Multi-element organic waste anaerobic fermentation system

Abstract

The invention discloses a multi-element organic waste anaerobic fermentation system which comprises a first pretreatment device, a second pretreatment device, a hydrogen-producing and acid-producing fermentation reactor, a nano bubble generator and a methane-producing fermentation reactor, the first pretreatment device and the second pretreatment device are respectively used for pretreating the easily degradable organic wastes and the difficultly degradable organic wastes; the hydrogen-producing and acid-producing fermentation reactor is used for performing hydrogen-producing and acid-producing fermentation on the pretreated easily-degradable wastes to produce hydrogen-containing tail gas and first fermentation feed liquid; the nano bubble generator is used for preparing nano bubble water from the hydrogen-containing tail gas; and the methanogenesis fermentation reactor is used for performing methanogenesis fermentation on the first fermentation material liquid, the nano bubble water and the pretreated refractory organic waste to generate methane and second fermentation material liquid. The method not only solves the problem of treatment of various organic wastes, but also realizes resource utilization of the wastes, and has remarkable environmental benefits and economic benefits.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of biological fermentation technology, and particularly relates to an anaerobic fermentation system for multiple organic wastes. BACKGROUND

[0002] In the field of organic waste treatment, according to the degradation characteristics of the materials, they can be divided into two categories: 1. easily degradable organic waste: the main components are simple organic matters (sugars, starches, proteins, fatty acids, etc.), such as kitchen waste, food processing waste, domestic sewage sludge, etc. This kind of material contains a high proportion of carbohydrates, proteins and fats, and has a fast hydrolysis rate, but often faces problems such as rapid acidification and ammonia inhibition; 2. difficult-to-degrade organic waste: such as crop straw, forestry waste and landscaping waste, etc. This kind of material is rich in cellulose, hemicellulose and lignin, etc. complex polysaccharides, and microorganisms are difficult to directly utilize, and hydrolysis is the rate-limiting step of anaerobic digestion.

[0003] The accumulation of these two types of organic waste with different characteristics not only causes serious damage to the atmosphere, water resources and the ecological system, but also threatens human health and quality of life. Using anaerobic fermentation technology to utilize these wastes for energy production not only can strengthen the supply chain of biofuels, but also can avoid the use of edible resources and the disadvantages of competing with people for food, in line with the scientific concept of development.

[0004] However, the anaerobic fermentation of single type of organic waste still faces many technical challenges. Easily degradable organic waste often faces problems such as nutrient imbalance, organic acid (volatile fatty acid and long-chain fatty acid) accumulation and ammonia inhibition; difficult-to-degrade organic waste has low hydrolysis efficiency, imbalance of carbon and nitrogen ratio, and long gas production period. Therefore, the development of low-cost, efficient and high-value co-fermentation process of different characteristics of organic waste has become an urgent need under the strategy of sustainable development in China.

[0005] In the traditional anaerobic fermentation process, the conversion of organic matter generally includes three stages: hydrolysis acidification, hydrogen and acetic acid production, and methanation: in the hydrolysis acidification stage, under anaerobic conditions, macromolecular organic matter is decomposed into small molecular organic matter such as amino acids, monosaccharides and fatty acids, etc. by the action of hydrolytic enzymes; in the hydrogen and acetic acid production stage, small molecular organic matter is converted into acetic acid and hydrogen under the action of hydrogen and acetic acid producing bacteria. At the same time, part of the acetic acid will be further converted into methane; in the methanation stage, acetic acid and hydrogen are converted into methane and carbon dioxide under the action of methanogens.

[0006] In traditional technologies, all three stages are completed in the same reactor (generally referred to as single-stage hydrogen production), which cannot differentiate the treatment of materials with different degradation characteristics, resulting in low raw material utilization, methane yield, and purity. In recent years, studies have separated the pre-methanation stages (hydrolysis acidification and hydrogen and acetic acid production stages) from the methanation stage into different reactors (generally referred to as two-stage fermentation hydrogen production). The methanation stage utilizes the hydrogen-producing fermentation tail liquid from the previous stage for methanogenesis, which not only shortens the fermentation cycle but also significantly improves the biomass conversion rate.

