DE102019214688A1 - Method and device for purifying room or city air while providing at least one fraction of valuable substances - Google Patents

Abstract

The present invention relates to a method for purifying room or city air while providing at least one valuable material fraction, a valuable material fraction obtainable by the method according to the invention, a device for carrying out the method according to the invention and a system for cleaning room or city air comprising at least two devices for carrying it out of the method according to the invention.

Description

The present invention relates to a method for purifying room or city air while providing at least one valuable material fraction, a valuable material fraction obtainable by the method according to the invention, a device for carrying out the method according to the invention and a system for cleaning room or city air comprising at least two devices for carrying it out of the method according to the invention.

As a result of advancing industrialization worldwide, the steadily growing population, increasing urbanization and increasing motorization of the population, the global emission values and the associated concentration of carbon dioxide (CO ₂ ), nitrogen oxides (NO _x ) and particulate matter have reached worrying and health-endangering levels. _{In particular, particularly high concentrations of CO 2} and NO _{x are} achieved in the air of closed rooms, in cities with heavy traffic and in animal stalls. Despite the known health risks from increased concentrations of NO _x , the limit values set by the WHO (50 mg / m ³ ) and the EU (40 mg / m ³ ) are frequently exceeded. Fine dust particles enter the body through breathing and are associated with an increased risk of cancer, cardiovascular diseases and many other diseases, among other things. Increased CO ₂ concentrations in the air lead to a reduction in gas exchange in the lungs as well as acidification and reduced oxygen saturation of the blood. The primary consequences are fatigue and reduced performance.

In addition to reducing the release of gases that are harmful to the environment and health, such as CO ₂ , NO _x , and fine dust, there is therefore also the need to actively reduce their concentration in the atmosphere, in particular in room and city air.

_{The gases CO 2} and NO _x , which originate primarily from industrial / traffic emissions and human / animal emissions, form central growth factors (C and N sources) for photoautotrophic microorganisms and are used by them for the biosynthesis of organic compounds using light energy. The ability of photoautotrophic microorganisms to be able to form high-energy organic compounds by assimilating emission gases that are harmful to the environment and health has great potential for their use for cleaning particularly polluted air, such as industrial exhaust gases, indoor or city air. The biomass formed as a product of the assimilation of CO ₂ and NO _x can advantageously then be used as a regenerative energy carrier, for example in biogas plants or for the production of biodiesel. In addition to the assimilation of CO ₂ and NO _x and thus a reduction in the concentration of these gases in the air, the photoautotrophic microorganisms enrich the supplied room or city air with molecular oxygen, which is released by the microorganisms as a by-product of photosynthesis.

The present invention is based on the technical problem of cleaning the air in particularly emission-exposed locations, such as in closed rooms and in urban centers, by binding the gases contained in the air, in particular CO ₂ and NO _x , as well as fine dust and at the same time a particularly valuable fraction of valuable substances provide.

The present invention solves the problem on which it is based by means of the subject matter of the independent claims.

1. a) Vorreinigung von Raum- oder Stadtluft mittels Abscheidung von Partikeln mit einer Partikelgröße von mindestens 10 µm zum Erhalt einer vorgereinigten Zuluft,
2. b) Kultivierung mindestens einer Mikroalgenkultur in dem mindestens einen Photobioreaktor in Anwesenheit der vorgereinigten Zuluft und mindestens einer Phosphor-haltigen Komponente bis zum Erreichen einer Schwellen-Biomassekonzentration der Mikroalgenkultur von 6 bis 10 g/L,
3. c) Kultivierung der mindestens einen eine Schwellen-Biomassenkonzentration von 6 bis 10 g/L aufweisenden Mikroalgenkultur unter Phosphor-Limitierung und in Anwesenheit der vorgereinigten Zuluft bis zu einer End-Biomassekonzentration von 9 bis 20 g/L und
4. d) Erhalt einer aufgereinigten Raum- oder Stadtluft und mindestens einer Wertstofffraktion.

The present invention relates in particular to a method for purifying room or city air while providing at least one valuable fraction in a device for purifying room or city air containing at least one photobioreactor, comprising the steps:

1. a) Pre-cleaning of room or city air by separating particles with a particle size of at least 10 µm to obtain pre-cleaned supply air,
2. b) cultivation of at least one microalgae culture in the at least one photobioreactor in the presence of the pre-cleaned supply air and at least one phosphorus-containing component until a threshold biomass concentration of the microalgae culture of 6 to 10 g / L is reached,
3. c) Cultivation of the at least one microalgae culture having a threshold biomass concentration of 6 to 10 g / L with phosphorus limitation and in the presence of the pre-cleaned supply air up to a final biomass concentration of 9 to 20 g / L and
4. d) Preservation of purified room or city air and at least one fraction of recyclable materials.

The method according to the invention is based on the fact that, according to method step a), the room or city air is first pre-cleaned by separating out particles contained in the air, in particular fine dust particles, with a particle size of at least 10 μm. The fine dust particles with a particle size of at least 10 μm can be separated from the room or city air using any means known to those skilled in the art for cleaning gases, for example using special filters. The pre-cleaned supply air is then brought into contact with at least one microalgae culture in at least one photobioreactor, in particular introduced into the at least one microalgae culture, the gases that dissolve in the at least one microalgae culture, in particular CO ₂ and NO _x , from the microalgae as C and N sources can be used for the biosynthesis of high-energy organic compounds. According to step b) of the method, the at least one microalgae culture is cultivated in the at least one photobioreactor in the presence of the pre-cleaned air, additionally in the presence of at least one phosphorus-containing component that serves as a phosphorus source for the growth of the at least one microalgae culture. The algae contained in the at least one microalgae culture form in the presence of light, in particular natural sunlight or artificial light, and with absorption of carbon and nitrogen from the CO ₂ and NO _x contained in the pre-cleaned supply air and with absorption of phosphorus from the at least one phosphor -containing component photoautotrophic biomass. The at least one microalgae culture is cultivated under these conditions until a biomass concentration, the so-called threshold biomass concentration, of 6 to 10 g / L is reached. When the threshold biomass concentration is reached, the phosphorus in the at least one microalgae culture is limited in the method according to the invention. This can be achieved, for example, in that when the threshold biomass concentration is reached, the at least one phosphorus-containing component is no longer added or an originally provided amount of phosphorus-containing component is consumed when the threshold biomass concentration is reached. In the absence of phosphorus or with a limitation of the phosphorus contained in the microalgae culture, the microalgae in the at least one microalgae culture use the light energy primarily to accumulate storage materials, in particular carbohydrates and lipids, and / or to form secondary metabolites. According to step c) of the method according to the invention, the at least one microalgae culture with a threshold biomass concentration of 6 to 10 g / L is cultivated with phosphorus limitation and in the presence of the pre-cleaned supply air up to a final biomass concentration of 9 to 20 g / L, so that when the final biomass concentration according to step d) is reached, in addition to the purified room or city air formed in the course of the method according to the invention, in particular during steps b) and c), and released again into the environment, at least one fraction of valuable substances is also obtained.

