A bioreactor and anaerobic reaction test device

Abstract

The application discloses a kind of bioreactor and anaerobic reaction test device, belong to kitchen waste processing equipment technical field, including anaerobic reactor, magnetite fixing device and reflux pipe, magnetite fixing device is placed in the middle region of anaerobic reactor to separate anaerobic reactor into upper cavity and lower cavity;Magnetite fixing device includes magnetite and fluid passage, magnetic field is formed between magnetite and magnetite;Fluid passage penetrates magnetite fixing device, and the through hole that magnetite is equipped with and fluid passage are communicated or magnetite is placed in the position of not blocking the fluid passage;Liquid pump is equipped on the one end of reflux pipe for communicating lower cavity and upper cavity;The generation amount and reaction efficiency of volatile fatty acid in the anaerobic hydrolysis acidification process of high load organic matter are improved by the above scheme.

Description

Technical Field

[0001] This invention relates to the field of equipment technology for food waste treatment, and in particular to a bioreactor and anaerobic reaction experimental device. Background Technology

[0002] Food waste contains high concentrations of organic matter (such as carbohydrates, proteins, lipids, etc.) and is a renewable resource with potential recycling value. Among the methods of treating food waste, anaerobic digestion has gradually become a popular research direction.

[0003] Compared to the value of biogas ($0.72 / cubic meter), volatile fatty acids have a higher commercial value ($50-130 / ton); and compared to biogas production, anaerobic hydrolysis and acidification of kitchen waste can generate more emission reductions; in addition, purified and separated volatile fatty acids can be used as substitutes for industrial raw materials such as petroleum, and have potential application value in the synthesis of plastics, cosmetics, pharmaceuticals and other industries. Therefore, the technology of producing volatile fatty acids through anaerobic hydrolysis and acidification is gradually gaining favor in countries around the world.

[0004] In the anaerobic digestion of food waste, high-molecular-weight substrates (such as polysaccharides, proteins, and lipids) are first hydrolyzed into low-molecular-weight substrates (such as monosaccharides, amino acids, and long-chain fatty acids) by hydrolytic bacteria. These low-molecular-weight organic compounds are then further degraded into volatile fatty acids and other substances by acid-producing bacteria. Subsequently, under suitable conditions, methanogens decompose the ethanol, organic acids, and H2 produced in the acidification stage into CH4 and CO2. Therefore, enhancing the metabolic efficiency of hydrolytic and acid-producing bacteria during the hydrolysis and acidification process, while simultaneously inhibiting the activity of methanogens, is crucial for achieving high yields of volatile fatty acids.

[0005] pH adjustment is commonly used to suppress methanogens. However, when the substrate-to-inoculum ratio increases to a high loading level, the formation of volatile fatty acids during anaerobic hydrolysis acidification is inhibited because the pH value falls below the dissociation constant of volatile fatty acids (pH < 4). This is because the high energy consumption required to maintain microbial cell reproduction means that undissociated acid hinders the productivity of hydrolytic and acid-producing bacteria, making the anaerobic hydrolysis acidification process take longer. Those skilled in the art have found that magnetite possesses certain reducing properties and strong magnetism, providing a suitable living environment for microorganisms, including reducing dissolved oxygen in water and providing a weak magnetic field, which is conducive to the growth and accumulation of anaerobic ammonia-oxidizing microorganisms, thereby increasing sludge activity and enhancing biological treatment effects. However, this approach does not play a sufficient role in the formation of volatile fatty acids during anaerobic hydrolysis acidification.

[0006] Therefore, how to provide a bioreactor to increase the generation of volatile fatty acids during the anaerobic hydrolysis and acidification process of magnetite is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to address the deficiencies and shortcomings of existing technologies by providing a bioreactor and anaerobic reaction experimental device to increase the generation of volatile fatty acids and reaction efficiency during anaerobic hydrolysis and acidification.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] This invention provides a bioreactor, including an anaerobic reactor, a magnetite fixing device, and a reflux pipe. The magnetite fixing device is installed inside the anaerobic reactor to separate the internal space of the anaerobic reactor into an upper cavity and a lower cavity. The upper cavity is used to hold a mixture of kitchen waste, inoculated sludge, and magnetite, and the lower cavity is used to hold the fermentation liquid generated by the reaction.