[0007] Based on the two-stage co-fermentation, the hydrogen-nutritive methane generation pathway is enhanced, and the acid-producing waste gas ( and ) transformed into (Hydrogen-alkane co-fermentation) is an effective means to increase the total energy yield in anaerobic fermentation. However, in actual production, the benefits of directly using hydrogen to increase methane production during fermentation are limited due to low hydrogen production rates and low heat and mass transfer efficiency. Therefore, finding economical and efficient fermentation hydrogen production enhancement processes, improving the heat and mass transfer efficiency in the hydrogen-nutritive methane generation pathway, and rationally matching them with two-stage co-fermentation processes to establish economical and efficient anaerobic fermentation systems suitable for organic wastes with different degradation characteristics are key to promoting the development of the biogas industry. Summary of the Invention

[0008] The purpose of this invention is to provide a multi-element organic waste anaerobic fermentation system to overcome the shortcomings of existing technologies.

[0009] The objective of this invention is achieved through the following technical solution: An anaerobic fermentation system for multi-element organic waste includes a first pretreatment device, a second pretreatment device, a hydrogen-producing and acid-producing fermentation reactor, a nanobubble generator, and a methanogenic fermentation reactor; the hydrogen-producing and acid-producing fermentation reactor includes a first inlet, a first outlet, and a first outlet; the methanogenic fermentation reactor includes a second inlet, a second outlet, and a second outlet. The first pretreatment device is connected to the first inlet, the first outlet is connected to the inlet of the nanobubble generator, and the outlet of the nanobubble generator, the first outlet, and the second pretreatment device are all connected to the second inlet. The first pretreatment device and the second pretreatment device are respectively used to pretreat easily degradable organic waste and difficult-to-degrade organic waste; The hydrogen-producing and acid-producing fermentation reactor is used to ferment pretreated easily degradable waste to produce hydrogen-producing and acid-producing gas and a first fermentation liquid. The nanobubble generator is used to prepare the hydrogen-containing tail gas into nanobubble water; The methanogenic fermentation reactor is used for methanogenic fermentation of the first fermentation liquid, the nanobubble water and the pretreated refractory organic waste, to produce methane and a second fermentation liquid.

[0010] Preferably, the anaerobic fermentation system provided by the present application further comprises a solid-liquid separation device; the solid-liquid separation device comprises a third feeding port, a liquid outlet and a third discharge port; the third feeding port is connected with the second discharge port; The solid-liquid separation device is used for solid-liquid separation of the second fermentation liquid, to produce tail liquid and tail residue; the tail liquid and the tail residue can be discharged through the liquid outlet and the third discharge port, respectively.

[0011] Preferably, the liquid outlet is connected with the second pretreatment device; the tail liquid is circulated and conveyed to the second pretreatment device.

[0012] Preferably, the anaerobic fermentation system provided by the present application further comprises a gas storage tank connected with the second gas outlet, used for storing the methane produced by the methanogenic fermentation reactor.

[0013] Preferably, the first pretreatment device is selected from one or more combinations of a crushing device, a filtering device, a centrifugal device and a pressing and deoiling device.

[0014] Preferably, the second pretreatment device is selected from one or more combinations of a crushing device, a heating device, a microwave device, an ultrasonic device and an aerobic degradation pretreatment device.

[0015] Preferably, the second pretreatment device is a crushing device and an aerobic degradation pretreatment device connected in sequence; the aerobic degradation pretreatment device is connected with the second feeding port.

[0016] Preferably, the liquid outlet is connected with the aerobic degradation pretreatment device.

[0017] Preferably, the anaerobic fermentation system provided by the present application further comprises a conveying pump, used for material conveying between device parts of the multi-element organic waste anaerobic fermentation system.

