Bioreactor and use thereof, method for producing an organic nutrient solution and for carbon dioxide storage

Abstract

A bioreactor (1, 2, 3) and use thereof for converting organic residual and/or waste materials into an organic nutrient solution with a proportion of at least 10% plant-available mineralized nitrogen relative to the total nitrogen content of the nutrient solution. A process for preparing an organic nutrient solution is also provided, as well as an organic nutrient solution, use of an organic nutrient solution as an absorbent for carbon dioxide storage, use of an organic nutrient solution as an agent for binding carbon in plants and soils and to a nutrient production and carbon dioxide storage system.

Claims

1. A process for producing an organic nutrient solution with a fraction of at least 10% of plant-available, mineralized nitrogen, based on a total nitrogen content of the organic nutrient solution, the process comprising the steps of: in a seeding step, seeding a carrier element (10) with a seed material which comprises ammonifying and/or nitrifying bacteria, forming a biofilm (12) with at least one of ammonifying or nitrifying bacteria on the carrier element (10), in an incubating step, incubating at least one of an organic residual or an organic waste material with the biofilm (12), where the at least one of the ammonifying or the nitrifying bacteria convert organically bonded nitrogen in the at least one of the residual or waste material into mineralized nitrogen, where during implementation of at least one of the seeding of the carrier element (10), the forming of the biofilm (12), or the incubating of the at least one of the organic residual or the organic waste material with the biofilm (12), oxygen is introduced into at least one of a reaction vessel (5) or the carrier element (10) by an aerating device (8), producing an organic nutrient solution by the preceding steps, and subsequently, in a carbon dioxide storage step, treating the organic nutrient solution with a carbon dioxide-containing gas, such that gaseous carbon dioxide is bound by the organic nutrient solution.

2. The process as claimed in claim 1, further comprising performing a surface enlargement of the organic nutrient solution in the carbon dioxide storage step.

3. The process as claimed in claim 2, wherein the surface enlargement is performed by passing the organic nutrient solution over a scrubber device.

4. The process as claimed in claim 1, wherein a nitrate fraction of the plant-available, mineralized nitrogen is higher than an ammonium fraction.

5. The process as claimed in claim 1, wherein carrier element (10) includes a colonization surface (11) for formation of the biofilm (12).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described more exactly below with reference to the figures, where

(2) FIG. 1 shows a first variant embodiment of a bioreactor with a plurality of plastic chips as carrier elements, joined together to form a tangle,

(3) FIG. 2 shows a second variant embodiment of a bioreactor with a plurality of carrier elements in the form of zeolite granules, disposed in a fabric pouch within the receiving space of the bioreactor,

(4) FIG. 3 shows a third variant embodiment of a bioreactor with three carrier elements each in the form of porous tubes, which are connected parallel to one another in a line within the receiving space,

(5) FIG. 4 shows a simplified representation of an overall-system overview of a variant embodiment of a nutrient generation and carbon dioxide storage system,

(6) FIG. 5 shows a simplified representation of one possible variant embodiment of a carbon dioxide storage apparatus with two chambers,

(7) FIG. 6 shows an experimental construction of a plurality of carbon dioxide storage apparatuses which are connected in parallel and which contain A) concentrated nutrient solution, B) nutrient solution or C) water as reference, as absorbents for CO.sub.2 storage,

(8) FIG. 7 shows the result of the experiment shown in FIG. 6, with A) concentrated nutrient solution shown with the narrow-dashed graph, B) nutrient solution shown with the wide-dashed graph, and C) water shown as a solid line.

DETAILED DESCRIPTION

(9) FIGS. 1 to 3 show three different exemplary embodiments of a bioreactor, each identified as a whole by 1, 2 or 3. The bioreactors 1, 2 and 3 are configured for the conversion of organic residual and/or waste materials into an organic nutrient solution with a relatively high fraction of plant-available mineralized nitrogen.

