System for alleviating ammonia inhibition of anaerobic digestion of medium-high temperature food waste by negative pressure coupling biogas backflow

Abstract

The utility model relates to a system for relieving ammonia inhibition in anaerobic digestion of medium-high temperature kitchen waste, and relates to a system for relieving ammonia inhibition in anaerobic digestion of medium-high temperature kitchen waste. The utility model is to solve the technical problems of low methane yield, high cost and ammonia nitrogen accumulation in the anaerobic digestion process of kitchen waste. The utility model draws negative pressure at the top of the anaerobic digestion tank, has low energy consumption, and can effectively reduce the ammonia nitrogen concentration of the liquid phase part and relieve the inhibition of methanogens. In addition, a small amount of H2 exists in biogas, which can generate methane under the action of hydrogen-utilizing methanogens after being recycled back to the anaerobic digestion tank, thereby increasing the proportion of methane in biogas. The utility model reduces the ammonia nitrogen partial pressure of the gas part in the anaerobic digestion tank, relieves ammonia inhibition in the system, and simultaneously realizes resource recycling, biogas purification and efficiency improvement of biogas production, thereby providing new technical support for improving the medium-high temperature anaerobic digestion of high-protein materials represented by kitchen waste.

Description

Technical Field

[0001] This utility model relates to a system for alleviating ammonia inhibition during the anaerobic digestion of medium- and high-temperature kitchen waste. Background Technology

[0002] my country's annual output of food waste has exceeded 50 million tons, with volatile solids (VS) content reaching nearly 90%, indicating enormous potential for resource utilization. Anaerobic digestion, as a low-cost and high-energy-recovery technology, utilizes microorganisms such as hydrolytic acidifying bacteria and methanogenic archaea to convert carbohydrates, proteins, and lipids in food waste into biogas, primarily methane, while effectively linking the upstream and downstream industrial chains of food waste resource utilization. Typically, during the anaerobic digestion of medium- and high-temperature food waste, the concentration of free ammonia produced by protein degradation easily exceeds 4000 mg / L, leading to the inhibition of methanogenic bacteria activity and a 30%–50% decrease in methane yield. Traditional solutions such as dilution methods require large amounts of water, while adsorption methods (activated carbon, zeolite) are costly and difficult to regenerate. Existing patents (such as CN205974214U) propose biogas circulation and stirring technology, but do not solve the problem of ammonia nitrogen accumulation; patent CN106277435A uses chemical precipitation to recover ammonia, but the process is complex and prone to introducing secondary pollution. Utility Model Content

[0003] This invention aims to solve the technical problems of low methane yield, high cost, and ammonia nitrogen accumulation in the existing anaerobic digestion process of kitchen waste, and provides a system for mitigating ammonia inhibition in the anaerobic digestion of medium- and high-temperature kitchen waste by providing negative pressure coupled biogas reflux.

[0004] The system for mitigating ammonia inhibition during anaerobic digestion of medium- and high-temperature kitchen waste by negative pressure coupling biogas reflux is composed of an anaerobic digester 1, a vacuum pump 2, a gas buffer tank 3, an acid washing container 4, an alkaline washing container 5, a dehydration container 6, a gas mixing tank 7, a circulation pump 8, and a nano aerator 9.

[0005] The anaerobic digester 1 is equipped with a stirring device 1-1, a nano-aeration head 9 is installed at the bottom of the inner cavity of the anaerobic digester 1, and a material feeding port is installed on the side wall of the anaerobic digester 1; a temperature sensor and a pH probe are installed on the inner wall of the anaerobic digester 1; the top side of the anaerobic digester 1 is connected to the air inlet of the vacuum pump 2, and the outlet of the vacuum pump 2 is connected to the bottom of the gas buffer tank 3; a cyclone separator is installed at the top of the inner cavity of the gas buffer tank 3, and the volume of the gas buffer tank 3 is 10% of that of the anaerobic digester 1;