[0018] This application utilizes a differentiated treatment strategy based on the material degradation characteristics, combining the advantages of co-fermentation (carbon-nitrogen balance) and two-stage fermentation (easy to adjust). Raw materials are strategically allocated to the hydrogen- and acid-producing stages and the methanogenesis stage. In the hydrogen- and acid-producing fermentation reactor, only readily biodegradable organic waste with short hydrolysis times and easy acidification is used as the fermentation feedstock, enabling rapid hydrolysis to produce hydrogen and acid under low pH fermentation conditions. Then, in the methanogenesis fermentation reactor, the fermentation feedstock is a mixture of recalcitrant organic waste and readily biodegradable organic waste hydrogen- and acid-producing fermentation products. This ensures carbon- and nitrogen balance in the fermentation materials, while the readily biodegradable organic waste hydrogen- and acid-producing fermentation products promote the methane production rate. The fermentation rate of recalcitrant organic waste is also significantly increased under suitable fermentation conditions. Furthermore, the applicant discovered that the fermentation slag after hydrogen- and acid-producing from readily biodegradable organic waste has a synergistic effect with recalcitrant organic waste during methanogenesis, resulting in a higher methanogenesis yield. Meanwhile, this application utilizes nanobubble technology to recover the tail gas from the hydrogen-producing and acid-producing fermentation reactor for use in the methanogenic fermentation reactor, which can improve gas-liquid mass transfer efficiency, promote the hydrolysis of recalcitrant organic waste, and obtain higher methane production and energy recovery rate. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the anaerobic fermentation system provided in this application; Explanation of reference numerals in the attached figures: 1-First pretreatment device; 2-Second pretreatment device; 3-Hydrogen-producing and acid-producing fermentation reactor; 4-Nano bubble generator; 5-Methanogenic fermentation reactor; 6-Solid-liquid separation device; 7-Gas storage tank; 8-Transfer pump. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the application will now be described in detail with reference to the accompanying drawings.

[0021] The multi-element organic waste anaerobic fermentation system provided in this application, such as Figure 1 As shown, it includes a first pretreatment device 1, a second pretreatment device 2, a hydrogen-producing and acid-producing fermentation reactor 3, a nanobubble generator 4, and a methanogenic fermentation reactor 5; the hydrogen-producing and acid-producing fermentation reactor 3 includes a first feed inlet, a first gas outlet, and a first discharge outlet; the methanogenic fermentation reactor 5 includes a second feed inlet, a second gas outlet, and a second discharge outlet.

[0022] The first pretreatment device 1 and the second pretreatment device 2 are used to pretreat easily degradable organic waste and recalcitrant organic waste, respectively. The first pretreatment device 1 is also connected to a first feed inlet, and the pretreated easily degradable organic waste is transported to a hydrogen-producing and acid-producing fermentation reactor 3 for hydrogen-producing and acid-producing fermentation. The second pretreatment device 2 is also connected to a second feed inlet, and the pretreated recalcitrant organic waste is transported to a methanogenic fermentation reactor 5 for methanogenic fermentation.

[0023] The present application first divides the organic waste into easily degradable organic waste and difficult degradable organic waste, and respectively carries out pretreatment, wherein the easily degradable organic waste is generally low in carbon-nitrogen ratio, and includes but is not limited to one or more of kitchen waste, food processing waste, excrement, slaughter waste and domestic sewage sludge. After the pretreatment of the easily degradable organic matter, non-organic impurities are removed and the material properties are adjusted. Specifically, the first pretreatment device 1 can be selected from one or more combinations of a crushing device, a filtering device, a centrifugal device and a pressing deoiling device, and the easily degradable organic waste can be subjected to crushing, filtering, centrifugal and pressing deoiling treatment, so as to improve the homogeneity of the material and reduce the content of inhibitory substances.