(10) By means of the bioreactor 1, 2, 3, therefore, a process for producing the organic nutrient solution can be carried out, where a fraction of at least 10% of plant-available nitrogen is envisaged, based on the total nitrogen content of the nutrient solution. Moreover, for the plant-available mineralized nitrogen, the nitrate fraction is to be higher than the ammonium fraction.

(11) The bioreactor 1, 2, 3 comprises a reaction vessel 5 into which a feed line 6 opens and from which a drain line 7 exits. Via the feed line 6 a suspension 4 can be introduced into the reaction vessel, and via the drain line 7 the suspension can be discharged again after passage through the reaction vessel 5.

(12) The bioreactor 1, 2, 3 comprises an aeration device 8 via which oxygen, preferably in the form of air, can be introduced into the reaction vessel 5. In the exemplary embodiments shown in FIGS. 1 to 3, the aeration device 8 has a compressor 17. Using the compressor 17, oxygen in the form of air can be introduced into the reaction vessel 5 by way of a gas supply line 16.

(13) The three bioreactors 1, 2 and 3 differ essentially in having different carrier elements 10, each disposed within a receiving space 9 of the reaction vessel 5. The carrier elements 10 are disposed within the receiving space 9 in such a way that the suspension 4 introduced via the feed line 6 is able to flow around the carrier elements 10. The suspension 4 may be, for example, an organic residual and/or waste material, as described above, and/or an organic seeding material, as described above. Additionally, the carrier elements 10 are also arranged in such a way that the oxygen introduced by means of the aeration device 8 flows around the carrier element 10, preferably substantially on all sides.

(14) The carrier elements 10 have a particularly large surface in relation to their volume. The surfaces of the carrier elements 10 here are designed as colonization surfaces 11 for the development of a biofilm 12, which consists at least partially of ammonifying and/or nitrifying bacteria. The colonization surfaces 11 are therefore designed, for example, to be rougher than an inner side of a reaction vessel wall. This allows the microorganisms in the biofilm 12 to adhere particularly well to the colonization surfaces 11 and to grow on them. This makes it possible for the ammonifying and/or nitrifying bacteria to form a biofilm 12 substantially on the colonization surfaces 11, since here ideal growth conditions can be generated.

(15) The carrier elements 10 of the various exemplary embodiments in FIGS. 1 to 3 are produced in part of different materials or combinations of multiple materials.

(16) The carrier elements 10 of the bioreactor 1 from FIG. 1 are produced as chips 13 made of plastic. For example, these chips 13 may arise as waste products when machining a plastic blank. It may be particularly advantageous here for the chips to consist of a thermoplastic, such as a polypropylene and/or polyethylene, for example. The multiplicity of chips 13 are disposed in an unordered way within the receiving space 9 of the reaction vessel 5. The result is a real entanglement of the chips 13. Because the chips 13 have a curved colonization surface 11, which may form, for example, because of a serpentine and/or spiral and/or wavy form of the chips 13, it is easily possible to prevent the colonization surfaces 11 of individual chips 13 from sticking to or lying on one another. Sticking or lying is disadvantageous since gas exchange and/or surrounding flow would no longer be able to be guaranteed and consequently a biofilm of anaerobic bacteria might be formed. This could result exactly in the unwanted effect of denitrification processes occurring in particular.

(17) In the case of the bioreactor 2 from FIG. 2, the carrier elements 10 take the form of zeolite granules 14. In order to be able to prevent the granules 14 depositing in regions of the receiving space 9 where there is poor transit flow or poor aeration, the carrier elements 10 in the form of granules 14 are disposed in a collecting unit 27, designed as a fabric pouch. The collecting unit 27 may be securable within the receiving space by means of a hanger. Within the collecting unit 27 there is a further aeration device 28, which can be supplied with oxygen via a bypass gas line 25. Furthermore, a supply line 6 extending within the reaction vessel 5 leads into the collecting unit 27 and ends there, so allowing the suspension 4 to be introduced directly into the collecting unit 27. The collecting unit 27 has an open porosity, allowing the suspension to emerge from the collecting unit 27 into the receiving space 9. The bypass gas line 25 branches off from a main gas line 26, which is connected to the aeration device 8. Accordingly it is possible to introduce oxygen into the receiving space 9 at two different locations, without the need for a second compressor 17.