[0010] The magnetite fixing device includes a magnetite and a fluid channel. A magnetic field is formed between the magnetite and the magnetite placed on the magnetite fixing device. The fluid channel passes through the upper and lower surfaces of the magnetite fixing device, and the magnetite is provided with a through hole that communicates with the fluid channel or the magnetite is placed in a position that does not block the fluid channel.

[0011] A liquid pump is provided on the reflux pipe used to connect the lower cavity and the upper cavity.

[0012] In one embodiment, the magnetite fixing device further includes a housing for enclosing the magnetite, the magnetite being in contact with the magnetite through the housing, and the housing being made of a non-magnetic material at least on the side closest to the magnetite.

[0013] In one embodiment, the housing has a plurality of second cavities that can be sealed, and the magnet is placed in the second cavity.

[0014] In one embodiment, the housing includes a top cover, a base, and partitions. The top cover and the base are both sieve plates made of non-magnetic material. The edge of the top cover is detachably connected to the base through a sealing structure. A cavity is formed between the top cover and the base. A plurality of partitions arranged in a cross pattern are placed in the cavity. A second cavity is formed in the area of ​​the sieve plate where no sieve holes are provided.

[0015] In one embodiment, the sieve holes on the top cover and the corresponding sieve holes on the base are on the same vertical line.

[0016] In one embodiment, the inner wall of the anaerobic reactor is provided with at least two flanges located on the same radial cross-section, and the magnetite fixing device is placed on the upper surface of the flanges.

[0017] In one embodiment, the return pipe is further provided with a flow meter.

[0018] In one embodiment, the bioreactor further includes a collection pipe located on the side of the reflux pipe near the lower cavity and connected to the fermentation broth storage device, and the collection pipe is equipped with a switch valve.

[0019] In one embodiment, the cover of the anaerobic reactor is provided with at least two nozzles connected to the reflux pipe, and the nozzles are distributed at radial intervals along the cover.

[0020] The present invention also provides an anaerobic reaction test device, including the bioreactor and the incubator, wherein the bioreactor is placed inside the incubator, and the incubator is provided with a heating component and a temperature measuring component that are respectively connected to a control device.

[0021] The present invention achieves the following technical effects compared to the prior art:

[0022] This invention utilizes a magnetite fixing device inside an anaerobic reactor. This device contains magnetite stones, creating a stronger magnetic field between the magnetite and the magnetite compared to magnetite alone. This strong magnetic field promotes electron transfer during the anaerobic hydrolysis and acidification process, increasing the activity and number of bacteria in the inoculated sludge to form a dominant microbial community, thereby improving the yield of volatile fatty acids and reaction efficiency. Furthermore, the anaerobic reactor is divided into an upper and lower chamber, with a reflux pipe pumping the fermentation liquid that seeps into the lower chamber back to the upper chamber. This disperses the aggregated magnetite, increasing the dispersion of magnetite particles and ensuring sufficient contact between the food waste and the magnetite, thus improving reaction efficiency. Moreover, the continuous contact between the fermentation liquid and the strong magnetic field further enhances the generation of volatile fatty acids and the reaction efficiency during the anaerobic hydrolysis and acidification process. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of the bioreactor (R2) of this application;

[0025] Figure 2 For magnetite fixing devices without a sealing structure;

[0026] Figure 3 A partial cross-sectional structural diagram of a magnetite fixing device;

[0027] Figure 4 A magnetite fixing device with a sealed structure;

[0028] Figure 5 A schematic diagram of the structure of an anaerobic reaction experimental apparatus containing the bioreactor of this application;

[0029] Figure 6 This is a schematic diagram of the structure of the bioreactor R0;

[0030] Figure 7 This is a schematic diagram of the structure of bioreactor R1;

[0031] Figure 8 This is a graph showing the trend of VFA production throughout the entire reaction cycle.