According to a preferred embodiment of the present invention, the at least one photobioreactor is an airlift photobioreactor. The at least one airlift photobioreactor is particularly preferably a plate reactor.

The preferably used airlift photobioreactors are distinguished in particular by the fact that no mechanical agitators and no pumps are used to circulate the liquid contained in the reactor, in particular the at least one microalgae culture contained in the reactor. Circulation within the reactor takes place by introducing gas into the lower area of the reactor, the gas introduced into the reactor, which is preferably distributed in fine bubbles, through the liquid in the reactor, in particular the at least one microalgae culture in the reactor, in the direction of the head side of the reactor rises. The rising, preferably finely distributed gas bubbles lead on the one hand to a phase transition of the gases introduced, in particular CO ₂ and NO _x , from the gas phase to the liquid phase, in particular to the culture medium of the at least one microalgae culture, and on the other hand to the circulation of the Ensure reactor content.

The at least one photobioreactor, in particular the at least one airlift photobioreactor, is particularly preferably one in the EP 1 326 959 B1 described photobioreactor, particularly preferably a photobioreactor according to claim 1 of EP 1 326 959 B1 , in particular a bioreactor for the cultivation of microorganisms, with a light-permeable housing through which gas bubbles formed by gas entry flow in one direction of flow and in which a flow-guiding device is arranged, which is characterized in that the flow-guiding device comprises at least two septa that transversely are arranged to the direction of flow.

In a preferred embodiment of the present invention, air to be cleaned is supplied by means of at least one fan.

According to a further preferred embodiment, the air to be cleaned is supplied by means of at least one compressor.

The use of at least one fan for the supply of air to be cleaned has the advantage that it has a significantly lower energy consumption than compressors and the method according to the invention can thus be carried out much more economically when using at least one fan for the supply of air to be cleaned than with Use of at least one compressor would be the case. For the implementation of the method according to the invention using at least one airlift photobioreactor, the resistance of the water column in the at least one is decisive for the choice of a suitable compression unit, in particular for the choice between at least one fan or at least one compressor for the supply of air to be cleaned an airlift photobioreactor has to be overcome. In the method according to the invention, the height of the water column to be overcome is particularly preferably selected such that the air to be cleaned can be supplied by means of at least one fan.

In a further preferred embodiment of the present invention, pre-cleaned air is continuously introduced into the at least one photobioreactor containing at least one microalgae culture.

According to a further preferred embodiment of the present invention, pre-cleaned air is introduced discontinuously, in particular batchwise, into the at least one photobioreactor containing at least one microalgae culture.

In a preferred embodiment, the at least one microalgae culture is cultivated in the at least one photobioreactor in the presence of the pre-cleaned supply air according to steps b) and c) with fine-bubble introduction, in particular continuous fine-bubble introduction, of the pre-cleaned air into the at least one microalgae culture having the at least one Photobioreactor. Porous gas distributors, in particular porous gas distributors made of plastic or porous ceramic or metallic gas distributors, are particularly preferably used for introducing the pre-cleaned air in fine bubbles. The fine-bubble introduction, in particular continuous fine-bubble introduction, of the pre-cleaned air into the at least one photobioreactor containing the at least one microalgae culture leads, through the large surface area of the fine gas bubbles and the associated large contact area between gas and liquid phase, advantageously to an efficient mass transfer of the pre-cleaned air Gases contained in supply air, in particular CO ₂ and NO _x , from the gas phase into the liquid phase.

In a preferred embodiment of the present invention, the at least one microalgae culture is cultivated in the at least one photobioreactor in the presence of the pre-cleaned supply air according to steps b) and c), preferably according to step b), preferably according to step c), with a gas throughput, in particular at a constant gas throughput of 0.05 to 1.0 vvm (vol. air / vol. culture medium / min), preferably 0.1 to 0.9 vvm, preferably 0.1 to 0.85 vvm, preferably 0.1 up to 0.8 vvm, preferably 0.15 to 0.75 vvm, preferably 0.15 to 0.7 vvm, preferably 0.2 to 0.65 vvm, preferably 0.2 to 0.6 vvm, preferably 0.25 up to 0.55 vvm, preferably 0.25 to 0.5 vvm, preferably 0.3 to 0.45 vvm, preferably 0.3 to 0.4 vvm.

The at least one microalgae culture is particularly preferably cultivated in the at least one photobioreactor in the presence of the pre-cleaned supply air according to steps b) and c), preferably according to step b), preferably according to step c), at a gas throughput, in particular at a constant gas throughput, of at least 0.05 vvm (vol. air / vol. culture medium / min), preferably at least 0.1 vvm, preferably at least 0.15 vvm, preferably at least 0.2 vvm, preferably at least 0.25 vvm, preferably at least 0, 3 vvm.

More preferably, the at least one microalgae culture is cultivated in the at least one photobioreactor in the presence of the pre-cleaned supply air according to steps b) and c), preferably according to step b), preferably according to step c), at a gas throughput, in particular at a constant gas throughput, of at most 2 vvm (vol. air / vol. culture medium / min), preferably at most 1.5 vvm, preferably at most 1 vvm, preferably at most 0.9 vvm, preferably at most 0.8 vvm, preferably at most 0.7 vvm, preferably at most 0.6 vvm, preferably at most 0.5 vvm.