(18) The bioreactor 3 from FIG. 3 comprises three carrier elements 10, which are each designed as porous tubes 15 and which are integrated parallel to one another into a line system within the receiving space 9. The tubes 15 are each connected to the feed line 6 and to a gas supply line 16, which takes the form of a bypass gas line 25. In this way, suspension 4 and oxygen can be introduced into the tubes 15, in particular at separate times. In order to stop the introduction of oxygen or suspension 4 into a tube 15 or two or more of the tubes 15, a shut-off valve 34 is arranged upstream of each tube 15 in the flow direction, in the feed line 6.

(19) In order to be able to increase a tube internal pressure in a tube 15 or in two or more tubes 15, independently in particular of the other tubes 15, a further shut-off valve 35 is disposed downstream of each tube 15 in each case, in the flow direction of the suspension 4. By shutting off a valve 35, it is possible to prevent the suspension exiting from the tube 15 via the drain line 7 extending within the receiving space 9. The suspension 4 is therefore able to emerge via the pores in a tube wall into the receiving space 9. Because the tube 15 is preferably of stretchable design, an enlargement of the pores in the tube wall can be achieved by raising the pressure within the tube 15. The bioreactor 3 comprises a further drain line 7, via which suspension 4 can be discharged from the receiving space 9 in the event of the first drain line 7 being shut off.

(20) The aeration device 8 comprises an aeration plate 19 disposed on a base 18 of the reaction vessel 5 of the bioreactor 1, 2, 3. The aeration plate 19 is connected to the compressor 17 via a gas supply line 16, more particularly the main gas line 26. The aeration plate 19 has a plurality of uniformly distributed aeration openings 20, via which oxygen can flow into the suspension 4.

(21) The bioreactor 1, 2, 3 comprises in each case a pumping apparatus 21, which may be designed in particular as a centrifugal pump or circulating pump. By means of the pumping apparatus 21 it is possible to pump the suspension 4 through the feed line 6 into the reaction vessel 5 and to draw it off from the reaction vessel 5 via the drain line 7.

(22) The bioreactor 1, 2, 3 therefore comprises a suspension circuit 29, which consists of the feed lines 6, the drain lines 7 and the reaction vessel 5, and in which the suspension 4 can be circulated by means of the pumping apparatus 21. The pumping apparatus 21 is configured such that it is possible to reverse a suspension flow direction within the reaction vessel 5 and/or within the lines of the bioreactor 1, 2, 3. In combination with a plurality of shut-off valves 30, 31, 34, 35, it is possible to adjust and vary the flow direction within the reaction vessel 5.

(23) Branching off from the feed line 6, as shown in FIGS. 1 to 3, there may be, for example, a bypass feed line 32, which opens into the receiving space 9 of the reaction vessel 5. If the suspension flow direction is reversed, a feed line 6 of the plurality of feed lines 6 may change function to become a drain line 7, and/or the bypass feed line 32 may change function to become a drain line 7. The function of the respective line is therefore dependent on the flow direction of the suspension 4, which is dictated by the pumping apparatus 21. Generally, however, it may be stated that feed lines 6 open into the receiving space 9 of the reaction vessel 5 above or at least at the same height as the drain lines 7. In this way it is possible to achieve better circulation of the suspension within the reaction vessel 5.

(24) In order to be able to take the carrier element 10 out of the receiving space 9 easily, the bioreactor 1, 2, 3 comprises an opening 23 on a top side of the reaction vessel 5. By means of a closure unit 24 in the form of a lid, this opening 23 can be closed in a manner impervious to fluid and/or resistant to pressure, while the bioreactor 1, 2, 3 is in use.

