This easy handling means that it can also be used outside the laboratory: at home, in the office or as a stand-alone system outdoors.

Another benefit is that little maintenance is required. Since the biofilm no longer grows, the water requirement is low. On average, a 100 ml tank with a biofilm area of 30 x 40 cm and average humidity only needs to be refilled once or twice a month. The PAM only use as much as they actually need. Low-energy operation is possible thanks to the optimal distribution of the liquid in the growth mat and the distribution mat. Any metabolic end products or daughter cells that may occur can accumulate in the housing. In the absence of stressful conditions, the release of the latter was very rarely observed. The PAM also secrete substances that prevent the growth of undesirable organisms such as fungi and the like. Due to the structure of the bioreactor and the ease of use, a permanent and sustainable coexistence of microorganisms with a high potential for use with humans is now possible.

The housing is flat, i.e. there is a large front wall and a large back wall. The width of the side walls, the top and bottom walls is small compared to these areas. Air vents are located in the latter walls. The flat design enables passive air flow through the housing (chimney effect). Due to the light irradiation, the PAM produce warm air that rises upwards. Cold air flows in. This process also creates humidity that can be released outside. Especially in low-energy houses, dry, synthetic air, which is generated by large, energy-wasting filter systems, is a major problem. In addition, most of these houses are not allowed to be ventilated in order to avoid excessive energy loss. The elongated design is of great importance for user-friendliness for ergonomic and space-saving use outside the laboratory. Last but not least, the largest possible biofilm can be accommodated in an elongated container. There is also little shadowing.

The light enters through the transparent material on the front. This consists of glass or polymethyl methacrylate (acrylic glass, plexiglass). The medium differs depending on the PAM used. It is not provided with any fertilizer, especially not with nitrates and phosphates. The salt content is low, so that there is a sufficient concentration gradient between the dissolved substances and the air to be cleaned. It diffuses through the distribution mat and thus supplies the entire biofilm. In particular, the liquid will run down over time due to gravity.

The distribution mat is an absorbent mat, absorbent mat or absorbent fleece. The main property is the uptake and even distribution of liquid from a point source of liquid. It is advantageous if the mat has a fibrous structure due to the presence of microfibres. Materials can be found in diapers and mats for handling incontinence. The mat can consist of, for example, cellulose, polypropylene, copolymer fibers, bicofibers. It rests against the waxing mat. This can be, for example, a nonwoven, i.e. a structure made of fibers of limited length, continuous fibers (filaments) or cut yarns of any kind and of any origin, which are combined to form a nonwoven (a fiber layer, a fiber pile) and in a way have been connected to one another without crossing or intertwining yarns, as is the case with weaving, Knitting, knitting, lace manufacture, braiding and the manufacture of tufted products are all happening. This can include foils, papers or fiber-reinforced plastics.

A biofilm has grown on the growth mat. To generate the biofilm, the PAM are first grown in liquid culture and applied to the growth mat so that they can grow in there and form the exopolysaccharide layer. Both homogeneous and heterogeneous biofilms with different PAM or other species can be used. Of the PAM algae and cyanobacteria are phidophyceae as Axodine, Bacillariophyceae, Bryopsidophyceae, Chlorophyceae, Cyanobacteria, Dinophyceae, Eustigmatophyceae, Labyrinthulea, Mesostigmatophyceae, Pelagophyceae, Phaeophyceae, Phaeothamniophyccac, Pleurastrophyceae, Prasinophyceaer, Synurophyceae, Trebouxiophyceae, Ulvophyceae, Xanthophyceae, Gloeothecae, Plectonemae, Anabaena sp. and Nostoc sp. In particular, cyanobacteria are able to work effectively due to additional photopigments, even in poor light, as occurs in shady rooms. The PAM absorb light and partially convert it into heat. As a result, the air rises up in the housing and is forced out through the air openings. New air flows in (chimney effect). A thin film of liquid is present on the biofilm, at the interface of which gas can be exchanged with the air, similar to that in the lungs or the stomata of plants. Short diffusion paths enable rapid exchange with the cells. The medium with few components also flows past the air in the countercurrent principle (countercurrent principle).