[0032] Figure 9 This is a schematic diagram showing the changes in soluble protein concentration throughout the entire reaction cycle.

[0033] Figure 10 This is a schematic diagram showing the changes in soluble carbohydrate concentration throughout the entire reaction cycle.

[0034] The components include: 1. Anaerobic reactor; 2. Magnetite fixing device; 3. Return pipe; 4. Upper cavity; 5. Lower cavity; 6. Fluid channel; 7. Liquid pump; 8. Shell; 9. Second cavity; 10. Top cover; 11. Base; 12. Baffle; 13. Sealing structure; 14. Sieve hole; 15. Flow meter; 16. Collection pipe; 17. Switch valve; 18. Cover; 19. Nozzle; 20. Material inlet; 21. Biogas outlet; 22. Incubator; 23. Cabinet heater. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] like Figures 1 to 4As shown, the present invention provides a bioreactor, including an anaerobic reactor 1, a magnetite fixing device 2, and a reflux pipe 3. The magnetite fixing device 2 is installed in the middle region of the anaerobic reactor 1 to separate the internal space of the anaerobic reactor 1 into an upper cavity 4 and a lower cavity 5. The upper cavity 4 is used to place a mixture of kitchen waste, inoculated sludge, and magnetite, and the lower cavity 5 is used to hold the fermentation liquid generated after the reaction of the materials in the upper cavity 4.

[0038] The magnetite fixing device 2 includes a magnetite and a fluid channel 6. A magnetic field is formed between the magnetite and the magnetite placed on the upper part of the magnetite fixing device 2. The fluid channel 6 runs through the upper and lower surfaces of the magnetite fixing device 2. The magnetite is provided with a through hole communicating with the fluid channel 6, or the magnetite is placed in a position that does not block the fluid channel 6, so as to connect the upper cavity 4 and the lower cavity 5 through the fluid channel 6, allowing the fermentation broth to flow into the lower cavity 5. A liquid pump 7 is provided on the return pipe 3 used to connect the lower cavity 5 and the upper cavity 4, so as to pump the fermentation broth mixed with the dominant bacterial group in the lower cavity 5 back to the upper cavity 4.

[0039] The magnetite introduced into the upper chamber 4 can enrich the dominant microbial community (specifically, hydrolytic and acid-producing bacteria) that promotes hydrolysis and acid production, accelerating the degradation of organic matter and the production of volatile fatty acids and other substances. This dominant microbial community can also be called the dominant bacterial community. Because the dominant bacterial community is enriched on the surface of the magnetite, and under the influence of magnetic force, the magnetite is concentrated in the area near the upper surface of the magnetite fixing device 2, meaning the dominant bacterial community is concentrated in the area near the upper surface of the magnetite fixing device 2. This results in insufficient contact between the dominant bacterial community and the food waste in the anaerobic reactor 1 that is farther from the upper surface of the magnetite fixing device 2, reducing the efficiency of the reaction system. By pumping the fermentation liquid mixed with the dominant bacterial community in the lower chamber 5 back to the upper chamber 4, the food waste far from the magnetite fixing device 2 can fully contact the dominant bacterial community. The reflux liquid injected into the upper chamber 4 can also, to some extent, disperse the accumulated magnetite, ensuring sufficient contact between the food waste and the magnetite, thus improving the reaction efficiency. Figure 8 The comparison of VFAs (volatile fatty acids) production between R1, R2 and R0 also clearly shows that fermentation reflux can effectively promote substrate dissolution and hydrolysis, shorten the reaction lag period, improve reaction efficiency, and effectively increase VFA production.