In a further preferred embodiment of the present invention, the at least one microalgae culture is cultivated in the at least one photobioreactor in the presence of the pre-cleaned supply air according to steps b) and c), preferably according to step b), preferably according to step c), at a constant or variable gas throughput.

The gas throughput is particularly preferably varied stepwise or continuously in the course of the process. More preferably, the gas flow rate is varied as a function of the biomass concentration contained in the at least one photobioreactor. According to this embodiment, if the biomass concentration is initially low in the at least one photobioreactor, a low, non-limiting gas throughput is also selected and this is increased gradually or continuously with increasing biomass concentration in the at least one photobioreactor.

More preferably, the pre-cleaned air is passed through the at least one photobioreactor containing at least one microalgae culture at least twice, preferably at least three times, preferably at least four times for the particularly efficient reduction of the gases contained therein, in particular CO ₂ and NO _x. For the particularly efficient reduction of the gases contained therein, in particular CO ₂ and NO _x , the pre-cleaned air is particularly preferably passed through the photobioreactor containing at least one microalgae culture until a specified final cleaning concentration for CO ₂ and / or NO _x for the room or city air is reached.

In a preferred embodiment of the present invention, the at least one microalgae culture is cultivated in the at least one photobioreactor in the presence of the pre-cleaned supply air and at least one phosphorus-containing component according to step b) until a threshold biomass concentration of the microalgae culture of 6 to 9 g / L, preferably 6 to 8 g / L, preferably 6 to 7 g / L, preferably 7 to 10 g / L, preferably 7 to 9 g / L, preferably 7 to 8 g / L.

The at least one microalgae culture is particularly preferably cultivated in the at least one photobioreactor in the presence of the pre-cleaned supply air and at least one phosphorus-containing component according to step b) until a threshold biomass concentration of the microalgae culture of at most 10 g / L, preferably at most 9, is reached. 5 g / L, preferably at most 9 g / L, preferably at most 8.5 g / L, preferably at most 8 g / L, preferably at most 7.5 g / L, preferably at most 7 g / L, preferably at most 6.5 g / L, preferably at most 6 g / L.

According to a further preferred embodiment of the present invention, the at least one threshold biomass concentration, in particular a threshold biomass concentration of 6 to 10 g / L, preferably 6 to 9 g / L, preferably 6 to 8 g / L, is preferably cultivated 6 to 7 g / L, preferably 7 to 10 g / L, preferably 7 to 9 g / L, preferably 7 to 8 g / L, preferably at most 10 g / L, preferably at most 9.5 g / L, preferably at most 9 g / L, preferably at most 8.5 g / L, preferably at most 8 g / L, preferably at most 7.5 g / L, preferably at most 7 g / L, preferably at most 6.5 g / L, preferably at most 6 g / L, containing microalgae culture with phosphorus limitation and in the presence of the pre-cleaned supply air according to step c) up to a final biomass concentration of 9.5 to 20 g / L, preferably 10 to 20 g / L, preferably 10.5 to 20 g / L, preferably 11 to 20 g / L, preferably 11.5 to 20 g / L, preferably 12 to 20 g / L, preferably 12.5 to 20 g / L, preferably 13 to 20 g / L, preferably 13.5 bi s 20 g / L, preferably 14 to 20 g / L, preferably 14.5 to 20 g / L, preferably 15 to 20 g / L.

The at least one threshold biomass concentration is preferably cultivated, in particular the threshold biomass concentration of 6 to 10 g / L, preferably 6 to 9 g / L, preferably 6 to 8 g / L, preferably 6 to 7 g / L, preferably 7 to 10 g / L, preferably 7 to 9 g / L, preferably 7 to 8 g / L, preferably at most 10 g / L, preferably at most 9.5 g / L, preferably at most 9 g / L, preferably at most 8 , 5 g / L, preferably at most 8 g / L, preferably at most 7.5 g / L, preferably at most 7 g / L, preferably at most 6.5 g / L, preferably at most 6 g / L, microalgae culture under phosphorus Limitation and in the presence of the pre-cleaned supply air according to step c) up to a final biomass concentration of at least 9 g / L, preferably at least 9.5 g / L, preferably at least 10 g / L, preferably at least 10.5 g / L, preferred at least 11 g / L, preferably at least 11.5 g / L, preferably at least 12 g / L, preferably at least 12.5 g / L, preferably at least 13 g / L, preferably at least 13 , 5 g / L, preferably at least 14 g / L, preferably at least 14.5 g / L, preferably at least 15 g / L.

The cultivation of the at least one threshold biomass concentration, in particular the threshold biomass concentration of 6 to 10 g / L, preferably 6 to 9 g / L, preferably 6 to 8 g / L, preferably 6 to 7 g / L, is particularly preferred , preferably 7 to 10 g / L, preferably 7 to 9 g / L, preferably 7 to 8 g / L, preferably at most 10 g / L, preferably at most 9.5 g / L, preferably at most 9 g / L, preferably at most 8.5 g / L, preferably at most 8 g / L, preferably at most 7.5 g / L, preferably at most 7 g / L, preferably at most 6.5 g / L, preferably at most 6 g / L, microalgae culture under phosphorus -Limitation and in the presence of the pre-cleaned supply air according to step c) up to a final biomass concentration of at most 30 g / L, preferably at most 28 g / L, preferably at most 26 g / L, preferably at most 24 g / L, preferred at most 22 g / L, preferably at most 20 g / L, preferably at most 18 g / L, preferably at most 16 g / L, preferably at most 14 g / L, preferably at most 12 g / L.