Whether the tank is on the back or as a protuberance of the housing depends on which construction is easier to implement. This is particularly important when using 3D printing processes or higher quantities.

In a preferred embodiment, air openings are provided in the smallest walls, i. present in the bottom wall and the top wall. They are therefore opposite one another in a vertical axis. This arrangement makes optimal use of the chimney effect and the countercurrent principle. The shape of the air openings does not matter. The size is to be selected according to the desired air exchange rates. The larger they are, the more air can flow through them. This also depends on the environment, especially its humidity. In rooms, especially through radiators and radiators, where warm air flows upwards, there are mainly vertical currents, which are exploited by this structure.

In a further preferred embodiment, a filter or a grid, which has a minimum mesh size of 0.2 mm, is integrated or connected in the air openings. A filter, especially a grid in the openings with a minimum mesh size of 0.2 mm made of non-rusting materials such as stainless steel or plastic, effectively prevents insects from entering, but still allows air and dust through.

In a further preferred embodiment, the air openings are in particular extended inwardly as channels or there is a web on the inside of the bottom wall, so that a collecting basin is formed in both cases. Tubes or channels adapted to the hole format can be used as channels. The bar is located between the pane and the rear wall and connects to the air openings. This keeps the catch basin larger. The web can be an extension of an opening in the form of a wide gap. The catch basin created by the additional fixtures or protuberances serves as leakage protection if the liquid runs through the tank too quickly. Without a catch basin it could happen that the medium drips out through the air openings. The channels or the web are made of, for example, plastic and are preferably transparent so that more of the biofilm is visible to the outside. If possible, the length of the extension or the bar should be selected so that there is no shading of the biofilm or no visibility from the outside if a frame is used. In a further preferred embodiment, the collecting basin is filled with water-absorbing material. The leakage is thereby at the Rotation prevented even better. Water-absorbing material is, for example, water storage granulate. This can be a crosslinked copolymer based on potassium salt. It absorbs up to 300 times its own volume in water. However, sponges or the like are also possible.

In a further preferred embodiment, there is a narrow cavity with, in particular, water-absorbing material on the rear wall with an opening to the collecting basin. A small opening for the release of otherwise accumulating air can be provided. This embodiment offers an additional collecting basin in which even more medium can be taken up from the biofilm for intermediate storage. The water-absorbing material can be designed as before. The mats can also continue beyond the biofilm into the cavity. They too have absorption capacity. The cavity enables lower air opening channels or a lower web, which contributes to a better design. In addition, the space below the tank, if it is attached further up, is unused. This creates a uniformly designed surface. Above all, the housing can then be attached straight for attachment to the wall. Since it is preferably located below the tank, optimal use of space is given. This does not make the housing too deep.

In a further preferred embodiment, straps, in particular cords made of water-transporting material, connect the tank to the interior of the housing via the openings, which in this embodiment have the same size as the straps, and lie there against the distribution mat. In particular, they are immersed in the medium from above in the tank or there is a membrane in the openings which only allows the medium to pass through when there is suction and which is connected to the distribution mat.

The cords or threads can be made of wool, plastic or the like. consist of being wound or braided like wicks. The fibers represent fine channels. The water transport in these is caused by capillary forces (wick effect) and evaporation at the other end. Driving force can also be generated by hydrostatic pressure if the opening is attached to the lower side of the tank. However, since this can lead to too much flow after filling, it is better if the cords are only immersed in the medium and the water is only transported when the evaporation is so high that the capillary forces or evaporation suction outweigh gravity. Alternatively, a membrane can be used, preferably one that is hydrophobic and allows only a little medium to pass through. If the evaporation is high, then the evaporation suction resulting from it can overcome the hydrophobic membrane counter pressure.

