CN109226188B - Method for treating kitchen waste by hydrothermal carbonization coupled anaerobic digestion - Google Patents
Method for treating kitchen waste by hydrothermal carbonization coupled anaerobic digestion Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
- B09B3/40—Destroying solid waste or transforming solid waste into something useful or harmless involving thermal treatment, e.g. evaporation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B5/00—Operations not covered by a single other subclass or by a single other group in this subclass
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- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
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- Treatment Of Sludge (AREA)
Abstract
The invention provides a method for treating kitchen waste by hydrothermal carbonization coupled anaerobic digestion, which comprises the following steps: (1) carrying out hydrothermal carbonization reaction on the crushed kitchen waste, separating a hydrothermal carbonization reaction product to obtain hydrothermal liquid and a solid-phase product, and drying the solid-phase product to obtain hydrothermal carbon; (2) and (2) carrying out anaerobic digestion treatment on the hydrothermal carbon, the hydrothermal liquid or the mixture of the hydrothermal carbon and the hydrothermal liquid obtained in the step (1). The method for treating the kitchen waste by coupling the hydrothermal carbonization with the anaerobic digestion provided by the invention can realize the recycling, harmless treatment and reduction of the kitchen waste by coupling the hydrothermal carbonization technology and the anaerobic digestion technology to treat the kitchen waste.
Description
Technical Field
The invention relates to a method for treating kitchen waste by hydrothermal carbonization coupled anaerobic digestion, and belongs to the technical field of waste organic matter recycling and clean energy production application.
Background
The kitchen waste is food residue in canteens, families and catering industry, mainly comprises various substances such as steamed buns, rice, peels, vegetables, oil water and the like, mainly comprises starch, protein, inorganic salt, lipid, cellulose and the like in chemical composition, and has the characteristics of high water content and high organic matter, salt content and oil content. With the increase of economy, the restaurant and kitchen waste rapidly increases while the catering industry rapidly develops, according to statistics, the national kitchen waste production amount reaches 9972 ten thousand tons in 2017, the countries begin large-scale trial construction work of kitchen waste treatment facilities in the early period, the aim of 3 ten thousand tons/day is planned to be achieved at the end of 2015, but the actual treatment capacity is only 1.49 ten thousand tons/day. The total market space of the whole kitchen waste can reach 1000-1500 billion yuan in the coming years.
Improper treatment of kitchen waste can have a great influence on social life, and is a great hidden danger of food safety. The kitchen waste contains a large amount of organic matters and oil-fat available components, so that if the kitchen waste can be effectively utilized, resources can be saved, a larger economic value can be generated, meanwhile, the recycling, harmlessness and reduction of the waste can be realized, and the urban modern construction is facilitated. At present, the main modes for treating the kitchen waste in China are incineration, landfill and composting, and the three treatment modes have low efficiency and pollute the environment to a certain extent. The anaerobic digestion technology utilizes microorganisms to decompose complex organic matter macromolecules into complex organic matter micromolecules and inorganic matters and generate biogas, the generated biogas can be used for power generation and energy supply, the mode is a good mode for treating the kitchen waste, but the organic load of the kitchen waste treated by the anaerobic digestion technology is high, and a large amount of biogas residues and biogas slurry which are difficult to treat can be generated. The hydrothermal carbonization technology is that in a closed reaction container, an aqueous solution is used as a reaction medium, and substances are directly converted into gaseous, liquid and solid products under the heating condition, so that the substances which are difficult to dissolve or insoluble in the normal condition are dissolved and recrystallized.
Chinese patent CN107142296A discloses a method for producing ethanol by utilizing kitchen waste, which is to perform hydrothermal pretreatment on sorted kitchen waste and then utilize microorganisms to ferment the separated solid kitchen waste to prepare ethanol. The invention uses the solid component for producing ethanol, but the solid can be hydrolyzed to generate a large amount of organic acid in the pretreatment process, and the invention ignores the utilization of the liquid phase, and leads to a part of energy loss. Chinese patent CN105414158A discloses a method for treating oil by coupling anaerobic digestion and hydrothermal liquefaction of kitchen waste, which is to carry out hydrothermal liquefaction on oil to prepare liquid-phase fuel and directly carry out anaerobic digestion on a solid phase. The invention directly carries out anaerobic digestion on the solid phase, can cause anaerobic environment acidification caused under high load, influences treatment efficiency, and generates a large amount of biogas residues and biogas slurry which are difficult to treat.
Therefore, the method for treating the kitchen waste by hydrothermal carbonization coupled anaerobic digestion is an urgent technical problem in the field.
Disclosure of Invention
In order to solve the defects and shortcomings, the invention aims to provide a method for treating kitchen waste by hydrothermal carbonization coupled anaerobic digestion.