In a preferred embodiment of the present invention, the phosphorus limitation takes place in step c) by consuming a phosphorus depot added to the culture medium of at least one phosphorus-containing component, preferably a readily soluble phosphorus-containing component that is sufficiently concentrated to achieve a Allow threshold biomass concentration and no growth inhibition caused or a poorly soluble phosphorus-containing component, for example magnesium ammonium phosphate (MAP). According to these embodiments, a previously calculated amount of a phosphorus depot comprising at least one phosphorus-containing component, preferably at least one readily soluble phosphorus-containing component or at least one sparingly soluble phosphorus-containing component, can be added to the culture medium at the beginning of the method Achieving a desired biomass concentration is consumed, so that from this point in time growth is inhibited by phosphorus limitation.

In a further embodiment of the present invention, the phosphorus limitation is achieved when a desired biomass concentration is reached by terminating a continuous or stepwise addition of at least one phosphorus-containing component.

In a preferred embodiment of the present invention, the at least one microalgae culture is cultivated in step c) in the presence of a growth-inhibiting amount of a substance. Due to the presence of a growth-inhibiting amount of a substance, the light energy is increasingly used by the microalgae culture for the biosynthesis and accumulation of storage substances and / or secondary metabolites. The growth-inhibiting amount of a substance can be a growth-inhibiting amount formed during the growth of the microalgae culture, in particular during the cultivation of the at least one microalgae culture in the at least one photobioreactor in the presence of the pre-cleaned supply air and a phosphorus-containing component according to step b) act of a substance. The growth-inhibiting amount of a substance can also be an amount of a certain substance added when the threshold biomass concentration of the microalgae culture of 6 to 10 g / L is reached, which inhibits the growth of the microalgae culture. In a further embodiment of the present invention, the substance present in a growth-inhibiting amount is a substance that accumulates in the at least one microalgae culture by introducing the pre-cleaned air, in particular by continuously introducing the pre-cleaned air.

According to a preferred embodiment of the present invention, the at least one microalgae culture is cultivated in the at least one photobioreactor in steps b) and c), preferably in step b), preferably in step c), with switching on artificial light, in particular LED light .

In an alternative embodiment of the present invention, the at least one microalgae culture is cultivated in the at least one photobioreactor in steps b) and c), preferably in step b), preferably in step c), exclusively in the presence of artificial light, in particular LED light. Light.

By using artificial light, in particular by switching on artificial light, it is advantageously possible to compensate for an insufficient supply of the at least one microalgae culture with light, in particular an insufficient supply of the at least one microalgae culture with natural sunlight. In addition, the artificial light can ensure that the at least one microalgae culture is supplied with the light energy required for photosynthesis, which is independent of the time of day and season, in particular all day, in particular all year round. It is crucial for the choice of light intensity that it is high enough on the one hand to ensure growth and / or the biosynthesis and accumulation of storage substances and / or secondary metabolites, but on the other hand not so high that it is inhibited on growth which affects at least one microalgae culture. When choosing the light source, in particular the intensity of the selected light source, it should be noted that too high a light intensity can lead to the destruction of the chlorophyll contained in the microalgae and essential for photosynthesis. When choosing a suitable light source, in particular a suitable light intensity, different factors such as layer thickness, biomass concentration, gas throughput, type and composition of the microalgae culture used, etc. play a role. When using artificial light, the intensity and the wavelength of the light acting on the at least one microalgae culture can be selected and / or regulated in a simple manner. In the case of intense natural sunlight, a possible inhibition of microalgae growth can be achieved, for example, by a suitable choice of used microalgae culture, the biomass concentration and the gas throughput or through the use of filters.

In a further preferred embodiment of the present invention it is provided that the room or city air purified in steps a) to d) before leaving the at least one photobioreactor to a humidity of 40 to 60%, preferably 42 to 58%, preferably 44 to 56%, preferably 46 to 54%, preferably 48 to 52%, is set. The water recovered when the atmospheric humidity is adjusted is particularly preferably returned to the at least one photobioreactor.

The room or city air purified in steps a) to d) preferably passes through at least one hygiene filter before it leaves the at least one photobioreactor.

In a preferred embodiment of the present invention, the at least one microalgae culture to be cultivated in step b) in the at least one photobioreactor has an initial biomass concentration of 0.2 g / L to 4 g / L, preferably 0.2 g / L to 3, 5 g / L, preferably 0.2 g / L to 3 g / L, preferably 0.2 g / L to 2.5 g / L, preferably 0.2 g / L to 2 g / L, preferably 0.2 g / L to 1.5 g / L, preferably 0.2 g / L to 1 g / L, preferably 0.5 g / L to 4 g / L, preferably 0.5 g / L to 3.5 g / L, preferably 0.5 g / L to 3 g / L, preferably 0.5 g / L to 2.5 g / L, preferably 0.5 g / L to 2 g / L, preferably 0.5 g / L up to 1.5 g / L, preferably 0.5 to 1 g / L, preferably 1 g / L to 4 g / L, preferably 1 g / L to 3.5 g / L, preferably 1 g / L to 3 g / L, preferably 1 g / L to 2.5 g / L, preferably 1 g / L to 2 g / L, preferably 1 g / L to 1.5 g / L.

The at least one microalgae culture to be cultivated in step b) in the at least one photobioreactor preferably has an initial biomass concentration of at least 0.2 g / L, preferably at least 0.5 g / L, preferably at least 1 g / L, preferably at least 1, 5 g / L, preferably at least 2 g / L.

According to a further preferred embodiment, the at least one microalgae culture to be cultivated in step b) in the at least one photobioreactor has an initial biomass concentration of at most 4 g / L, preferably at most 3.5 g / L, preferably at most 3 g / L, preferably at most 2.5 g / L, preferably at most 2 g / L, preferably at most 1.5 g / L, preferably at most 1 g / L, preferably at most 0.5 g / L.

The at least one microalgae culture is preferably a unialgal culture, preferably an axenic culture. Particularly preferred is the unialgal culture, preferably axenic culture, preferably selected from the group consisting of: Chlorella, Chlamydomonas, Phaeodactylum, Nannochloropsis, Haematococcus, Diacronema, Synechococcus, Thermosynechococcus, Synechocystis, Porphyridium, Microchloropsis, Scenedesmus and Dunechococcus.