[0006] The pickling container 4 has a first air inlet pipe 4-2 at the top center, which extends downward to the lower middle part of the pickling container 4. A first air outlet pipe 4-3 is also provided at the top of the pickling container 4. A first gas-liquid separation membrane 4-1 is provided in the upper middle part of the inner wall of the pickling container 4. Multiple first spray pipes 4-4 are provided below the first gas-liquid separation membrane 4-1, with a main valve at the front end of each first spray pipe 4-4, which communicates with external acid. A first packing layer 4-5 is provided in the middle of the inner wall of the pickling container 4, located below the first spray pipes 4-4. The bottom 4-6 of the pickling container 4 is a sedimentation collection area with a conical structure. The top outlet of the gas buffer tank 3 is connected to the first air inlet pipe 4-2 at the top of the pickling container 4, and a gas composition analyzer is provided at the top outlet of the gas buffer tank 3.

[0007] The alkaline washing container 5 has a second air inlet pipe 5-2 at the top center, which extends downwards to the lower middle part of the container. A second air outlet pipe 5-3 is also provided at the top of the container. A second gas-liquid separation membrane 5-1 is provided in the upper middle part of the inner wall of the container. Multiple second spray pipes 5-4 are provided below the second gas-liquid separation membrane 5-1, with a main valve at the front end of each spray pipe 5-4, which communicates with the external alkaline solution. A second packing layer 5-5 is provided in the middle of the inner wall of the container, located below the second spray pipes 5-4. The bottom 5-6 of the container is a drain outlet with a conical structure. The first air outlet pipe 4-3 of the acid washing container 4 is connected to the second air inlet pipe 5-2 at the top of the alkaline washing container 5.

[0008] The dehydration container 6 has a third air inlet pipe 6-2 at the top center and a waste gas outlet pipe 6-3 at the top. A silica gel layer 6-1 is provided in the middle of the inner wall of the dehydration container 6. The bottom of the dehydration container 6 has a hot air inlet 6-4 and a purified biogas outlet 6-5. A temperature sensor is provided on the hot air inlet 6-4 and a humidity sensor is provided on the purified biogas outlet 6-5. The second air outlet pipe 5-3 of the alkaline washing container 5 is connected to the third air inlet pipe 6-2 at the top of the dehydration container 6.

[0009] The gas mixing tank 7 is uniformly equipped with multiple vertically arranged baffles 7-1. The air inlet and air outlet are located at the two ends of the gas mixing tank 7, respectively. An oxygen inlet pipe 7-2 is provided at the end near the air inlet. The purified biogas outlet 6-5 of the dehydration container 6 is connected to the air inlet of the gas mixing tank 7. The air outlet of the gas mixing tank 7 is connected to the nano-aeration head 9 at the bottom of the anaerobic digester 1 through the circulation pump 8.

[0010] The system is also equipped with a controller. The signal input terminal of the controller is connected to the signal output terminals of all temperature sensors, pH probes, gas analyzers and humidity sensors. The signal output terminal of the controller is connected to the signal input terminal of the main valve at the front end of the stirring device 1-1, vacuum pump 2, circulation pump 8, first spray pipe 4-4 and second spray pipe 5-4.

[0011] The usage method and working principle of this utility model's negative pressure coupled biogas reflux system for alleviating ammonia inhibition during the anaerobic digestion of medium- and high-temperature kitchen waste are as follows:

[0012] 1. System Start-up: Inject kitchen waste and anaerobic sludge into the material inlet of anaerobic digester 1, with a VS ratio of 1:1; then start the stirring device 1-1 at a speed of 20 rpm to 40 rpm; set the internal temperature of anaerobic digester 1 to 37 to 55°C, add acid and alkali agents until the pH is 6.8 to 7.5, and feed and discharge materials according to a sludge retention time of 40 days;