In a further preferred embodiment, the tank is flattened and there is a level window on the side facing away from the housing. Due to the flattening, the bioreactor takes up little space when it is attached to the wall. This has advantages in terms of attachment and design. The fill level window enables the fill level to be read off at any time so that the user knows when to top up with new medium through the opening of the tank. Complete transparency of the tank would mean that PAM might also grow there, which is not desirable.

In a further preferred embodiment, there is an irrigation unit, in particular in the form of a drip pipe or hose with openings transversely less than 2 cm above the upper edge of the biofilm or under the distribution mat in the upper area, and a pump, with the medium from the collecting basin being pumped through the irrigation unit is pumped. In this embodiment, the medium reaches the biofilm through an irrigation unit operated by a pump. The irrigation unit can be designed as a drip unit which is attached horizontally over the biofilm or the distribution mat or the growth mat that is not necessarily covered with vegetation at this point. So the mats should protrude so far into the housing or be offset backwards that they can be dripped from above. On the other hand, spraying the biofilm is also conceivable. However, this requires a higher pumping pressure. Also is It is conceivable that an irrigation unit is available below the mats. The diameter of the openings is 0.2 to a few millimeters (corresponds to the diameter of a cannula). It must be prevented that algae grow over these openings. Hence, they shouldn't be enlightened. On the other hand, a cleaning option should be given. For example, a brief, regular pressure increase is to be considered, through which the openings are pushed open again without damaging the biofilm. The pipes or hoses should have a diameter of a few millimeters to centimeters and consist of plastic, for example. A flow on both sides is preferred because the medium meets in the middle and the pressure is greater to flow through the small openings. Due to gravity, the medium runs down the mats and irrigates the biofilm.

In a further preferred embodiment, a collecting edge is provided below the irrigation unit with a gap of less than 1 mm to the biofilm on the growth mat. The collecting edge from e.g. Plastic enables better distribution or collection of the individual drops. Above all, it prevents lines from forming on the biofilm, which would mean an uneven supply. In addition, the collecting edge enables the irrigation unit to be shaded and thus undesired growth of the PAM in the irrigation unit.

In a further preferred embodiment, the transparent material of the front wall is designed as a glass or polymethyl methacrylate pane and there is a groove in each of the side walls and the bottom wall into which the pane is inserted. The ceiling wall is removable and serves as a top closure. To open the housing, the top wall must then be removed and the pane pulled upwards. This enables easy opening. So that the medium does not flow out of the collecting basin when the housing is tilted, if there is no bridge, the disc must be sealed at the bottom. This can e.g. B. can be achieved by a foam rubber on which the disc rests and which is located on the sides. It is also conceivable that the mats are clamped in by the ceiling wall so that no clamping rail or similar device visible in the upper area is necessary. The groove can be implemented, among other things, by attaching a U-profile to the side walls and the bottom wall.

In further preferred embodiments, the side walls and the bottom wall have a groove for inserting the rear wall with biofilm and mats on it or a plane separate from the rear wall with biofilm and mats thereon. These embodiments allow the biofilm to be exchanged easily if a change is necessary. Exchanging the biofilm has to take place under the most sterile conditions possible. Careless movement can also lead to a crack. For the user without these skills, it is easier to just change the solid base of the biofilm. These embodiments thus increase the user friendliness. In these embodiments, too, a detachable ceiling wall can be used as a closure. However, a slot in the ceiling wall is also conceivable through which the level with biofilm is pushed.

In further preferred embodiments, the front side and the rear side have all or some of the curves. In particular, the housing is designed to be cylindrical. For functionality, it is important that the front and back have the same shape. The rectangular shape is based on the distribution of the medium by gravity. However, since capillary forces can also distribute the medium sideways in the distribution mat, another shape is also possible. Also a polygon, a rotated square or e.g. a rhombus are next to round shapes such as circles, ovals, etc. possible.