In a further preferred embodiment of the present invention, the at least one microalgae culture is a mixed culture. The mixed culture particularly preferably comprises at least two, preferably at least three, preferably at least four, algae genera selected from the group consisting of: Chlorella, Chlamydomonas, Phaeodactylum, Nannochloropsis, Haematococcus, Diacronema, Synechococcus, Thermosynechococcus, Synechocystis, Porphyridium, Microchloropsis and Dunedesmus, Scenedesmusella.

In a preferred embodiment, the mixed culture comprises two, preferably at most three, preferably at most four, preferably at most five, algae genera selected from the group consisting of: Chlorella, Chlamydomonas, Phaeodactylum, Nannochloropsis, Haemtoacoccus, Diacronema, Synechococcus, Thermosynechococcus, Synechocystis, Porchlorphyridium, , Scenedesmus and Dunaliella.

In a preferred embodiment of the present invention, at least one photobioreactor of the device is exchangeable. The at least one microalgae culture is particularly preferably harvested after step d) by exchanging at least one photobioreactor of the device.

As at least one photobioreactor of the device can be exchanged, the method according to the invention can be operated continuously, preferably quasi-continuously, when there are at least two photobioreactors. In particular, when the final biomass concentration is reached, one or more photobioreactors of the device, including the at least one microalgae culture contained therein, can be replaced and the one or more photobioreactors can be replaced by one or more photobioreactors containing new culture medium, so that on the one hand the harvest of the end -Biomass concentration exhibiting microalgae cultures takes place and on the other hand through the use one or more photobioreactors containing new culture medium, a dilution of the biomass concentration in the overall system takes place. The exchange of at least one photobioreactor can preferably take place during operation of the device for cleaning room or city air, the method continuing during the exchange of at least one photobioreactor in at least one remaining photobioreactor of the device.

The present invention also relates to a fraction of valuable substances obtainable, preferably obtained, from the process according to the invention.

The valuable material fraction obtainable, preferably obtained, from the process according to the invention is characterized in particular by its high content of storage substances, in particular of carbohydrates and lipids, and / or secondary metabolites.

The high content of the valuable fraction of storage materials and / or secondary metabolites is due in particular to the fact that in the method according to the invention, when a threshold biomass concentration of the microalgae culture is reached, phosphorus is limited, which means that the microalgae prefer to use light energy for biosynthesis and accumulation of storage materials, in particular of carbohydrates and lipids, and / or secondary metabolites. A special feature of the valuable fraction obtained by limiting phosphorus in step c) in step d) is, in addition to the higher content of energy-rich storage substances and / or secondary metabolites compared to conventional methods, the fact that the accumulated storage substances, in particular carbohydrates and lipids, have a have a low content of nitrogen, sulfur and phosphorus, are particularly preferably free of nitrogen, sulfur and phosphorus.

1. i) mindestens einen Einlass für Raum- oder Stadtluft,
2. ii) mindestens eine Vorrichtung zur Abscheidung von Partikeln mit einer Partikelgröße von mindestens 10 µm,
3. iii) mindestens einen Photobioreaktor und
4. iv) mindestens einen Auslass für aufreinigte Raum- oder Stadtluft, wobei der mindestens eine Photobioreaktor der Vorrichtung austauschbar ist.

The present invention also relates to a device for carrying out the method according to the invention, comprising

1. i) at least one inlet for room or city air,
2. ii) at least one device for separating particles with a particle size of at least 10 µm,
3. iii) at least one photobioreactor and
4. iv) at least one outlet for purified room or city air, the at least one photobioreactor of the device being exchangeable.

According to a preferred embodiment of the present invention, the at least one device for separating particles with a particle size of at least 10 μm is a filter.

In a preferred embodiment of the present invention, the device comprises at least two photobioreactors, preferably at least three photobioreactors, preferably at least four photobioreactors, preferably at least five photobioreactors.

The device according to the invention particularly preferably comprises at least two photobioreactors, preferably at least three photobioreactors, preferably at least four photobioreactors, preferably at least five photobioreactors, of which at least one photobioreactor is exchangeable.

In a further preferred embodiment of the present invention, the device according to the invention comprises at least two photobioreactors, preferably at least three Photobioreactors, preferably at least four photobioreactors, preferably at least five photobioreactors, which are arranged parallel to one another.

The at least two photobioreactors, preferably at least three photobioreactors, preferably at least four photobioreactors, preferably at least five photobioreactors, which are preferably arranged parallel to one another, are preferably connected to one another. The at least two photobioreactors, preferably at least three photobioreactors, preferably at least four photobioreactors, preferably at least five photobioreactors, are particularly preferably in liquid contact with one another. According to this embodiment, the microalgae cultures contained in the at least two photobioreactors, preferably at least three photobioreactors, preferably at least four photobioreactors, preferably at least five photobioreactors, circulate between the at least two photobioreactors, preferably at least three photobioreactors, preferably at least four photobioreactors, preferably at least five photobioreactors .

In connection with the present invention, at least two photobioreactors, preferably at least three photobioreactors, preferably at least four photobioreactors, preferably at least five photobioreactors, of a device according to the invention, of a device according to the invention, are also referred to as a “stack”.

In a preferred embodiment, the device according to the invention comprises at least two, preferably at least three, preferably at least four, preferably at least five, preferably arranged parallel to one another, preferably connected to one another, photobioreactors, the individual reactors having pre-cleaned supply air, in particular pre-cleaned room or city air, via at least one Fan or at least one compressor, preferably via at least one fan, preferably via at least one compressor, is supplied. Mixing of the liquid in the at least two, preferably at least three, preferably at least four, preferably at least five, preferably arranged parallel to one another, interconnected photobioreactors, in particular the at least one microalgae culture, can take place, for example, via a common return line, into which in each case from Lines emerge from the upper area of the individual reactors. According to a preferred embodiment, lines opening into the lower liquid region of the respective individual reactors arise from the common return line.

According to a further preferred embodiment, the device comprises at least one artificial light source. The at least one artificial light source is particularly preferably an LED lamp.