[0040] Furthermore, because the magnetic field strength formed between magnetite and magnetite is higher than that formed between magnetite molecules, the magnetic field formed between the magnetite fixing device 2 and the magnetite further accelerates the electron transfer rate during anaerobic hydrolysis compared to the case of magnetite alone. The magnetic field also effectively prevents the loss of magnetite, promoting the decomposition of macromolecular substrates into smaller molecules and soluble substances. By refluxing the fermentation broth, the fermentation broth continuously contacts the magnetic field, thereby achieving a positive accumulation and improvement in volatile fatty acid yield and reaction efficiency. Figure 8 The comparison of VFAs production between R1 and R2 also shows that setting up magnetite fixing device 2 has a positive effect on increasing VFAs production.

[0041] Furthermore, the magnetite fixing device 2 makes it easy to recover and recycle magnetite in situ after the reaction, reducing the cost of using and recycling magnetite.

[0042] The theoretical basis for the application of magnetite in anaerobic fermentation technology: Methanogenesis only occurs after the dissimilatory iron reduction reaction in the anaerobic system is completed. Therefore, when the energy supply from electron donors is insufficient, the thermodynamically unfavorable methanogenesis process will be inhibited. Besides "stealing" some electrons used for methanogenesis, dissimilatory iron-reducing bacteria also reduce solid Fe(III) to soluble Fe. 2+ Furthermore, the role of iron oxides as electronic conductors in promoting anaerobic digestion and methanogenesis will be further weakened, and the released Fe... 2+ Ions further provide the necessary nutrients for the cell proliferation and enrichment process of dissimilatory iron-reducing bacteria. In addition, magnetite itself, as an electron acceptor, competes with methanogens for electrons, thus inhibiting methanogenesis. Therefore, a higher magnetite content is more conducive to the dissimilatory iron reduction reaction and inhibits methanogenesis.

[0043] Magnetite can simultaneously increase the total yield of short- and medium-chain fatty acids and the formation rate of long-chain fatty acids. Magnetite can increase the abundance of key microorganisms involved in the aforementioned biological processes and, through the dissimilar iron reduction process, provide a better conductive environment for anaerobic microorganisms: Fe 2+ and Fe 3+ In the fermentation system, it exists in a redox cycle with magnetite and may act as an electron shuttle to transfer electrons from electron donors to acceptors, thereby improving electron transfer efficiency.

[0044] If the attraction of magnetite to magnetite is too strong, it will increase the aggregation of magnetite, reduce the gaps between magnetite particles, reduce the contact area between magnetite and kitchen waste, dominant bacteria and inoculated sludge, and weaken the reaction efficiency. Therefore, the magnetite fixing device 2 in this application also includes a magnetically conductive isolation shell 8 for covering magnetite. Magnetite contacts magnetite through the magnetically conductive isolation shell 8. The magnetically conductive isolation shell 8 is made of non-magnetic material at least on the side closest to magnetite to reduce the attraction of magnetite to magnetite, so that magnetite will not aggregate too densely.

[0045] In one embodiment, the magnetically conductive isolation housing 8 has several second cavities 9 that can be sealed. The magnet is placed in the second cavity 9 to avoid contact with the fermentation liquid, so as not to weaken the magnetism of the magnet and improve the service life of the magnet.

[0046] The magnetically conductive isolation housing 8 includes an upper cover 10, a base 11, and partitions 12. Both the upper cover 10 and the base 11 are sieve plates made of non-magnetic material. The edge of the upper cover 10 is detachably connected to the base 11 via a sealing structure 13. Several cross-arranged partitions 12 are placed between the upper cover 10 and the base 11, forming a second cavity 9 in the area of ​​the sieve plate where no sieve holes are provided. In use, the cross-arranged partitions 12 are first placed on the base 11, then the upper cover 10 is placed on top of the partitions 12. After aligning the edges of the upper cover 10 and the base 11, the upper cover 10 and the base 11 are connected together using the sealing structure 13. The sealing structure 13 can be a U-shaped sealing strip covering one side of the upper cover 10 and the other side of the base 11; or it can be a strip-shaped sealing block adhered between the upper cover 10 and the base 11.