In further preferred embodiments, the mats are attached by needles, Velcro, a clamping rail, tendons and / or on a grid. A fixation is necessary for vertical use. The attachment should be as little visible as possible and at the same time robust. Needles with a small head are particularly suitable for this. They should be made of rustproof material (steel, treated iron, plastic) and should be as transparent as possible or in a dark green color. At the use of Velcro allows easy removal. The pores of the mats, in particular the waxing mat, enable a good hold. If the Velcro does not adhere to it, you may not need a distribution mat. The use of transparent tendons also has advantages. These can be used for fixing on a grid. The biofilm with the mats can also be attached to a grid without tendons. The grid can be attached to the rear wall.

In further preferred embodiments, a frame is present in front of the front wall or the front wall has a non-transparent surface and the frame or the non-transparent surface are equipped with a photovoltaic system or form one. This means that the area can be used to ensure self-sufficient operation. Power cables are also no longer necessary. Just as solar-powered pocket calculators can be operated with little light, direct operation of a consumer or charging of a battery is conceivable.

In further preferred embodiments, air composition sensors and other sensors are present in or on the housing. Air composition sensors can e.g. determine the humidity or the content of COx, NOx, SOx, ozone, volatile chemicals or ammonia. Another sensor can e.g. be an environmental sensor such as a temperature sensor or a pH sensor. Among other things, the check can take place before and after: at the entrance and exit separately or connected via a common air pipe. The power for the sensors can come from an external source, an integrated mini-PV system and / or battery. Among other things, it can be used for sensors and, if necessary, control of the space on the back below the tank. The measurements are taken at specific times in order to save electricity. In the meantime, the sensors are in sleep mode. This can be controlled by a controller.

In a further preferred embodiment, there is data transmission, in particular a radio connection for transmitting data from the sensors to a receiver. This means that the user can see at any time how the air in the room is composed or other environmental conditions. The data can be sent to a server, a cloud or an app, etc. There is also direct control or communication with e.g. Ventilation devices or sun protection devices possible. The power for the system can come from an external source, an integrated mini-PV system and / or battery.

In a further preferred embodiment, the housing is actively ventilated via the air openings. In particular, a fan is provided in the air openings for this purpose. Active ventilation enables a higher air throughput. Small fans or fans, among other things, can be used for this. They can be inside or outside the case. The power can come from an external power source or from a mini PV system and / or battery.

In a further preferred embodiment, air is introduced into the tank for gassing the medium. This means that substances can be effectively dissolved from the air that is passed through in the medium, which in turn releases them to the biofilm.

In a further preferred embodiment there is a frame or a non-transparent section of the front wall, from which lamps illuminate the interior of the housing and thus the biofilm, which are not visible from the outside. This not only serves to supply the biofilm with light energy and heat, but also enhances the visual appearance of the biofilm. LEDs or the like can be used as lamps. be used. It is also possible to use black light to use the bioluminescence of PAMs, which absorb light in the invisible range but emit it again in the visible range. The power can come from an external power source or from a mini PV system and / or battery.

In a further preferred embodiment, lamps are wholly or partially present below the biofilm or the mats for rear illumination. This not only enables the PAM to be supplied with light energy and heat, it also enables visual highlighting. In particular, certain shapes such as logos etc. can be projected. Economical LEDs can be used as the light source. The power can come from an external power source or from a mini PV system and / or battery. When fully lit, the bioreactor can be used as a wipeable board with the dark colored pens. White pens should be used if there is only partial lighting or no lighting.

In further preferred embodiments, the bioreactor is mounted in the ceiling or floor area of a room, the front wall being reinforced in the floor area. When attached in the ceiling area, the biofilm is e.g. supplied via a hydrophobic membrane which only allows a little medium to pass through and over which the medium is located. It must be ensured that as little medium as possible drips onto the pane. A pump can be used to convey medium to the ceiling via a pipe, with automatic supply being preferred when the fill level is low. Alternatively, the use of rainwater that has collected on the roof is also conceivable. When installed in the floor area, the medium diffuses e.g. from below through the mats to the biofilm or it is applied from above by a spray process or the like. moisturizes. The tank is refilled through an opening or connection pointing upwards. A stable pane with reinforcements if necessary is to be used. The advantage of these embodiments is the use of areas that are otherwise not or only rarely used. In particular, a bioreactor illuminated from the back or the front can be used as a lamp.