[0013] 2. Negative Pressure Extraction and Biogas Purification: Vacuum pump 2 is started (vacuum degree 50000Pa±5%, when ammonia nitrogen concentration exceeds 3000mg / L, the extraction rate is increased to 120% of the rated value). Biogas enters the acid washing container 4 through gas buffer tank 3. The gas buffer tank 3 has a built-in cyclone separator 3-1 to remove entrained particulate matter, achieving a particulate matter removal rate of ≥95% in the biogas. In the acid washing container 4, sulfuric acid (10%–20% sulfuric acid solution by mass concentration) is sprayed through the first spray pipe 4-4. Ammonia reacts with sulfuric acid to form ammonium sulfate crystals (particle size 50μm–200μm), achieving an ammonia removal rate of ≥95%. The bottom 4-6 is for sediment collection. The collection area is used to recover ammonium sulfate crystals for use as fertilizer; the first gas-liquid separation membrane 4-1 is made of PTFE material with a pore size of 0.2μm, used to intercept acid mist droplets and tiny crystals; the middle part is the gas-liquid reaction zone, filled with PP material packing to increase the gas-liquid contact area. The biogas after ammonia removal enters the alkaline washing container 5, and is sprayed with NaOH solution (5% to 10% sodium hydroxide solution by mass concentration) through the second spray pipe 5-4. Hydrogen sulfide reacts with NaOH to generate Na2S, and carbon dioxide partially dissolves in the alkaline solution; the biogas after desulfurization enters the dehydration container 6, where the silica gel layer 6-1 adsorbs moisture, and the humidity of the biogas exiting the purified biogas outlet 6-5 is ≤5%;

[0014] 3. Biogas Recirculation and Reaction Enhancement: Oxygen is injected into the gas mixing tank 7 through the oxygen inlet pipe 7-2 at a flow rate of 0.1% to 0.5% of the biogas recirculation flow rate. This is used to promote the metabolic activity of hydrogen-producing methanogens, recirculate residual hydrogen to produce methanogens, and increase the methane concentration in the biogas. The purified biogas is mixed with trace amounts of oxygen in the gas mixing tank 7. The gas mixing tank 7 is equipped with baffles 7-1 to ensure that the biogas residence time is ≥30s. After being pressurized to 0.1 to 0.3MPa by the circulating pump 8, it is released into the anaerobic digester 1 through the nano-aerator head 9. The bubble diameter is ≤100nm, and the gas-liquid volume mixing ratio is 1:(2 to 3). The circulating H2 reacts with CO2 in the tank under the action of hydrogen-producing methanogens to produce methane.

[0015] 4. Intelligent Control: The gas composition analyzer uploads data every 30 minutes, and the controller dynamically adjusts the frequency of vacuum pump 2, the acceleration rate of acid and alkali solution dosing, and the oxygen injection volume of oxygen inlet pipe 7-2; when the methane purity in the top outlet of gas buffer tank 3 is >70%, 85% of the biogas is diverted to the gas storage tank (outside the system, not shown in the figure) for resource recovery, and the remaining 15% is returned to the acid washing container 4; when the methane purity in the top outlet of gas buffer tank 3 is ≤70%, all of it is returned to the acid washing container 4 for processing;

[0016] An alarm will be triggered and the machine will automatically shut down if the following conditions are detected: the sulfuric acid concentration in pickling container 4 is below 5%; the pH value of alkaline washing container 5 exceeds 12.5; or the humidity of dehydration container 6 exceeds 15%.

[0017] 5. Maintenance strategy: Regenerate the desiccant silica gel layer 6-1 every 72 hours by introducing hot air into the hot air inlet 6-4 and baking at 180°C for 2 hours.

[0018] This invention reduces the ammonia nitrogen concentration in the system from 4000 mg / L to below 3000 mg / L by adjusting the solid-liquid distribution of ammonia, while increasing the methane yield by 20%–30%. The system integrates real-time monitoring and intelligent adjustment of gas composition, as well as the resource recovery of hydrogen sulfide. It is suitable for medium- and high-temperature (37℃–55℃) anaerobic digestion of high-solids-content (TS≥15%) food waste, and features low energy consumption (overall energy consumption reduced by 30%) and a high degree of automation.