[0047] In one embodiment, the sieve holes 14 on the top cover 10 and the corresponding sieve holes 14 on the base 11 are on the same vertical line to accelerate the penetration of the fermentation broth.

[0048] The anaerobic reactor 1 has multiple flanges located on the same radial cross-section on its inner wall, and the magnetite fixing device 2 is placed on the upper surface of the flanges. The flanges are arranged in a ring at intervals along the inner wall of the anaerobic reactor 1 to improve the placement stability of the magnetite fixing device 2. The connection between the magnetite fixing device 2 and the anaerobic reactor 1 can also be by bonding, screwing, snap-fitting, etc. The anaerobic reactor 1 is a cylindrical structure made of plexiglass with a diameter of 16cm and a height of 48cm. The material and shape of the anaerobic reactor 1 can also be other forms.

[0049] A flow meter 15 is also installed on the return pipe 3. The bioreactor also includes a collection pipe 16, which is located on the side of the return pipe 3 near the lower cavity 5 to connect the fermentation broth storage device and the lower cavity 5. A switch valve 17 is installed on the collection pipe 16. The cover 18 of the anaerobic reactor 1 is provided with at least two nozzles 19 connected to the return pipe 3. The nozzles 19 are radially spaced along the cover 18 so that the pumped-back fermentation broth impacts the magnetite at different locations, improving the dispersion of the magnetite. The cover 18 is also provided with a material inlet 20 and a biogas outlet 21, which is connected to a biogas collection device via a pipe.

[0050] like Figure 5 As shown, the present invention also provides an anaerobic reaction experimental device, including a bioreactor and an incubator 22. The bioreactor is placed inside the incubator 22. The incubator 22 is equipped with a heating element and a temperature measuring element that are respectively connected to a control device to maintain a constant temperature inside the incubator 22. The inner wall of the incubator 22 is covered with insulation material. The heating element is a sleeve-type heater 23, and other heating elements that can be used in the incubator 22 are also applicable to this application. The temperature measuring element is a temperature sensor.

[0051] Test instructions

[0052] The initial Fe3O4 addition was 10 g / L, as determined by previous research. The temperature in incubator 22 was maintained at 35 ± 1℃. Throughout the operation, the initial reaction conditions were set based on parameters yielding the maximum volatile fatty acid yield from previous batch experiments: the organic loading rate (OLR) was fixed at approximately 20 gVS / L / d, and the C / N ratio of the digested sludge and food waste was determined using an elemental analyzer. Initially, a mixture of inoculum and substrate (1:3, based on the VS ratio, i.e., the ratio of VS in the inoculum to the VS in the substrate, where VS is the volatile solids content) was injected into the digested sludge and food waste, totaling 3 kg. The hydraulic loading time (HRT) was 10 days, and the reactor was purged with nitrogen for 5 minutes. During the semi-continuous acid-producing fermentation process, to maintain a constant working volume in the bioreactor, 600 g of fermentation broth containing volatile fatty acids was discharged every two days, followed by the addition of 600 g of food waste fluid to the upper chamber 4. The flow rate controlled by flow meter 15 is determined by the seepage rate of the fermentation broth. It is generally believed that if the seepage exceeds 20% of the working volume, it may significantly affect the working efficiency of the original reaction system. At this time, it is necessary to start the liquid pump 7 to replenish the fermentation broth into the upper chamber 4. Fermentation broth samples are taken from the discharged broth every two days, and the system is run continuously for 16 days to measure various indicators.