[0024] The difficult degradable organic waste is generally high in carbon-nitrogen ratio, and includes but is not limited to one or more of crop straw, forestry waste, mushroom residue, coconut coir and landscaping waste. After the pretreatment of the difficult degradable organic waste, the cell structure thereof can be destroyed, and the biodegradability is improved. Specifically, the second pretreatment device 2 is selected from one or more combinations of a crushing device, a heating device, a microwave device, an ultrasonic device and an aerobic degradation pretreatment device, and is respectively used for crushing, heating, microwave, ultrasonic and aerobic degradation pretreatment of the difficult degradable organic waste. Since the difficult degradable organic waste such as straw is generally large in size and contains a lot of lignin, it is necessary to improve the biodegradability thereof, and therefore, the second pretreatment device provided by the present application is preferably a crushing device and an aerobic degradation pretreatment device connected in sequence, and the aerobic degradation pretreatment device is connected with the second feeding port. The difficult degradable organic waste is first crushed, and then inoculated with aerobic microorganisms for aerobic degradation pretreatment, so as to improve the biodegradability thereof. The material liquid after the aerobic degradation is transported to the methane-producing fermentation reactor 5 for methane-producing fermentation.

[0025] The first gas outlet is connected with the inlet end of the nano-bubble generator 4, and the first discharge port is connected with the second feeding port. The hydrogen-producing and acid-producing fermentation reactor 3 inoculates the pretreated easily degradable waste with hydrogen-producing and acid-producing microorganisms for hydrogen-producing and acid-producing fermentation, so as to produce hydrogen-containing tail gas and first fermentation material liquid, which are respectively transported to the nano-bubble generator 4 and the methane-producing fermentation reactor 5 through the first gas outlet and the first discharge port.

[0026] When the hydrogen-producing and acid-producing fermentation is carried out in the hydrogen-producing and acid-producing fermentation reactor 3, the fermentation pH is preferably controlled to be 5.0-6.0, and the fermentation products are mainly acetic acid, butyric acid and hydrogen, so as to ensure the directional production of hydrogen-containing products.

[0027] The inoculation substance of the hydrogen-producing and acid-producing fermentation reactor is preferably a mixture of sludge with hydrogen-producing and acid-producing microorganisms as the dominant flora after domestication and sludge after heat treatment with inactivated methanogens, so as to ensure the microbial activity and product directionality in the hydrogen-producing and acid-producing stage.

[0028] The outlet end of the nanobubble generator 4 is connected with the second feeding port. The hydrogen-containing tail gas produced by the hydrogen-producing and acid-producing fermentation reactor 3 is first transported to the nanobubble generator 4 to be made into nanobubble water, and then is transported to the methane-producing fermentation reactor 5 to be subjected to methane-producing fermentation. The nanobubble generator 4 can be made by using a high-pressure dissolving-decompression releasing method, a rotary fluid power cavitation method, an ultrasonic cavitation method, etc.

[0029] The first fermentation liquid, the nanobubble water and the pretreated refractory organic waste are transported to the methane-producing fermentation reactor 5 through the second feeding port, are inoculated with methane-producing microorganisms to be subjected to methane-producing fermentation, and produce methane and the second fermentation liquid, which are discharged through the second gas outlet and the second discharge outlet, respectively. The methane-producing microorganism inoculum is a sludge with methanogens as the dominant flora after domestication, which improves the methane conversion efficiency and stability.

[0030] The mixing ratio of the solid and liquid phase products produced by the hydrogen-producing and acid-producing fermentation reactor 3 to the pretreated refractory organic waste needs to be adjusted, so that the total carbon-nitrogen mass ratio of the mixed fermentation material is 20-30:1, so as to promote the carbon-nitrogen balance of the raw material and improve the substrate utilization efficiency. The mass percentage of the nanobubble water in the coupled fermentation material is 5%-20%, and a certain amount of nanobubble water can strengthen heat and mass transfer and provide substrates and key driving forces for hydrogen-alkane coupling.

[0031] The fermentation pH of the methane-producing fermentation reactor 5 is controlled to be 7.0-7.5 during methane-producing fermentation, so as to promote the efficient methane-producing process.

[0032] Generally, in the two-stage anaerobic fermentation process, the hydrogen-producing and acid-producing process has a short hydraulic retention period, the strains are acid-resistant and alkaline, while the methane-producing process has a long hydraulic retention period and poor stability. The easily degradable organic waste has the characteristics of short hydrolysis time and easy acidification, and is suitable for the hydrogen-producing and acid-producing fermentation reactor with short fermentation time and strong acid-resistant strains. The refractory material has a long hydrolysis time and is difficult to be effectively degraded in the hydrogen-producing and acid-producing fermentation reactor within a short time. In addition, the so-called two-stage anaerobic fermentation is only theoretically spatially isolated in the hydrogen-producing and acid-producing stage and the methane-producing stage, but in fact, the complete anaerobic fermentation system is still retained in the methane-producing fermentation reactor, so the refractory organic waste can still undergo the complete fermentation process and hydrolysis and methanation in the methane-producing fermentation reactor.