In a preferred embodiment of the present invention, the device according to the invention comprises at least two, preferably at least three, preferably at least four, preferably at least five, preferably arranged parallel to one another, preferably connected to one another, photobioreactors, an artificial light source being arranged between each two photobioreactors.

In a preferred embodiment of the present invention, the device has at least one anti-freeze device. The presence of at least one anti-freeze protection can be of advantage especially when using the device according to the invention for cleaning city air and thus possibly with exposure to temperatures below 0 ° C depending on the year and / or time of day, so that preferably all-year and / or all-day operation of the device can be guaranteed. In a particular embodiment, the at least one anti-freeze protection is a roll film surrounding the at least one photobioreactor, in particular a motor-driven roll film. Particularly preferably, by surrounding the at least one photobioreactor of the device according to the invention, in particular the entire device according to the invention, with roll films in combination with the heat generated by at least one artificial light source, in particular LED light source, freezing of the liquid in the at least one photobioreactor is prevented.

In a further preferred embodiment of the present invention, the device according to the invention has at least one overheating protection. The presence of at least one overheating protection can be of advantage in particular when using the device according to the invention for cleaning city air and thus in the event of the possible occurrence of high temperatures, in particular temperatures of> 35 ° C, which impair the growth of the at least one microalgae culture, so that a preferably year-round and / or all-day operation of the device can be guaranteed. In a particular embodiment, the at least one overheating protection is a roll film surrounding the at least one photobioreactor, in particular a motorized roll film. By surrounding the at least one photobioreactor of the device according to the invention, in particular the entire device according to the invention with rolled films, in particular rolled films with IR protection, overheating of the liquid in the at least one photobioreactor, in particular a temperature impairing growth, in particular a temperature of > 35 ° C, prevented by intense natural sunlight.

The present invention also relates to a system for purifying room or city air while providing at least one valuable fraction, comprising at least two devices according to the invention, the at least two devices according to the invention being arranged one above the other in the system and each rotated relative to one another.

In a preferred embodiment of the present invention, the at least two devices according to the invention are arranged one above the other in the system and each rotated by 60 to 120 °, preferably 70 to 110 °, preferably 80 to 100 °, preferably 85 to 95 °, preferably 90 ° .

The at least two devices according to the invention are particularly preferred in the system one above the other and each by at least 10 °, preferably at least 20 °, preferably by at least 30 °, preferably by at least 45 °, preferably by at least 60 °, preferably by at least 75 °, preferably by at least 80 °, preferably arranged rotated by at least 90 ° with respect to one another.

The arrangement of the at least two devices according to the invention one above the other and, associated with this, a mainly vertical extension of the system advantageously enables a space-saving operation of the system, which is preferred or even required, particularly in cities due to the often limited space available. Furthermore, by arranging the at least two devices according to the invention one above the other and each rotated relative to one another, an efficient use of natural sunlight can be achieved over the entire course of the day.

The statements made above and described embodiments in connection with the method according to the invention also apply mutatis mutandis to the device according to the invention for carrying out the method according to the invention and the system according to the invention for purifying room or city air and vice versa.

In connection with the present invention, the term “photobioreactor” denotes a bioreactor or fermenter which is suitable for the cultivation of photoautotrophic organisms, in particular photoautotrophic microalgae. A special feature of a photobioreactor according to the invention is the permeability of the reactor, in particular the reactor walls, to light which can be used for photosynthesis by the photoautotrophic organisms contained in the photobioreactor.

In connection with the present invention, the term “valuable material fraction” is understood to mean a group of substances which is characterized by being of particular value for a specific use. In particular, the term denotes the biomass of microalgae formed in the process according to the invention, as well as the energy-rich organic compounds formed by them, in particular storage materials that are available as regenerable energy sources, for example for biogas plants or for the production of biodiesel, after the photoautotrophic microalgae are harvested. The special value of the valuable fraction formed with the process according to the invention results in particular from the presence of accumulated storage materials, in particular carbohydrates and lipids, which have a high energy density and preferably have a low content of nitrogen, sulfur and phosphorus, particularly preferably free of nitrogen , Sulfur and phosphorus are. The high proportion of these storage materials in the biomass also makes it easier to use them economically. Secondary metabolites, which can also be formed while growth is limited by phosphorus, are often pharmacologically interesting compounds which, for example, can prevent competing organisms from growing. The value of such substances can significantly exceed the value of the storage substances in the valuable fraction.

In connection with the present invention, the term “initial biomass concentration” denotes the concentration of microalgae present in the at least one microalgae culture in the at least one photobioreactor at the beginning of the method. The choice of a suitable “initial biomass concentration” depends on various factors, such as the type of microalgae used, temperature, light intensity, and CO ₂ and NO _x concentration.

According to the invention, the term “threshold biomass concentration” denotes a concentration of microalgae in the at least one photobioreactor achieved during cultivation in the at least one photobioreactor according to step b), from which growth inhibition by phosphorus limitation and / or by the presence of a growth-inhibiting concentration of a substance takes place.

In connection with the present invention, a “final biomass concentration” denotes the concentration of microalgae in the at least one photobioreactor up to which the at least one microalgae culture is cultivated with phosphorus limitation and in the presence of the pre-cleaned supply air according to step c). When the “final biomass concentration” is reached, at least some of the microalgae of the at least one microalgae culture are preferably harvested.

In connection with the present invention, the term “unialgal culture” denotes a microalgae culture in which only one type of algae occurs. The term therefore does not exclude the fact that the microalgae culture contains other organisms, such as bacteria, in addition to the type of algae concerned.

In connection with the present invention, the term “axenic culture” is understood to mean a pure culture. The term accordingly denotes a microalgae culture in which only a single type of algae occurs, with no other organisms, in particular no bacteria, being present in the culture besides the type of algae in question.