The invention also aims to provide the hydrothermal carbon.
In order to achieve the above objects, in one aspect, the present invention provides a method for treating kitchen waste by hydrothermal carbonization coupled anaerobic digestion, wherein the method comprises the following steps:
(1) carrying out hydrothermal carbonization reaction on the crushed kitchen waste, separating a hydrothermal carbonization reaction product to obtain hydrothermal liquid and a solid-phase product, and drying the solid-phase product to obtain hydrothermal carbon;
(2) and (2) carrying out anaerobic digestion treatment on the hydrothermal carbon, the hydrothermal liquid or the mixture of the hydrothermal carbon and the hydrothermal liquid obtained in the step (1).
According to a particular embodiment of the invention, in said method, step (1) comprises in particular the steps of:
mixing the crushed kitchen waste with deionized water, and placing the obtained mixture in a reactor liner for hydrothermal carbonization reaction;
and after the reaction is finished, introducing circulating water to cool to room temperature, separating to obtain hydrothermal liquid and a solid-phase product, and then sending the solid-phase product to an oven to be dried to obtain hydrothermal carbon.
According to the specific embodiment of the invention, the temperature and the drying time of the drying in the step (1) of the method are not specifically required, and the temperature and the drying time can be reasonably set by a person skilled in the art according to the field operation requirement, so long as the aim of drying the solid-phase product to obtain the hydrothermal carbon can be fulfilled.
According to a particular embodiment of the invention, in the process, the yield of the hydrothermal char is from 42.33 to 49.33%, the calorific value is from 28.36 to 31.11MJ/kg, the O/C atomic ratio is from 0.15 to 0.24, and the H/C atomic ratio is from 1.10 to 1.30.
According to the specific embodiment of the invention, in the step (1), the temperature of the hydrothermal carbonization reaction is 180-260 ℃, and the reaction time is 2-4 h;
preferably, the temperature of the hydrothermal carbonization reaction is 180 ℃, and the reaction time is 2 h.
According to a specific embodiment of the present invention, in the step (2) of the method, the temperature of anaerobic digestion is 37. + -. 1 ℃, the anaerobic digestion time is 45 days, and pH is not adjusted.
According to a particular embodiment of the invention, the method further comprises, before the anaerobic digestion treatment, continuously feeding nitrogen into the system to ensure that the system maintains operation in an anaerobic environment;
preferably, the time for introducing the nitrogen is 1-3 min.
According to a specific embodiment of the present invention, in the method, the hydrothermal solution is added in an amount of 50 to 200mL/L based on the total volume of the inoculum solution used for the anaerobic digestion treatment.
According to a specific embodiment of the invention, in the method, the addition amount of the hydrothermal carbon is 5-15g/L based on the total volume of the inoculation liquid used for anaerobic digestion treatment;
preferably, the adding amount of the hydrothermal carbon is 10 g/L.
According to the specific embodiment of the invention, the inoculation liquid used for anaerobic digestion treatment in the method is not particularly required, and a person skilled in the art can select a proper inoculation liquid according to the field operation needs as long as the purpose of anaerobic digestion treatment in the invention can be realized. For example, the inoculation liquid used in the method can be biogas slurry, and the biogas slurry comprises biogas slurry obtained after fermentation of activated sludge, crop straws, cultivation excrement, kitchen waste and the like; in the specific embodiment of the invention, the inoculation liquid is biogas slurry taken from Ashbya landfill (Changpian area in Beijing city).
According to a specific embodiment of the invention, the method further comprises the operation of recycling the hydrothermal solution obtained in the step (1) as a solvent for the hydrothermal carbonization reaction;
preferably, the number of cycles is 5 to 7.
The hydrothermal liquid obtained after the hydrothermal carbonization reaction is recycled, so that the yield and the calorific value of the hydrothermal carbon can be improved.
According to a specific embodiment of the invention, in the method, the kitchen waste comprises one or more of meat, vegetables, rice, steamed bread, noodles, fruits and oily water.
According to the specific embodiment of the invention, in the method, the water content of the kitchen waste is 70-90%; preferably 80%.
According to a specific embodiment of the invention, the method further comprises the operation of biomass conditioning on the hydrothermal carbon to prepare the biofuel. The biomass conditioning is a conventional technical means in the field, and a person skilled in the art can select a proper biomass conditioning process according to operation needs as long as the purpose of preparing the biofuel according to the invention can be realized.