[0033] If only the easily degradable organic waste is used for two-stage fermentation, or only the recalcitrant organic waste is used for two-stage fermentation, firstly, single material will lead to acid ammonia inhibition affecting fermentation due to carbon and nitrogen imbalance (generally, the carbon and nitrogen ratio of anaerobic fermentation should be maintained at 20-30:1); secondly, the recalcitrant organic waste has a long hydrolysis time and a low gas production rate within a certain time. Although the traditional co-fermentation technology considers the problem of carbon and nitrogen balance, the material is still fermented in one reactor, ignoring the difference in the optimal fermentation conditions of different materials.

[0034] Therefore, based on the differentiated treatment strategy of material degradation characteristics, the present application combines the advantages of co-fermentation (carbon and nitrogen balance) and two-stage fermentation (convenient adjustment), and directs the allocation of raw materials to the hydrogen and acid production stage and the methane production stage. In the hydrogen and acid production fermentation reactor, only the easily degradable organic waste with short hydrolysis time and easy acidification is used as the fermentation raw material, which can be quickly hydrolyzed to produce hydrogen and acid under low pH fermentation conditions. Then the fermentation raw material of the methane production fermentation reactor uses a mixture of recalcitrant organic waste and easily degradable organic waste hydrogen and acid production fermentation product, which not only balances the carbon and nitrogen of the fermentation material, but also promotes the methane production rate of the easily degradable organic waste hydrogen and acid production fermentation product. The recalcitrant organic waste also has a significantly improved fermentation rate under suitable fermentation conditions. Moreover, the applicant has found that the fermentation liquid residue after the hydrogen and acid production of the easily degradable organic waste has a synergistic effect with the recalcitrant organic waste in the methane production fermentation process, which can obtain a higher methane production amount. At the same time, the present application recovers the tail gas of the hydrogen and acid production fermentation reactor for the methane production fermentation reactor using the nano bubble technology, which can improve the gas-liquid mass transfer efficiency, promote the hydrolysis of recalcitrant organic waste, and obtain higher methane production and energy recovery rate.

[0035] Therefore, the present application not only solves the problem of processing various types of organic waste, but also realizes the resource utilization of waste, which has significant environmental and economic benefits.

[0036] Preferably, the fermentation system provided by the present application further comprises a solid-liquid separation device 6; the solid-liquid separation device 6 comprises a third feeding port, a liquid outlet and a third discharge port; the third feeding port is connected with the second discharge port, and the second fermentation liquid produced by the methane production fermentation reactor 5 is transported to the solid-liquid separation device 6 through the second discharge port and the third feeding port. The solid-liquid separation device can use a filter press, a centrifuge, etc., which can separate the second fermentation liquid into tail liquid and tail residue, so as to facilitate targeted recycling, such as making organic fertilizer from the tail residue.

[0037] Further preferably, the liquid outlet is connected with the second pretreatment device 2; the tail liquid is circulated to the second pretreatment device 2. Since the moisture content of the difficultly degradable organic waste needs to be adjusted when the pretreatment is performed, such as the moisture content of about 60% when the aerobic degradation pretreatment is performed, therefore, the tail liquid can be transported to the second pretreatment device 2 to adjust the moisture content of the difficultly degradable organic waste, so as to realize the recycling of the tail liquid.

[0038] Preferably, the anaerobic fermentation system provided by the application further comprises a gas storage tank 7 connected with the second gas outlet, for storing the methane produced by the methanogenic fermentation reactor 5.

[0039] Preferably, the anaerobic fermentation system provided by the application further comprises a delivery pump 8, for delivering materials between the parts of the system.