In connection with the present invention, the terms “comprising” and “having” are understood to mean that, in addition to the elements explicitly covered by these terms, further elements that are not explicitly mentioned can be added. In connection with the present invention, these terms are also understood to mean that only the explicitly named elements are included and no further elements are present. In this particular embodiment, the meaning of the terms “comprising” and “having” is synonymous with the term “consisting of”. In addition, the terms “comprising” and “having” also include compositions which, in addition to the explicitly named elements, also contain other non-named elements, but which are functionally and qualitatively subordinate in nature. In this embodiment, the terms “comprising” and “having” are synonymous with the term “consisting essentially of”.

In connection with the present invention, the term “and / or” is understood to mean that all members of a group which are connected by the term “and / or” are disclosed both as alternatives to one another and also cumulatively with one another in any combination. For the expression "A, B and / or C" this means that the following disclosure content is to be understood: a) A or B or C or b) (A and B) or c) (A and C) or d) ( B and C) or e) (A and B and C).

Further embodiments of the present invention are the subject of the dependent claims.

The present invention is explained in more detail below using an example and the figures.

• 1 zwei schematische Darstellungen einer erfindungsgemäßen Vorrichtung zur Aufreinigung von Raum- oder Stadtluft (1) mit zur Veranschaulichung transparent dargestelltem Gehäuse (11) (1A) und mit Gehäuse (11) (1B). Bei der dargestellte Ausführungsform der Vorrichtung zur Aufreinigung von Raum- oder Stadtluft (1) tritt zu reinigende Luft über einen Lufteinlass (2) in die Vorrichtung ein und passiert zur Vorreinigung der Zuluft zunächst einen Grobfilter (3) und einen Sterilfilter (4). Im unteren Bereich der Vorrichtung sind diverse Maschinenkomponenten und die Maschinensteuerung (5) untergebracht. Die vorgereinigte Zuluft wird über einen Luftverteiler (6) den parallel zueinander angeordneten Photobioreaktoren mit LED-Beleuchtung (7) zugeführt. Nach Durchströmen der Photobioreaktoren mit LED-Beleuchtung (7) wird die aufgereinigte Luft (Abluft) über Luftrückführungen (8) einer Vorrichtung zur Luftaufbereitung und -kondensation (9) zugeführt und die aufbereitete, gereinigte und mit Sauerstoff angereicherte Abluft über einen Luftauslass (10) wieder freigesetzt.
• 2 zwei perspektivische schematische Darstellungen einer erfindungsgemäßen Anlage zur Aufreinigung von Raum- oder Stadtluft (100) umfassend drei übereinander und jeweils um 90° verdreht zueinander angeordnete erfindungsgemäße Vorrichtungen zur Aufreinigung von Raum- oder Stadtluft (104, 105, 106). In Betrieb der dargestellten Ausführungsform der erfindungsgemäßen Anlage (100) wird den drei erfindungsgemäßen Vorrichtungen (104, 105, 106) über einen Lufteinlass (101) und ein vertikal angeordnetes Saugrohr mit Grobfilter (102) zu reinigende Luft zugeführt. Nach dem Durchströmen der jeweils fünf parallel zueinander angeordneten Photobioreaktoren der drei erfindungsgemäßen Vorrichtungen (104, 105, 106) wird die gereinigte und mit Sauerstoff angereicherte Luft über eine Luftrückführung (107) und einen Luftauslass (108) wieder freigesetzt. In der Luftrückführung (107) erfolgt bevorzugt eine Kondensation des in der Abluft enthaltenen Wassers, das anschließend in die Photobioreaktoren zurückgeführt wird. Im unteren Bereich der dargestellten Anlage (100) sind die Maschinenkomponenten und die Maschinensteuerung (103) der Anlage (100) untergebracht.

It shows

• 1 two schematic representations of a device according to the invention for cleaning room or city air ( 1 ) with the housing shown as transparent for illustration ( 11 ) ( 1A) and with housing ( 11 ) ( 1B) . In the illustrated embodiment of the device for cleaning room or city air ( 1 ) air to be cleaned enters via an air inlet ( 2 ) into the device and first passes through a coarse filter ( 3rd ) and a sterile filter ( 4th ). In the lower area of the device are various machine components and the machine control ( 5 ) housed. The pre-cleaned supply air is distributed via an air distributor ( 6th ) the parallel arranged photobioreactors with LED lighting ( 7th ) supplied. After flowing through the photobioreactors with LED lighting ( 7th ) the purified air (exhaust air) is returned via air recirculation ( 8th ) a device for air conditioning and condensation (9) and the conditioned, cleaned and oxygen-enriched exhaust air via an air outlet ( 10 ) released again.
• 2 two perspective schematic representations of a system according to the invention for the purification of room or city air ( 100 ) comprising three devices according to the invention for the purification of room or city air arranged one above the other and rotated by 90 ° to each other ( 104 , 105 , 106 ). In operation of the illustrated embodiment of the system according to the invention ( 100 ) is the three devices according to the invention ( 104 , 105 , 106 ) via an air inlet ( 101 ) and a vertically arranged suction pipe with a coarse filter ( 102 ) air to be cleaned is supplied. After flowing through the five parallel photobioreactors of the three devices according to the invention ( 104 , 105 , 106 ) the cleaned and oxygen-enriched air is returned via an air return ( 107 ) and an air outlet ( 108 ) released again. In the air return ( 107 ) there is preferably a condensation of the water contained in the exhaust air, which is then returned to the photobioreactors. In the lower area of the system shown ( 100 ) are the machine components and the machine control ( 103 ) the plant ( 100 ) housed.

List of reference symbols

1

Device for cleaning room or city air

2

Air inlet

3

Coarse filter

4th

Sterile filter

5

Machine components and machine control

6th

Air distributor

7th

Photobioreactors with LED lighting

8th

Air recirculation

9

Air treatment and condensation

10

Air outlet

11

casing

100

System for cleaning room or city air

101

Air inlet

102

Suction pipe with coarse filter

103

Machine components and machine control

104

Devices for cleaning room or city air

105

Devices for cleaning room or city air

106

Devices for cleaning room or city air

107

Air recirculation

108

Air outlet

Example:

Assimilation of CO ₂ from supply air by means of a photobioreactor

To determine the cleaning performance of a photobioreactor containing microalgae, the decrease in the CO ₂ concentration at two different inlet concentrations of CO ₂ in the supply air was determined.