(25) In the upper third of the receiving space 9, the bioreactor 1 has a divider unit 36, via which the suspension 4 can be divided into a plurality of individual jets. This makes it possible on the one hand to divide up solids that are adhering to one another, and on the other hand to achieve additional aeration of the suspension. The divider unit 36 may be designed, for example, as a divider plate. Furthermore, this divider unit 36 may also be combined in the case of the other variant embodiments of FIGS. 2 and 3, or with the features from the claims.

(26) The bioreactor 1, 2, 3 additionally comprises a heating apparatus 22, which allows the receiving space 9 and/or the suspension 4 contained therein to be heated to a desired temperature.

(27) As can be seen in FIG. 3, it is possible for a shut-off valve 33 to be disposed in the bypass gas line 25. In this way the introduction of oxygen into the receiving space 9 of the reaction vessel 5 can be prevented, while at the same time, however, aeration via the aeration plate 19 can take place.

(28) In order to generate a biofilm 12 of at least partly ammonifying and/or nitrifying bacteria, a suspension with water is produced from a particulate organic seeding material. Serving as the seeding material here may be a worm excrement or worm earth, for example. Other possible seeding materials have already been described comprehensively above. Fundamentally it may be stated that the seed material suitably comprises, in principle, all organic substances which contain proteolytic soil bacteria.

(29) For optimal biofilm formation, the seed material is contacted with the carrier material 10 by circulation and fluidization by means of blown-in air. The organic seed material has a heightened concentration of soil bacteria, mucilage and other proteins, and also of inorganic minerals, which carry dead bacterial material. These ingredients firstly support the adhesion of the bacteria that are present on the carrier element 10, and hence support biofilm formation. Furthermore, they also serve as nutrients for the bacteria. The result is a carrier element 10 having a diverse bacterial culture, which can be modified and altered in terms of quality and quantity and which consists of a multiplicity of soil bacteria including ammonifying and nitrifying bacteria.

(30) After formation of the biofilm 12 on the carrier element 10, the carrier material 10 may be taken from a first reaction vessel 5 and transferred to a further reaction vessel 5. Conversion of an organic residual and/or waste material into an organic nutrient solution can then be performed using the biofilm. It is also conceivable, however, for the seeding step and the incubating step to be carried out in the same reaction vessel 5. In that case it is advisable to remove the seed material from the reaction vessel 5 before adding the organic residual and/or waste material.

(31) The invention thus relates in particular to a bioreactor 1, 2, 3 and the use thereof for converting organic residual and/or waste materials into an organic nutrient solution with a fraction of at least 10% of plant-available mineralized nitrogen, based on the total nitrogen content of the nutrient solution, having a reaction vessel 5, where the reaction vessel 5 comprises a feed line 6 via which a suspension 4 can be introduced into the reaction vessel 5, and where the reaction vessel 5 comprises a drain line 7 via which the suspension 4 can be discharged from the reaction vessel 5, and having an aeration device 8 for aerating the suspension 4 and/or a carrier element 10 disposed within the reaction vessel 5, where the carrier element 10 has at least one inner and one outer colonization surface 11, on each of which ammonifying and/or nitrifying bacteria can colonize in a biofilm 12.

(32) FIG. 4 shows a nutrient generation and carbon dioxide storage system 37, which comprises a fermentation apparatus 38 for generating biogas and an organic residual and/or waste material, a combined heat and power plant 39 for burning a biogas, generated by the fermentation apparatus 38, to obtain electrical energy and/or heat, a bioreactor 1, 2, 3 for converting organic residual and/or waste materials into an organic nutrient solution, and a carbon dioxide storage apparatus 40 having a carbon dioxide storage space 41, preferably an externally sealable carbon dioxide storage space 41, in which at least one scrubber device 42 is disposed, which is configured to implement a liquid-gas reaction between a carbon dioxide-containing gas, more particularly a biogas and/or a flue gas from a combined heat and power plant 39, and the organic nutrient solution produced by the bioreactor 1, 2, 3.