[0019] This invention employs a negative pressure method at the top of the anaerobic digester 1, which avoids the problem of excessive energy consumption in the traditional gas extraction method and can effectively reduce the ammonia nitrogen concentration in the liquid phase, thus alleviating the inhibitory effect on methanogens. In addition, since there is a small amount of H2 in the biogas, after it is circulated back to the anaerobic digester 1, it can react with CO2 to generate methane under the action of hydrogenophilic methanogens, thereby increasing the proportion of methane in the biogas.

[0020] This invention alleviates ammonia inhibition in the system by reducing the partial pressure of ammonia nitrogen in the gas section of the anaerobic digester 1, while simultaneously achieving resource recovery, biogas purification, and improved biogas production efficiency, providing new technical support for further improving the high-temperature anaerobic digestion of high-protein materials such as kitchen waste.

[0021] Compared with the prior art, the beneficial effects of this utility model include:

[0022] 1. Ammonia nitrogen control: Through gas-liquid balance regulation, the ammonia nitrogen concentration is reduced from above 4000 mg / L to below 3000 mg / L, and the total ammonia nitrogen removal rate is ≥25%;

[0023] 2. Hydrogen sulfide removal: The hydrogen sulfide content is reduced from 2000 ppm to below 20 ppm, reducing the difficulty of subsequent natural gas conversion;

[0024] 3. Enhanced Methane Production: By mitigating ammonia inhibition and enhancing the hydroxylamine-producing (HMP) pathway, the CO2 concentration in the harvested biogas is ≥70%, and the methane yield is increased from 0.35 m³ / s. 3 / kg VS increased to 0.40m 3 / kg VS;

[0025] 4. System stability: After 90 days of continuous operation, the performance of key components (aerator head, vacuum pump) decreases by less than 5%. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a system for mitigating ammonia inhibition during the anaerobic digestion of medium- and high-temperature kitchen waste using negative pressure coupled biogas reflux as a specific implementation method.

[0027] Figure 2 This is a schematic diagram of the pickling container 4 in the first specific embodiment;

[0028] Figure 3 This is a schematic diagram of the alkaline washing container 5 according to specific implementation method one;

[0029] Figure 4 This is a schematic diagram of the dehydration container 6 in the first specific embodiment. Detailed Implementation

[0030] Specific Implementation Method 1: This implementation method is a system for mitigating ammonia inhibition during the anaerobic digestion of medium- and high-temperature kitchen waste through negative pressure coupled biogas reflux, such as... Figures 1-4 As shown, it is specifically composed of an anaerobic digester 1, a vacuum pump 2, a gas buffer tank 3, an acid washing container 4, an alkaline washing container 5, a dehydration container 6, a gas mixing tank 7, a circulation pump 8, and a nano aeration head 9.

[0031] The anaerobic digester 1 is equipped with a stirring device 1-1, a nano-aeration head 9 is installed at the bottom of the inner cavity of the anaerobic digester 1, and a material feeding port is installed on the side wall of the anaerobic digester 1; a temperature sensor and a pH probe are installed on the inner wall of the anaerobic digester 1; the top side of the anaerobic digester 1 is connected to the air inlet of the vacuum pump 2, and the outlet of the vacuum pump 2 is connected to the bottom of the gas buffer tank 3; a cyclone separator is installed at the top of the inner cavity of the gas buffer tank 3, and the volume of the gas buffer tank 3 is 10% of that of the anaerobic digester 1;

[0032] The pickling container 4 has a first air inlet pipe 4-2 at the top center, which extends downward to the lower middle part of the pickling container 4. A first air outlet pipe 4-3 is also provided at the top of the pickling container 4. A first gas-liquid separation membrane 4-1 is provided in the upper middle part of the inner wall of the pickling container 4. Multiple first spray pipes 4-4 are provided below the first gas-liquid separation membrane 4-1, with a main valve at the front end of each first spray pipe 4-4, which communicates with external acid. A first packing layer 4-5 is provided in the middle of the inner wall of the pickling container 4, located below the first spray pipes 4-4. The bottom 4-6 of the pickling container 4 is a sedimentation collection area with a conical structure. The top outlet of the gas buffer tank 3 is connected to the first air inlet pipe 4-2 at the top of the pickling container 4, and a gas composition analyzer is provided at the top outlet of the gas buffer tank 3.