Few methods are known in the prior art which are used for air purification by PAM. In JPFI11226351A, actively polluted air is fed to algae. The algae growing in a medium are then harvested, which is energy-intensive, for use as food. EP3368650A1 provides a method and an apparatus for removing air pollutants from the air. A microfluidic chip is used here, which contains a fluid flow path in fluid connection with a surface which comprises a phototrophic organism. Air is brought into contact with this surface and the air pollutant is removed. This solution is also a liquid system, the use of which can be impaired by biofilm formation or the algae must be removed. The mechanical solutions currently available are geared towards individual pollutants and consume energy.

The object of the present invention is to find a solution for efficient and, in particular, low-maintenance air cleaning. With the method presented here, a large number of pollutants can be absorbed with little energy and little maintenance. The object is achieved by claim 21.

In the process, contaminated air then flows into the housing through the air openings in the bioreactor described above and pollutants are absorbed by the stationary, phototrophic biofilm, which is supplied with medium from a tank via openings or an irrigation unit. The now more purified air leaves the housing again through the air openings. The uptake is favored by the moist, large surface on the biofilm, which offers short diffusion paths. PAMs do not absorb their nutrients from the earth and therefore rely on the absorption of nutrients from the air. These are used intracellularly for the maintenance metabolism. The inventors have already shown that not only CO is absorbed, but also NO in the form of nitrate, which forms in the medium and is needed by the PAM for the regeneration of the photosystems.

In the prior art, only a few processes are known in which algae are used to produce valuable materials by means of PAM. In US20100297714A1 phagotrophic algae are used for this purpose. In the process, microorganisms are produced that are eaten by the phagotrophic algae, which in turn are harvested. However, these various steps are very complex. A comparatively complex harvest is also provided for in US8084038B2. The object of the present invention is also a solution for the efficient production of organic valuable substances by means of PAM. For a bio-based economy, raw materials are being sought that can be effectively obtained from atmospheric carbon and allow a move away from petroleum products. The object is achieved by claim 22.

In the disclosed method, the biofilm produces organic valuable substances, which are separated from it and collected by rinsing. It is easy to change media in the bioreactor. It is known that different substances are secreted in different media or air conditions (Akihiro Kato et al.).

PAM have substances in their metabolism that only they can produce. They secrete small molecules like fatty acids, polysaccharides, small peptides and amino acids as well as exotoxins into their environment. Extracellular secretions from Chlorella algae diffuse e.g. through the cell walls and get into the culture medium (Pratt et al.). The algae exudate (chlorellin) had an inhibiting effect on bacteria and algae. Fatty acids are also secreted by Chlorella (Dellagreca et al.). The excretion of a number of amino acids is synchronized with the light cycle of algae photosynthesis (Chang et al.). Bell and Mitchel observed that bacteria of the genus Spirillum were attracted to algae exudates from the diatomaceous algae skeletonema (Bell et al.). Toxic algae secretions including domo acid or brevetoxins occur in harmful algal blooms and threaten other wild animal species (Hallegraeff et al.). On the other hand, these are complicated materials that cannot be produced by chemical synthesis. It was assumed that algae and bacteria release mucilage to protect against ultraviolet radiation (Amsler et al.). In diatoms, the extracellular mucilage contains a complex mixture of proteoglycans and sulfated ones

Polysaccharides (McConville et al.).

PAM secretions can also be used for biofuel production. As in WO2016207338A1, where secreted organic substances such as glycolic acid are used for biogas production. The secretions can come from the uptake of air pollutants and the excess metabolism generated by high radiation.

Further advantages of the present invention are apparent from the detailed description and drawings.

Description of the drawings:

1 is a perspective view of a bioreactor from the front with a front wall.

2 is a perspective view of a bioreactor from the front with the front wall and inserted

Biofilm.

3 is a perspective view of a bioreactor from the rear without a front wall with a visible tank on the rear wall.