(33) Carbon dioxide formed by the fermentation process in the fermentation apparatus 38 can be passed into the carbon dioxide storage apparatus 40 via a line 43 in the form of a gas line. The organic residual and waste material (fermentation residue) is passed into the bioreactor 1, 2, 3 from the fermentation apparatus 38 as a starting material for the production of the organic nutrient solution. Biogas produced in the fermentation apparatus 38 can be burned by means of the combined heat and power plant 39. Carbon dioxide formed in that process is likewise passed into the carbon dioxide storage apparatus 40.

(34) The organic nutrient solution produced in the bioreactor 1, 2, 3 from the residual and waste material (fermentation residue) is subsequently conveyed from the bioreactor 1, 2, 3 via a line 43 into the carbon dioxide storage space 41. There it is mixed with the carbon dioxide-containing gas from the fermentation apparatus 38 and the combined heat and power plant 39.

(35) FIG. 5 shows the process of CO.sub.2 storage by the organic nutrient solution in the carbon dioxide storage apparatus 40.

(36) The carbon dioxide storage space 41 of the carbon dioxide storage apparatus 40 is subdivided into two chambers 44, 45. By means of the pumping apparatus 46, the organic nutrient solution can be pumped back and forth between the chambers 44, 45. In the first chamber 44 there is a scrubber device 42. This may take the form, for example, of a bubble column reactor, tubular reactor, jet nozzle reactor, stirred tank, thin-film reactor and/or spraying tower. Critical to improved CO.sub.2 binding is the production of as large as possible an interface between the organic nutrient solution and the gas.

(37) The carbon dioxide storage apparatuses 40 in FIG. 6 are all designed the same, in order to create uniform experimental conditions. As can be seen from FIG. 7, given the same treatment time, the result with the concentrated nutrient solution is the best. This allows the most CO.sub.2/liquid volume to be bound.

(38) The composition of the samples A (concentrated nutrient solution), B (nutrient solution) and C (reference=water) is as follows:

(39) TABLE-US-00007 Scrubber A Absorbent: soilingNRF concentrated Gas volume in l: 82 Liquid quantity in circulation in l: 2.93 Gas/liquid volume coefficient: 28 Temperature of liquid 25 degrees C. pH NH4 mg/l * NO3 mg/l * Ca CO3 mg/l * K mg/l * 8.3 80 1750 70 3750 * Measured with test strips from MerckKGA, Darmstadt; MQuant. The concentration is determined by visual comparison of the reaction zone on the test strip with the fields of a color scale

(40) TABLE-US-00008 Scrubber B Absorbent: soilingNRF Gas volume in l: 56 Liquid quantity in circulation in l: 53 Gas/liquid volume coefficient: 1.05 Temperature of liquid: 25 degrees C. pH NH4 mg/l* NO3 mg/l* Ca CO3 mg/l* K mg/l* 5.7 8 450 90 375 *Measured with test strips from MerckKGA, Darmstadt; MQuant. The concentration is determined by visual comparison of the reaction zone on the test strip with the fields of a color scale

(41) TABLE-US-00009 Scrubber C Absorbent: water Gas volume in l: 56 Liquid quantity in circulation in l: 49 Gas/liquid volume coefficient: 1.14 Temperature of liquid 25 degrees C. pH NH4 mg/l* NO3 mg/l* Ca CO3 mg/l* K mg/l* 6.3 0 3 80 0 *Measured with test strips from MerckKGA, Darmstadt; MQuant. The concentration is determined by visual comparison of the reaction zone on the test strip with the fields of a color scale

(42) The gas mixture from the exhaust gases of a combustion engine is fed to the carbon dioxide storage apparatus A, B and C for around 10 minutes and then the access ports are provided with gas-tight sealing. The CO.sub.2 content is measured at the start of the scrubber function and then after hours 1, 2, 3 and 4. The measuring instrument (testo 330-2 LX; flue gas analyzer from Testo SE and Co KGaA, Lenzkirch) determines the fraction of CO.sub.2 in the gas mixture.