[0040] Embodiment 1 The anaerobic fermentation system as shown in Figure 1 is used to produce methane, wherein the first pretreatment device comprises a first crushing device and a deoiling device, and the second pretreatment device comprises a second crushing device and an aerobic degradation pretreatment device, and the specific operation steps are as follows: S1. Collect corn stalks (carbon-nitrogen ratio 44:1), and mechanically crush them to an average particle size of less than 20 mm by using the second crushing device; S2. Collect kitchen waste from a canteen (carbon-nitrogen ratio 15:1), and mainly use vegetables, meat and rice as raw materials, remove plastics, metals and other impurities, and then mechanically crush and deoiling treat them by using the first crushing device and the deoiling device; S3. Adjust the moisture content of the crushed corn stalks to 60% by using the aerated biogas slurry, inoculate sludge from a sewage plant in the aerobic degradation pretreatment device to perform aerobic degradation, and end the aerobic degradation when the pH of the material liquid rises.

[0041] S4. Send the kitchen waste treatment liquid obtained in step S2 into the hydrogen-producing and acid-producing fermentation reactor 3, inoculate a mixture (mass ratio 3:1) of sludge with acclimated hydrogen-producing and acid-producing microorganisms as the dominant flora and sludge with inactivated methanogens after heat treatment, heat the reactor, and maintain the heating temperature at about 35℃; monitor the VFAs concentration of the fermentation liquid in the reactor in the early stage of fermentation, take acetic acid, butyric acid and hydrogen as the main target products, adjust the feed load and hydraulic retention period of the reactor, determine the feed load of this embodiment as 4.5 g-VS / (L·d), and the hydraulic retention period as 4d, and regularly detect the pH value of the fermentation liquid in the reactor, control the fermentation pH to be 5.0-6.0, add an appropriate amount of citric acid solution when the pH is >6, and add sodium bicarbonate solution when the pH is <5.0.

[0042] S5. Collect the fermentation gas of step S4, and pass it through water purification to enter the nanobubble generator 4 at a low flow rate, to be prepared into nanobubble water by releasing pressure at 0.5 MPa through a microporous membrane with a specific pore size of 100 nm; S6. Send the nanobubble water obtained in step 5, the pretreated corn stalk liquid of step S3, and the hydrogen-producing fermentation liquid of step S4 into the methane-producing fermentation reactor 5, then inoculate with methanogenic activated sludge, and perform anaerobic fermentation under the condition of 35°C. The feeding amount of nanobubble water is 10% of the total feeding mass, and the feeding amount of corn stalk liquid is such that the carbon-nitrogen ratio in the mixed total feeding liquid is 25:1. The methane production is monitored in the initial stage of fermentation, and the corn stalk liquid feeding load (the hydrogen-producing fermentation liquid of step S4 is all sent into the methane-producing fermentation reactor 5) and the hydraulic retention period are adjusted to determine that the corn stalk liquid feeding load in this stage is 1.1 g-VS / (L·d) (it is detected that the carbon-nitrogen ratio in the total feeding liquid under this condition is maintained between 20-30:1), and the hydraulic retention period is 20 d. The pH value of the fermentation liquid in the reactor is detected regularly, and the fermentation pH is controlled to be 7.0-7.5. When the pH > 7.5, an appropriate amount of citric acid solution is added; when the pH < 7.0, sodium bicarbonate solution is added.

[0043] S7. Collect the fermentation gas of step S6, and it is detected that the methane content in the biogas is about 57%, and the methane production is about 322 mL / g-VS. The fermentation material of step S6 is collected, and is separated into biogas residue and biogas liquid through solid-liquid separation, and the biogas liquid is circulated and delivered to step S3 after aeration for pretreatment.

[0044] Comparative Example 1 This comparative example only includes a methane-producing fermentation reactor compared with the example, and the pretreated corn stalk and kitchen waste are directly sent into the methane-producing fermentation reactor (inoculated with methanogenic activated sludge) for fermentation, and the fermentation conditions are the same as those of Example 1 (the fermentation temperature is 35°C, the feeding amount of corn stalk liquid is such that the carbon-nitrogen ratio in the mixed total feeding liquid is 25:1, and the fermentation pH is controlled to be 7.0-7.5).