4 is an ion chromatographic diagram with nitrite converted from nitrogen dioxide after a retention time of 4 minutes (measured by conductivity in pS)

5 is an ion chromatographic diagram with a reduced content of nitrite converted from nitrogen dioxide after a retention time of 4 minutes (measured by conductivity in pS)

Reference is now made to FIGS. 1-3. Accordingly, the chosen embodiment comprises:

A bioreactor consisting of a rectangular, flat, elongated housing (1), a flat wall (front wall (2)) being glued onto the side walls (4) as a polymethyl methacrylate disk. The housing (1) has air openings in the smallest walls (bottom wall (12) and top wall (13)), visible in FIG. 1. Fig. 2 shows: A static, phototrophic biofilm (5) made of filamentous blue algae has grown on nonwoven fabric (growth mat (6)). This layer lies on a distribution mat (8) as an absorbent fleece. The mats are clamped in the clamping rail (17) at the upper end and lie against the rear wall (7).

Fig. 3 shows: A flat tank (9) is glued to the outside of the rear wall (7) and communicates with the interior of the housing (1) via openings (10) and an opening for refilling (11) and a fill level window (18) has. In the openings there are cords (16) in the form of wool threads, which are connected to one another on the inside of the housing (1), lie against the distribution mat (8) there and transfer medium in the tank to the mats and the biofilm due to evaporation suction ( 5) transport. The fill level can be read through the fill level window (18). As soon as the medium is used up, medium can be refilled through the opening for refilling (11) if necessary. The medium contains the minerals and trace elements necessary for the blue-green algae.

Air flows in from the outside through the openings (10) in the bottom wall (12) and moves over the biofilm (5). The biofilm heats the air, which then flows upwards. The medium with little salts runs in countercurrent. Air pollutants are absorbed. Clean air leaves the air openings (3) in the top wall (13).

The following non-patent literature was cited:

Akihiro et al .: Removal of the product from the culture medium strongly enhances free fatty acid production by genetically engineered Synechococcus elongatus, Biotechnology for Biofuels 10, p. 141.

Amsler et al .: Algal Chemical Ecology, 2008, Springer Berlin / Heidelberg, p. 273.

Bell et al .: Chemotactic and growth responses of marine bacteria to algal extracellular products, 1972 Biol. Bull., Pp. 265-77.

Chang et al .: Excretion of glycolate, mesotartrate and isocitrate lactone by synchronized cultures of Ankistrodesmus braunii, 1970 Plant Physiol. 46, pp. 377-385.

Dellagreca et al .: Fatty Acids Released by Chlorella vulgaris and Their Role in Interference with Pseudokirchneriella subcapitata: Experiments and Modeling, 2010 Journal of Chemical Ecology 36 (3), pp. 339-49.

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Claims

Claims SOL-102 Applicant: Solaga UG Representative: RA Benjamin Herzog

1. Bioreactor consisting of a cuboid, flat, elongated housing (1), one wall of the elongated wide side (front wall (2)) consisting at least partially of transparent material and air openings (3) in the side walls (4) , characterized in that a stationary, phototrophic biofilm (5) on porous material

(Growth mat (6)) in particular nonwoven fabric is grown on a layer of liquid easily distributing material (distribution mat (8)), which rests on or is attached to the inside of the rear wall (7), and a tank (9) with medium for supply of the biofilm (5) are present on the outside of the rear wall (7) or as a protuberance of the housing (1), the tank (9) being in communication with the interior of the housing (1) via openings (10) and an opening for Has refilling (11).

2. Bioreactor according to claim 1, characterized in that air openings (3) are present in the bottom wall (12) and the top wall (13).

3. Bioreactor according to one of the preceding claims, characterized in that a filter or a grid, which has a minimum mesh size of 0.2 mm, is integrated or connected to the air openings (3).

4. Bioreactor according to one of the preceding claims, characterized in that the air openings (3) in particular as channels (14) are extended inward or a web is present on the inside of the bottom wall (12) so that in both cases a collecting basin ( 15) is formed, which is filled in particular with a water-absorbing material.