(43) The result of the experiment may be gathered from the table below and from the associated diagram from FIG. 7.

(44) Result of experiment:

(45) TABLE-US-00010 Start 1 h 2 h 3 h 4 h soiling CO2 in % 1.13 0.85 0.79 0.79 0.62 NRF Loading of the 0 0.28 0.34 0.34 0.51 concentrated liquid A Loading weighted 0 7.8 9.5 9.5 14.3 by gas/liquid coefficient soiling CO2 in % 1.19 1.02 0.91 0.91 0.74 NRF Loading of the 0 0.17 0.28 0.28 0.45 B liquid Loading weighted 0 0.2 0.3 0.3 0.5 by gas/liquid coefficient Water CO2 in % 1.08 1.02 0.79 0.79 0.76 C Loading of the 0 0.06 0.29 0.29 0.32 liquid Loading weighted 0 0.1 0.3 0.3 by gas/liquid coefficient

(46) The CO.sub.2 concentration at the start of the series of experiments was around 30 times higher than the CO.sub.2 concentration of 0.038% in air.

(47) After 4 hours of running, the absorbent liquids of scrubbers A, B and C are subjected to measurement, the resulting values being as follows:

(48) TABLE-US-00011 Scrubber A with soilingNRCO2capF concentrated pH NH4 mg/l * NO3 mg/1 * Ca CO3 mg/1 * K mg/1 * 6.4 20 1750 200 125 * Measured with test strips from MerckKGA, Darmstadt; MQuant. The concentration is determined by visual comparison of the reaction zone on the test strip with the fields of a color scale

(49) TABLE-US-00012 Scrubber B with soilingNRCO2capF pH NH4 mg/l * NO3 mg/l * Ca CO3 mg/l * K mg/l * 5.3 5 450 120 170 * Measured with test strips from MerckKGA, Darmstadt; MQuant. The concentration is determined by visual comparison of the reaction zone on the test strip with the fields of a color scale

(50) TABLE-US-00013 Scrubber C with water pH NH4 mg/l * NO3 mg/l * Ca CO3 mg/l * K mg/l * 6 0 3 130 0 * Measured with test strips from MerckKGA, Darmstadt; MQuant. The concentration is determined by visual comparison of the reaction zone on the test strip with the fields of a color scale

(51) Particularly effective CO.sub.2 storage was possible by means of the concentrated nutrient solution (A) and the nutrient solution (B).

(52) The invention is also suitable for the binding and/or as an absorbent of COx, NOx and SOx from fermentation gases and combustion gases formed in biogas recovery and biogas combustion and also in the combustion of fossil fuels.

(53) The system is therefore especially suitable for implementing the process, described and/or claimed herein, for the production of an organic nutrient solution and/or carbon dioxide storage.

LIST OF REFERENCE SYMBOLS

(54) 1, 2, 3 Bioreactor 4 Suspension 5 Reaction vessel 6 Feed line 7 Drain line 8 Aeration device 9 Receiving space 10 Carrier element 11 Colonization surface 12 Biofilm 13 Chips 14 Granules 15 Tube 16 Gas supply line 17 Compressor 18 Base of the reaction vessel 19 Aeration plate 20 Aeration openings 21 Pumping apparatus 22 Heating apparatus 23 Opening 24 Closure unit 25 Bypass gas line 26 Main gas line 27 Collecting unit 28 Further aeration device 29 Suspension circuit 30 Shut-off valve 31 Shut-off valve 32 Bypass feed line 33 Shut-off valve (air) 34 Shut-off valve in the reaction vessel 35 Shut-off valve in the reaction vessel 36 Divider unit 37 Nutrient generation and carbon dioxide storage system 38 Fermentation apparatus, more particularly a biogas plant 39 Combined heat and power plant 40 Carbon dioxide storage apparatus 41 Carbon dioxide storage space 42 Scrubber device 43 Line 44 Scrubber device chamber 45 Collecting chamber 46 Pumping apparatus 47 Carbon dioxide measuring device