[0033] The alkaline washing container 5 has a second air inlet pipe 5-2 at the top center, which extends downwards to the lower middle part of the container. A second air outlet pipe 5-3 is also provided at the top of the container. A second gas-liquid separation membrane 5-1 is provided in the upper middle part of the inner wall of the container. Multiple second spray pipes 5-4 are provided below the second gas-liquid separation membrane 5-1, with a main valve at the front end of each spray pipe 5-4, which communicates with the external alkaline solution. A second packing layer 5-5 is provided in the middle of the inner wall of the container, located below the second spray pipes 5-4. The bottom 5-6 of the container is a drain outlet with a conical structure. The first air outlet pipe 4-3 of the acid washing container 4 is connected to the second air inlet pipe 5-2 at the top of the alkaline washing container 5.

[0034] The dehydration container 6 has a third air inlet pipe 6-2 at the top center and a waste gas outlet pipe 6-3 at the top. A silica gel layer 6-1 is provided in the middle of the inner wall of the dehydration container 6. The bottom of the dehydration container 6 has a hot air inlet 6-4 and a purified biogas outlet 6-5. A temperature sensor is provided on the hot air inlet 6-4 and a humidity sensor is provided on the purified biogas outlet 6-5. The second air outlet pipe 5-3 of the alkaline washing container 5 is connected to the third air inlet pipe 6-2 at the top of the dehydration container 6.

[0035] The gas mixing tank 7 is uniformly equipped with multiple vertically arranged baffles 7-1. The air inlet and air outlet are located at the two ends of the gas mixing tank 7, respectively. An oxygen inlet pipe 7-2 is provided at the end near the air inlet. The purified biogas outlet 6-5 of the dehydration container 6 is connected to the air inlet of the gas mixing tank 7. The air outlet of the gas mixing tank 7 is connected to the nano-aeration head 9 at the bottom of the anaerobic digester 1 through the circulation pump 8.

[0036] The system is also equipped with a controller. The signal input terminal of the controller is connected to the signal output terminals of all temperature sensors, pH probes, gas analyzers and humidity sensors. The signal output terminal of the controller is connected to the signal input terminal of the main valve at the front end of the stirring device 1-1, vacuum pump 2, circulation pump 8, first spray pipe 4-4 and second spray pipe 5-4.

[0037] The usage method and working principle of the negative pressure coupled biogas reflux system for alleviating ammonia inhibition in the anaerobic digestion of medium- and high-temperature kitchen waste in this embodiment are as follows:

[0038] 1. System Start-up: Inject kitchen waste and anaerobic sludge into the material inlet of anaerobic digester 1, with a VS ratio of 1:1; then start the stirring device 1-1 at a speed of 20 rpm to 40 rpm; set the internal temperature of anaerobic digester 1 to 37 to 55°C, add acid and alkali agents until the pH is 6.8 to 7.5, and feed and discharge materials according to a sludge retention time of 40 days;

[0039] 2. Negative Pressure Extraction and Biogas Purification: Vacuum pump 2 is started (vacuum degree 50000Pa±5%, when ammonia nitrogen concentration exceeds 3000mg / L, the extraction rate is increased to 120% of the rated value). Biogas enters the acid washing container 4 through gas buffer tank 3. The gas buffer tank 3 has a built-in cyclone separator 3-1 to remove entrained particulate matter, achieving a particulate matter removal rate of ≥95% in the biogas. In the acid washing container 4, sulfuric acid (10%–20% sulfuric acid solution by mass concentration) is sprayed through the first spray pipe 4-4. Ammonia reacts with sulfuric acid to form ammonium sulfate crystals (particle size 50μm–200μm), achieving an ammonia removal rate of ≥95%. The bottom 4-6 is for sediment collection. The collection area is used to recover ammonium sulfate crystals for use as fertilizer; the first gas-liquid separation membrane 4-1 is made of PTFE material with a pore size of 0.2μm, used to intercept acid mist droplets and tiny crystals; the middle part is the gas-liquid reaction zone, filled with PP material packing to increase the gas-liquid contact area. The biogas after ammonia removal enters the alkaline washing container 5, and is sprayed with NaOH solution (5% to 10% sodium hydroxide solution by mass concentration) through the second spray pipe 5-4. Hydrogen sulfide reacts with NaOH to generate Na2S, and carbon dioxide partially dissolves in the alkaline solution; the biogas after desulfurization enters the dehydration container 6, where the silica gel layer 6-1 adsorbs moisture, and the humidity of the biogas exiting the purified biogas outlet 6-5 is ≤5%;