A photobioreactor with a working volume of 24.5 L was used for this purpose. An axenic culture of the green alga Chlorella vulgaris was used as the photoautotrophic microorganism. The gas volume flow introduced into the microalgae culture was 550 l / h, which corresponds to a gas throughput of 0.37 vvm (vol. Air / vol. Culture medium / min). The microalgae were cultivated at a temperature of 24.2 ± 0.7 ° C. The photon flux density (light intensity) used was 380 μmol m ^-2 s ^-1 and was provided continuously by means of a high-pressure sodium vapor lamp. The culture medium was composed as follows: 0.56 g / L CaCl ₂ , 3.5 g / L Ocean Instant, 2.46 g / L MgSO ₄ × 7 H ₂ O, 5 mg / L CoSO ₄ × 7 H ₂ O, 0.5 mg / L CuSO ₄ × 5 H ₂ O, 20 mg / L MnCl ₂ × 4 H ₂ O, 5 mg / L Na ₂ MoO ₄ × 2 H ₂ O, 5 mg / L ZnSO ₄ × 7 H ₂ O, 11.75 mg / LC ₆ H ₅ FeO ₇ × H ₂ O. The pH fluctuated in a range from 7.4 to 8.5 during the cultivation. The nitrogen required for the growth of the microalgae was provided in the present example in the form of NH ₄ HCO ₃ , the target concentration of ammonium in the medium being 300 mg / L. _{A buffer composed of KH 2} PO ₄ and K ₂ HPO ₄ with a target phosphate concentration in the medium of 200 mg / L served as the source of phosphorus. The initial biomass concentration was adjusted to 2 g / L. The microalgae were cultivated in the photobioreactor up to a biomass concentration of 4.6 g / L. The results of the experiment are shown in Table 1. Table 1: CO ₂ assimilation by microalgae Input concentration (CO ₂ ) Gas throughput Growth rate CO ₂ decrease [ppm] [vvm] [g / L / d] [ppm] 2500 0.37 0.21 about 500 1500 0.37 0.21 about 500

QUOTES INCLUDED IN THE DESCRIPTION

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Patent literature cited

• EP 1326959 B1 [0011]

Claims (20)

A method for purifying room or city air while providing at least one valuable fraction in a device for purifying room or city air containing at least one photobioreactor, comprising the steps: a) Pre-cleaning of room or city air by separating particles with a particle size of at least 10 µm to obtain pre-cleaned supply air, b) cultivation of at least one microalgae culture in the at least one photobioreactor in the presence of the pre-cleaned supply air and a phosphorus-containing component until a threshold biomass concentration of the microalgae culture of 6 to 10 g / L is reached, c) Cultivation of the at least one microalgae culture having a threshold biomass concentration of 6 to 10 g / L with phosphorus limitation and in the presence of the pre-cleaned supply air up to a final biomass concentration of 9 to 20 g / L and d) Preservation of purified room or city air and at least one fraction of recyclable materials. Procedure according to Claim 1 , wherein pre-cleaned air is continuously introduced into the at least one photobioreactor containing at least one microalgae culture. Procedure according to Claim 1 or 2 , wherein the cultivation in step c) takes place in the presence of a growth-inhibiting amount of a substance. Method according to one of the preceding claims, wherein the cultivation of the at least one microalgae culture in step b) and / or step c) takes place with switching on artificial light, in particular LED light. Method according to one of the preceding claims, wherein the room or city air purified in steps a) to d) is adjusted to a humidity of 40 to 60% before leaving the at least one photobioreactor and the separated water is returned to the at least one photobioreactor. Method according to one of the preceding claims, wherein the room or city air purified in steps a) to d) passes through at least one hygiene filter before leaving the at least one photobioreactor. Method according to one of the preceding claims, wherein the at least one microalgae culture to be cultivated in step b) in the at least one photobioreactor has an initial biomass concentration of at least 0.2 g / L, preferably at least 0.5 g / L, preferably at least 1.0 g / L, preferably at least 1.5 g / L. Method according to one of the preceding claims, wherein the at least one microalgae culture is a unialgal culture, preferably axenic culture. Procedure according to Claim 8 , the unialgal culture, preferably axenic culture, being selected from the group consisting of: Chlorella, Chlamydomonas, Phaeodactylum, Nannochloropsis, Haematococcus, Diacronema, Synechococcus, Thermosynechococcus, Synechocystis, Porphyridium, Microchloropsis, Scenedesmus and Dunaliella. Method according to one of the preceding claims, wherein the at least one microalgae culture is a mixed culture. Method according to one of the preceding claims, wherein the at least one photobioreactor is an airlift photobioreactor. Method according to one of the preceding claims, wherein at least one photobioreactor of the device is exchangeable. Procedure according to Claim 12 , wherein the at least one microalgae culture is harvested after step d) by exchanging at least one photobioreactor of the device. Procedure according to Claim 12 or 13th , at least one photobioreactor being able to be replaced while the device is in operation. Recyclable fraction obtainable from one of the processes of Claims 1 to 14th . Device for performing the method according to one of the Claims 1 to 14th , comprising i) at least one inlet for room or city air, ii) at least one device for separating particles with a particle size of at least 10 µm, iii) at least one photobioreactor and iv) at least one outlet for purified room or city air, wherein the at least one photobioreactor of the device is exchangeable. Device according to Claim 16 , wherein the device comprises at least two photobioreactors, of which at least one photobioreactor is exchangeable. Device according to Claim 16 or 17th wherein the device comprises at least one artificial light source. Plant for the purification of room or city air with the provision of at least one valuable material fraction, comprising at least two devices according to one of the Claims 16 to 18th , wherein the at least two devices in the system are arranged one above the other and each rotated relative to one another. Plant after Claim 19 , the at least two devices in the system being arranged one above the other and each rotated by at least 30 °, preferably at least 45 °, preferably at least 60 °, preferably by at least 75 °, preferably by at least 90 °.

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