[0053] The experimental results of this application are illustrated using a comparative experiment as an example. R0 is a single-phase reactor without fermentation broth circulation or a magnetic field (R1), serving as the control group. R1 and R2 are two-phase reactors separated by a filter screen. The reaction takes place in the upper chamber 4, and the fermentation broth in the lower chamber 5 is returned to the upper chamber 4 via a liquid pump 7, forming a circulation between the two phases. The circulation time is 12 hours per day. In R1, no magnetic field is placed in the filter screen, while in R2, 20 neodymium iron boron magnets (20*10*1mm in size) are fixed in the filter screen as a magnet interlayer. By comparing the total yield of volatile fatty acids in the three reactors during the reaction cycle, the performance of the reactor combining a magnetic field and fermentation broth circulation is determined. To ensure the accuracy of the experimental results, except for the differences mentioned above, the materials of the experimental apparatus, the single-phase volume, and the operating conditions of the semi-continuous experiment are all the same for R0, R1, and R2.

[0054] Total solids (TS) and volatile solids (VS) of food waste and inoculum were determined using international standard methods. Fermentation broth samples were centrifuged at 8000 rpm and 4°C for 10 min, then filtered through a 0.45 μm filter membrane, and the ammonia nitrogen, protein, soluble carbohydrates, and TOC were determined.

[0055] For the determination of VFAs, 3% phosphoric acid was added to the fermentation broth at a ratio of 9:1, followed by centrifugation at 10,000 rpm for 10 min, and then filtration through a 0.22 μm filter membrane. The concentration and composition of volatile fatty acids were then measured using a gas chromatograph equipped with an analytical column. Nitrogen was used as the carrier gas at a flow rate of 21.2 mL / min, and the injector and detector temperatures were 190 °C and 210 °C, respectively. The gas chromatograph column temperature was set to 100 °C for 2 min, then increased to 180 °C at a rate of 10 °C / min and held at 180 °C for 2 min. Triple parallel assays were designed for each sample.

[0056] from Figure 8 The results show that the acid production of R1 and R2 increased rapidly in the first four days, and then stabilized and slowly increased around days 6-8. In contrast, R0 increased slowly, and its VFAs only reached their peak and stabilized around day 12, resulting in the lowest total VFAs production of R0 throughout the entire reaction cycle. This indicates that fermentation broth circulation can effectively promote substrate dissolution and hydrolysis, shorten the reaction lag period, improve reaction efficiency, and effectively increase VFAs production. Furthermore, after day 6, the VFAs production of R2 was significantly higher than that of R1, with the largest increase of 17.8%. This is because after the anaerobic reaction stabilizes, hydrolysis and solubilization no longer play a major role, and the Fe3O4 content in the upper chamber 4 of R1 decreases, causing a decline in the production efficiency of the target product. This indirectly reflects the positive significance of setting up the magnetite fixing device 2 in R2 to retain Fe3O4.

[0057] Since the experiment was a semi-continuous reaction, the total VFAs yield during the reaction cycle should be calculated by adding the samples taken from the fermentation broth each time, in order to effectively reflect the working efficiency of each experimental group's reactor. The VFAs yields during the reaction phase are shown in Table 1. During the entire experimental cycle, the total acid production of R1 and R2 increased by 8.5% and 17.7% respectively compared to the control group R0. In summary, the fermentation broth circulation design can effectively promote the hydrolysis efficiency of the substrate, thereby increasing the anaerobic acid production of high-load kitchen waste. Furthermore, the comparison of R2 and R1 yields also shows that setting up the magnetite fixing device 2 can effectively prevent the loss of Fe3O4, avoid a decrease in reaction efficiency, and increase the yield of the target product.

[0058] Table 1 Total VFAs Production (mg C)

[0059] R0 124.76 508.41 747.67 934.95 1030.66 1181.20 1176.28 5818.41 11522.34 R1 230.67 874.61 1003.66 1014.59 994.50 1077.81 1108.97 5738.1 12042.91 R2 222.76 931.90 1092.99 1128.90 1171.93 1183.69 1168.16 5904.04 12804.37

[0060] The changing trends of soluble proteins and polysaccharides can reflect the solubility and hydrolysis efficiency of the substrate. For example... Figure 9 Throughout the entire experimental period, the protein concentrations in R1 and R2 were generally higher than those in R0, indicating that fermentation broth circulation can promote the hydrolysis of macromolecules in the substrate and improve reaction efficiency. The horizontal axis represents reaction time. However, both the increase rate of soluble protein on day 2 and the soluble protein concentration at the same time after day 4 were lower in R2 than in R1. This may be because the magnetic field in R2 promoted electron transfer between microorganisms, increasing the degradation rate of soluble proteins in the reactor. This caused the soluble proteins produced during hydrolysis to be further decomposed into smaller molecules, resulting in a lower concentration of soluble proteins in R2 compared to R1.