[0040] 3. Biogas Recirculation and Reaction Enhancement: Oxygen is injected into the gas mixing tank 7 through the oxygen inlet pipe 7-2 at a flow rate of 0.1% to 0.5% of the biogas recirculation flow rate. This is used to promote the metabolic activity of hydrogen-producing methanogens, recirculate residual hydrogen to produce methanogens, and increase the methane concentration in the biogas. The purified biogas is mixed with trace amounts of oxygen in the gas mixing tank 7. The gas mixing tank 7 is equipped with baffles 7-1 to ensure that the biogas residence time is ≥30s. After being pressurized to 0.1 to 0.3MPa by the circulating pump 8, it is released into the anaerobic digester 1 through the nano-aerator head 9. The bubble diameter is ≤100nm, and the gas-liquid volume mixing ratio is 1:(2 to 3). The circulating H2 reacts with CO2 in the tank under the action of hydrogen-producing methanogens to produce methane.

[0041] 4. Intelligent Control: The gas composition analyzer uploads data every 30 minutes, and the controller dynamically adjusts the frequency of vacuum pump 2, the acceleration rate of acid and alkali solution dosing, and the oxygen injection volume of oxygen inlet pipe 7-2; when the methane purity in the top outlet of gas buffer tank 3 is >70%, 85% of the biogas is diverted to the gas storage tank (outside the system, not shown in the figure) for resource recovery, and the remaining 15% is returned to the acid washing container 4; when the methane purity in the top outlet of gas buffer tank 3 is ≤70%, all of it is returned to the acid washing container 4 for processing;

[0042] An alarm will be triggered and the machine will automatically shut down if the following conditions are detected: the sulfuric acid concentration in pickling container 4 is below 5%; the pH value of alkaline washing container 5 exceeds 12.5; or the humidity of dehydration container 6 exceeds 15%.

[0043] 5. Maintenance strategy: Regenerate the desiccant silica gel layer 6-1 every 72 hours by introducing hot air into the hot air inlet 6-4 and baking at 180°C for 2 hours.

[0044] This implementation reduces the ammonia nitrogen concentration in the system from 4000 mg / L to below 3000 mg / L by adjusting the solid-liquid distribution of ammonia, thereby increasing the methane yield by 20%–30%. The system integrates real-time monitoring of gas composition, intelligent adjustment, and hydrogen sulfide resource recovery. It is suitable for medium- and high-temperature (37°C–55°C) anaerobic digestion of high-solids-content (TS≥15%) food waste, and features low energy consumption (overall energy consumption reduced by 30%) and a high degree of automation.

[0045] This embodiment employs a negative pressure method at the top of the anaerobic digester 1, which avoids the problem of excessive energy consumption in the traditional gas extraction method and can effectively reduce the ammonia nitrogen concentration in the liquid phase, alleviating the inhibitory effect on methanogens. In addition, the biogas contains a small amount of H2, which, after being circulated back to the anaerobic digester 1, can react with CO2 to generate methane under the action of hydrogenophilic methanogens, thereby increasing the proportion of methane in the biogas.

[0046] This embodiment reduces the partial pressure of ammonia nitrogen in the gaseous portion of the anaerobic digester 1, thereby alleviating ammonia inhibition in the system. At the same time, it achieves resource recovery, biogas purification, and improved biogas production efficiency, providing new technical support for further improving the high-temperature anaerobic digestion of high-protein materials such as kitchen waste.