[0045] The fermentation gas is collected, and it is detected that the methane content in the biogas is about 55%, and the methane production is about 261 mL / g-VS. This result proves that the methane production is significantly reduced when the easily degradable organic waste is not subjected to hydrogen-producing and acid-producing fermentation alone.

[0046] In industrial production, when corn stalks are used in traditional anaerobic fermentation, due to the complex cellulose structure and low degradation rate, the methane content is generally about 50%, and the production is close to 210 mL / g-VS; the system of the application can not only improve the methane production and methane concentration of straw and other difficult-to-degrade biomass in anaerobic fermentation, but also solve the problems of ammonia inhibition in the process of traditional single raw material anaerobic fermentation and acid inhibition caused by straw.

[0047] While the preferred embodiments of the application have been described, additional variations and modifications can be made to these embodiments by those skilled in the art once they have the benefit of the present disclosure without departing from the spirit and scope of the application. Accordingly, it is intended that the appended claims include all such variations and modifications as fall within the scope of the present application. It is apparent that those skilled in the art can modify and adapt the present application in various ways without departing from the spirit and scope of the present application. It is therefore intended that the present application encompass all such modifications and variations as fall within the scope of the claims and their equivalents.

Claims

1. A multi-component organic waste anaerobic fermentation system, characterized by, The system comprises a first pretreatment device, a second pretreatment device, a hydrogen and acid producing fermentation reactor, a nanobubble generator and a methane producing fermentation reactor; the hydrogen and acid producing fermentation reactor comprises a first feeding port, a first gas outlet and a first discharging port; the methane producing fermentation reactor comprises a second feeding port, a second gas outlet and a second discharging port; The first pretreatment device is connected with the first feeding port, the first gas outlet is connected with the inlet end of the nanobubble generator, the outlet end of the nanobubble generator, the first discharging port and the second pretreatment device are all connected with the second feeding port; The first pretreatment device and the second pretreatment device are respectively used for pretreating easily degradable organic waste and hardly degradable organic waste; The hydrogen and acid producing fermentation reactor is used for hydrogen and acid producing fermentation of the pretreated easily degradable waste, to produce hydrogen-containing tail gas and a first fermentation liquid; The nanobubble generator is used for preparing the hydrogen-containing tail gas into nanobubble water; The methane producing fermentation reactor is used for methane producing fermentation of the first fermentation liquid, the nanobubble water and the pretreated hardly degradable organic waste, to produce methane and a second fermentation liquid.

2. The system according to claim 1, further comprising a solid-liquid separation device; the solid-liquid separation device comprises a third feeding port, a liquid outlet and a third discharging port; the third feeding port is connected with the second discharging port; The solid-liquid separation device is used for solid-liquid separation of the second fermentation liquid, to produce tail liquid and tail residue; the tail liquid and the tail residue can be discharged through the liquid outlet and the third discharging port respectively.

3. The system according to claim 2, wherein the liquid outlet is connected with the second pretreatment device; the tail liquid is circulated and delivered to the second pretreatment device.

4. The system according to claim 1, further comprising a gas storage tank connected with the second gas outlet, used for storing the methane produced by the methane producing fermentation reactor.

5. The system according to claim 1, wherein the first pretreatment device is selected from one or more combinations of a crushing device, a filtering device, a centrifugal device and a pressing and oil-removing device.

6. The system according to claim 1, wherein the second pretreatment device is selected from one or more combinations of a crushing device, a heating device, a microwave device, an ultrasonic device and an aerobic degradation pretreatment device.

7. The system according to claim 3, wherein the second pretreatment device is a crushing device and an aerobic degradation pretreatment device connected in sequence; the aerobic degradation pretreatment device is connected with the second feeding port.

8. The system according to claim 7, wherein the liquid outlet is connected with the aerobic degradation pretreatment device.

9. The system according to claim 1, ​ ​ ​ ​ ​ ​ ​ A delivery pump is also included for material delivery between various parts of the system.

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