5. Bioreactor according to one of the preceding claims, characterized in that a narrow cavity with in particular water-absorbing material is present on the rear wall (7) with an opening to the collecting basin (15).

6. Bioreactor according to one of the preceding claims, characterized in that bands, in particular cords (16) made of water-transporting material, which connect the tank (9) to the interior of the housing (1) via the openings (10) in the same size as the bands and lie against the distribution mat (8) there, in particular immerse into the medium in the tank (9) from above, or there is a membrane in the openings (10) that only allows the medium to pass through suction and is in connection with the distribution mat (8) stands.

7. Bioreactor according to one of the preceding claims, characterized in that the tank (9) is flattened and a fill level window is present in the tank (9).

8. Bioreactor according to one of claims 1 to 5, characterized in that an irrigation unit in particular in the form of a drip pipe or drip hose with openings transversely less than 2 cm above the upper edge of the biofilm (5) or below

Distribution mat (8) and a pump are present in the upper area, the medium being pumped through the irrigation unit from the collecting basin (15).

9. Bioreactor according to claim 8, characterized in that a collecting edge is present below the irrigation unit present transversely above the biofilm with a gap of less than 1 mm to the biofilm (5) on the growth mat (6).

10. Bioreactor according to one of the preceding claims, characterized in that the front wall (2) is designed as a glass or polymethyl methacrylate disk, a groove in each of the side walls (4) and the bottom wall (12) into which the disk is from above is inserted, the top wall (13) is removable and serves as an upper lock.

11. Bioreactor according to one of the preceding claims, characterized in that the side walls (4) and the bottom wall (12) separate a groove for the insertion of the rear wall (7) with biofilm (5) and mats on it or one to the rear wall (7) Have level with biofilm (5) and mats on it.

12. Bioreactor according to one of the preceding claims, characterized in that the front side and the rear side are completely or partially rounded, in particular the housing (1) is cylindrical.

13. Bioreactor according to one of the preceding claims, characterized in that the mats are fastened by needles, Velcro, a clamping rail (17), tendons and / or on a grid.

14. Bioreactor according to one of the preceding claims, characterized in that a frame is provided over the front wall (2) or the front wall (2) has a non-transparent surface and the frame or the non-transparent surface are equipped with a photovoltaic system or are themselves made of such exist.

15. Bioreactor according to one of the preceding claims, characterized in that air composition sensors and other sensors are present in or on the housing (1) together with a control unit.

16. Bioreactor according to claim 15, characterized in that there is data transmission, in particular a radio link for transmitting data from the sensors to a receiver.

17. Bioreactor according to one of the preceding claims, characterized in that the housing (1) is actively ventilated via the air openings (3), in particular a fan is present in the air openings (3).

18. Bioreactor according to one of the preceding claims, characterized in that air for gassing the medium is introduced into the tank (9).

19. Bioreactor according to one of the preceding claims, characterized in that a frame is present over the front wall (2) or the front wall (2) has a non-transparent surface, from which lamps are not visible from the outside, the inner area of the housing (1) illuminate.

20. Bioreactor according to one of the preceding claims, characterized in that lamps are provided below the mats over the whole or in part of the surface, which lamps illuminate the biofilm (5) from behind.

21. Bioreactor according to one of the preceding claims, characterized in that it is installed in the ceiling or floor area of a room, wherein the floor area

Front wall (2) is reinforced.

22. A method for air filtering in a bioreactor according to any one of the preceding claims, characterized in that contaminated air flows through the air openings (3) into the housing (1), the air pollutants from the stationary, phototrophic biofilm (5) with the medium a tank (9) is supplied via openings (10) or an irrigation unit,

be taken up and the now more purified air leaves the housing (1) through the air openings (3).

23. The method in a bioreactor according to any one of the preceding claims, characterized in that the biofilm (5) produces organic valuable substances, which are separated from this by rinsing and collected.