[0047] Compared with the prior art, the beneficial effects of this embodiment include:

[0048] 1. Ammonia nitrogen control: Through gas-liquid balance regulation, the ammonia nitrogen concentration is reduced from above 4000 mg / L to below 3000 mg / L, and the total ammonia nitrogen (TAN) removal rate is ≥25%;

[0049] 2. Hydrogen sulfide removal: The hydrogen sulfide content is reduced from 2000 ppm to below 20 ppm, reducing the difficulty of subsequent natural gas conversion;

[0050] 3. Enhanced Methane Production: By mitigating ammonia inhibition and enhancing the hydroxylamine-producing (HMP) pathway, the CO2 concentration in the harvested biogas is ≥70%, and the methane yield is increased from 0.35 m³ / s. 3 / kg VS increased to 0.40m 3 / kg VS;

[0051] 4. System stability: After 90 days of continuous operation, the performance of key components (aerator head, vacuum pump) decreases by less than 5%.

[0052] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the pore size of the nano-aeration head 9 is 50nm to 100nm. Everything else is the same as in Specific Implementation Method One.

[0053] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the pore size of the first gas-liquid separation membrane 4-1 is 0.1μm to 0.5μm. Everything else is the same as in Specific Implementation Method 1 or 2.

[0054] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the pore size of the second gas-liquid separation membrane 5-1 is 0.1 μm to 0.5 μm. Everything else is the same as in Specific Implementation Methods One to Three.

[0055] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method Four in that the vacuum pump 2 is a dry screw vacuum pump. Everything else is the same as in Specific Implementation Method Four.

[0056] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Five in that the filling height standard for the first filler layer 4-5 and the second filler layer 5-5 is: H f / D≥0.8, where H fWhere is the packing height and D is the diameter of the packing column; both units are the same. Everything else is the same as in Specific Implementation Method Five.