[0061] The changes in the concentration of soluble polysaccharides in each reactor are as follows: Figure 10 As shown, throughout the entire reaction phase, except for day 0, the carbohydrate concentrations in R1 and R2 were generally higher than those in R0. This is because as the semi-continuous experiment progresses, the organic load in the reactor continuously accumulates. The circulation of the fermentation broth can promote the increase in the solubility of soluble polysaccharides, achieving rapid degradation within the first two days. This demonstrates that the design of the fermentation broth circulation can still improve the hydrolysis efficiency of the substrate under high organic load conditions. Similarly, during the 6–16 days when the reaction output tends to stabilize, the concentration of soluble polysaccharides in R2 is generally slightly higher than that in R1. This indicates that under high load conditions, the magnetic field also helps to promote the decomposition of macromolecular substrates into soluble substances to some extent.

[0062] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A bioreactor, characterized in that: The device includes an anaerobic reactor, a magnetite fixing device, and a reflux pipe. The magnetite fixing device is installed inside the anaerobic reactor to separate the internal space of the anaerobic reactor into an upper cavity and a lower cavity. The upper cavity is used to hold a mixture of kitchen waste, inoculated sludge, and magnetite, and the lower cavity is used to hold the fermentation liquid generated by the reaction. The magnetite fixing device includes a magnetite and a fluid channel, wherein a magnetic field is formed between the magnetite and the magnetite placed on the magnetite fixing device; the fluid channel extends through the upper and lower surfaces of the magnetite fixing device, and the magnetite is positioned in a position that does not block the fluid channel; A liquid pump is provided on the reflux pipe used to connect the lower cavity and the upper cavity; The magnetite fixing device further includes a shell for covering the magnetite, the magnetite being in contact with the magnetite through the shell, and the shell being made of a non-magnetic material at least on the side closest to the magnetite; The shell has several second cavities that can be sealed, and the magnet is placed in the second cavity; The housing includes a top cover, a base, and partitions. The top cover and the base are both sieve plates made of non-magnetic materials. The edge of the top cover is detachably connected to the base through a sealing structure. A cavity is formed between the top cover and the base. Several partitions arranged in a cross pattern are placed in the cavity. A second cavity is formed in the area of ​​the sieve plate where no sieve holes are provided. The sieve holes on the top cover and the corresponding sieve holes on the base are on the same vertical line.

2. The bioreactor according to claim 1, characterized in that: The inner wall of the anaerobic reactor is provided with at least two flanges located on the same radial cross-section, and the magnetite fixing device is placed on the upper surface of the flanges.

3. The bioreactor according to claim 2, characterized in that: The return pipe is also equipped with a flow meter.

4. The bioreactor according to claim 3, characterized in that: The bioreactor also includes a collection pipe, which is located on the side of the reflux pipe near the lower cavity and connected to the fermentation broth storage device. The collection pipe is equipped with a switch valve.

5. The bioreactor according to claim 4, characterized in that: The anaerobic reactor has at least two nozzles on its cover that are connected to the reflux pipe, and the nozzles are distributed at radial intervals along the cover.

6. An anaerobic reaction experimental apparatus, characterized in that: The invention includes a bioreactor and an incubator as described in any one of claims 1 to 5, wherein the bioreactor is placed inside the incubator, and the incubator is provided with a heating element and a temperature measuring element that are respectively signal-connected to a control device.

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