Claims

1. A system for alleviating ammonia inhibition in anaerobic digestion of medium-high temperature kitchen waste by negative pressure coupling biogas backflow, characterized in that The system for mitigating ammonia inhibition in the anaerobic digestion of medium- and high-temperature kitchen waste by negative pressure coupling biogas reflux consists of an anaerobic digester (1), a vacuum pump (2), a gas buffer tank (3), an acid washing container (4), an alkaline washing container (5), a dehydration container (6), a gas mixing tank (7), a circulation pump (8), and a nano aerator (9). The anaerobic digester (1) is equipped with a stirring device (1-1), a nano-aeration head (9) is installed at the bottom of the inner cavity of the anaerobic digester (1), and a material feeding port is installed on the side wall of the anaerobic digester (1); a temperature sensor and a pH probe are installed on the inner wall of the anaerobic digester (1); the top side of the anaerobic digester (1) is connected to the air inlet of the vacuum pump (2), and the outlet of the vacuum pump (2) is connected to the bottom of the gas buffer tank (3); a cyclone separator is installed at the top of the inner cavity of the gas buffer tank (3), and the volume of the gas buffer tank (3) is 10% of that of the anaerobic digester (1); A first air inlet pipe (4-2) is provided at the center of the top of the pickling container (4), and the first air inlet pipe (4-2) extends downward to the lower middle part of the pickling container (4). A first air outlet pipe (4-3) is also provided at the top of the pickling container (4). A first gas-liquid separation membrane (4-1) is provided in the upper middle part of the inner wall of the pickling container (4). A plurality of first spray pipes (4-4) are provided below the first gas-liquid separation membrane (4-1). A main valve is provided at the front end of the first spray pipe (4-4). The first spray pipe (4-4) is connected to the external acid solution; a first packing layer (4-5) is provided in the middle of the inner wall of the pickling container (4), and the first packing layer (4-5) is located below the first spray pipe (4-4); the bottom (4-6) of the pickling container (4) is a sedimentation collection area, which is a conical structure; the top outlet of the gas buffer tank (3) is connected to the top first air inlet pipe (4-2) of the pickling container (4), and a gas composition analyzer is provided at the top outlet of the gas buffer tank (3); A second air inlet pipe (5-2) is provided at the center of the top of the alkaline washing container (5), and the second air inlet pipe (5-2) extends downward to the lower middle part of the alkaline washing container (5). A second air outlet pipe (5-3) is also provided at the top of the alkaline washing container (5). A second gas-liquid separation membrane (5-1) is provided in the upper middle part of the inner wall of the alkaline washing container (5). A plurality of second spray pipes (5-4) are provided below the second gas-liquid separation membrane (5-1). A main valve is provided at the front end of the alkaline washing container (5), and the second spray pipe (5-4) is connected to the external alkaline solution. A second packing layer (5-5) is provided in the middle of the inner wall of the alkaline washing container (5), and the second packing layer (5-5) is located below the second spray pipe (5-4). The bottom (5-6) of the alkaline washing container (5) is a drain outlet with a conical structure. The first air outlet pipe (4-3) of the acid washing container (4) is connected to the second air inlet pipe (5-2) at the top of the alkaline washing container (5). The dehydration container (6) has a third air inlet pipe (6-2) at the top center and a waste gas outlet pipe (6-3) at the top. A silicone layer (6-1) is provided in the middle of the inner wall of the dehydration container (6). The bottom of the dehydration container (6) has a hot air inlet (6-4) and a purified biogas outlet (6-5). A temperature sensor is provided on the hot air inlet (6-4) and a humidity sensor is provided on the purified biogas outlet (6-5). The second air outlet pipe (5-3) of the alkaline washing container (5) is connected to the third air inlet pipe (6-2) at the top of the dehydration container (6). The gas mixing tank (7) is uniformly arranged with multiple vertically arranged baffles (7-1). The air inlet and air outlet are located at the two ends of the gas mixing tank (7), and an oxygen inlet pipe (7-2) is provided at the end near the air inlet. The purified biogas outlet (6-5) of the dehydration container (6) is connected to the air inlet of the gas mixing tank (7). The air outlet of the gas mixing tank (7) is connected to the nano-aeration head (9) at the bottom of the anaerobic digester (1) through the circulation pump (8). The system is also equipped with a controller. The signal input terminal of the controller is connected to the signal output terminals of all temperature sensors, pH probes, gas analyzers and humidity sensors. The signal output terminal of the controller is connected to the signal input terminal of the main valve at the front end of the stirring device (1-1), vacuum pump (2), circulation pump (8), first spray pipe (4-4) and second spray pipe (5-4).

2. The system for alleviating ammonia inhibition of anaerobic digestion of medium-high temperature kitchen waste by coupling negative pressure and biogas backflow according to claim 1, characterized in that The pore size of the nano-aeration head (9) is 50nm to 100nm.

3. The system for alleviating ammonia inhibition of anaerobic digestion of medium-high temperature kitchen waste by coupling negative pressure and biogas backflow according to claim 1, characterized in that The pore size of the first gas-liquid separation membrane (4-1) is 0.1 μm to 0.5 μm.

4. The system for alleviating ammonia inhibition of anaerobic digestion of medium-high temperature kitchen waste by coupling negative pressure and biogas backflow according to claim 1, characterized in that The second gas-liquid separation membrane (5-1) has a pore size of 0.1 μm to 0.5 μm.

5. The system for mitigating ammonia inhibition of anaerobic digestion of medium-high temperature kitchen waste by coupling negative pressure and biogas backflow according to claim 1, characterized in that The vacuum pump (2) is a dry screw vacuum pump.

6. The system for mitigating ammonia inhibition of anaerobic digestion of medium-high temperature kitchen waste by coupling negative pressure and biogas backflow according to claim 1, characterized in that The filling height standard of the first filler layer (4-5) and the second filler layer (5-5) is: H f / D≥0.8, wherein H f is the filling height, and D is the diameter of the filler column, and the units are the same.

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