According to a specific embodiment of the present invention, the method further comprises an operation of pretreating the kitchen waste, wherein the pretreatment method is a conventional method in the field, and as in the specific embodiment of the present invention, the pretreatment method comprises the following specific steps:
after the kitchen waste is collected and transported, firstly, rough separation is carried out, and substances which can not be subjected to hydrothermal carbonization reaction, such as glass, metal, stone and the like, are separated; then, centrifugal deoiling is carried out, an oil phase and a solid phase are separated, the oil phase is sent to be processed into the biodiesel, and the solid phase enters a next crushing system for crushing; after the crushing is finished, the mixture enters a preheating tank for stirring and preheating, and the preheating temperature is 80-90 ℃. The kitchen waste after being crushed is preheated at the temperature of 80-90 ℃ so as to be subjected to preliminary hydrolysis, and the problem of uneven reaction caused by direct reaction of the kitchen waste in a hydrothermal reaction tank is solved.
According to a specific embodiment of the present invention, in the hydrothermal carbonization reaction, in a closed reaction vessel, subcritical water exhibits both acidic and basic properties under heating conditions, and the resultant is used as both a solvent and a catalyst to increase the solubility of organic substances in water, thereby hydrolyzing substances which are usually insoluble or insoluble to form small molecular substances, and then the small molecular substances are recrystallized to form a new polymer under the catalytic action of the subcritical water. The hydrothermal carbonization product exhibits different properties for different feedstocks. For kitchen waste, the kitchen waste is rich in a large amount of organic matters, and undergoes dehydration, decarbonation and polymerization in the hydrothermal carbonization process, so that the C content of a solid-phase product is obviously improved, and meanwhile, the solid-phase product has higher calorific value and can be used as a biofuel, an additive for anaerobic digestion reaction and a carbon base to be combined with a fertilizer to prepare a slow release agent. The liquid phase (hydrothermal liquid) is rich in a large amount of small molecular organic acids, the organic acids mainly comprise acetic acid, are fermentation substrates of methanogens in the anaerobic digestion process, and can be used in the anaerobic digestion process; the hydrothermal solution may be recycled as a solvent required for the hydrothermal carbonization reaction.
The anaerobic digestion process is generally divided into three stages, namely an organic matter hydrolysis stage, an acid and hydrogen production stage and a methane production stage. Based on the current research, the biochar is added into an anaerobic digestion system, so that the direct electron transfer capacity among microbial species can be improved, and further, the methane production in the anaerobic digestion process is improved. The method provided by the invention is characterized in that hydrothermal carbon obtained after hydrothermal carbonization of the kitchen waste is added into an anaerobic digestion system, hydrolysis bacteria and methanogen in the anaerobic digestion system are adsorbed on the surface of the hydrothermal carbon through biochemical adsorption by the added hydrothermal carbon, so that the hydrolysis efficiency of the hydrolysis bacteria is improved, the synergistic effect among microorganisms is enhanced, meanwhile, the hydrothermal carbon can also be used as a fermentation raw material, the organic acid content in the system is improved, and the methane yield is further improved.
In addition, the raw material for preparing the hydrothermal carbon provided by the invention is kitchen waste, the prepared hydrothermal carbon is an environment-friendly substance, the preparation cost is low, and the application effect is obvious; in the specific embodiment of the invention, the hydrothermal carbon, the hydrothermal liquid and the mixture of the hydrothermal carbon and the hydrothermal liquid are respectively added into an anaerobic digestion biogas system taking organic garbage biogas slurry as an inoculum, and experimental results show that after the hydrothermal carbon is added, the accumulated methane yield and the methane production rate are both improved to a significant extent.
Therefore, the method for treating the kitchen waste by coupling the hydrothermal carbonization with the anaerobic digestion provided by the invention can realize the recycling, harmless treatment and reduction of the kitchen waste by coupling the hydrothermal carbonization technology and the anaerobic digestion technology to treat the kitchen waste.
Specifically, in the most preferred embodiment of the invention, the temperature of the hydrothermal carbonization reaction is 180 ℃, the reaction time is 2H, and the water content of the kitchen waste raw material is 80%, so that the prepared hydrothermal carbon and the hydrothermal solution have optimal performance, wherein the calorific value of the hydrothermal carbon is 29.50MJ/kg, the O/C atomic ratio is 0.24, and the H/C atomic ratio is 1.30; the total amount of small molecular organic acid in the hydrothermal solution is 2103mg/L, wherein the content of acetic acid is 1499 mg/L. Therefore, the combustion property of the hydrothermal carbon obtained by treating the kitchen waste by using the hydrothermal carbonization technology is superior to that of lignite, and the hydrothermal liquid is rich in organic acid and can be used for anaerobic digestion.
On the other hand, the invention also provides hydrothermal carbon, which is obtained by performing hydrothermal carbonization reaction on the crushed kitchen waste for 2-4h at the temperature of 180-260 ℃, then separating the hydrothermal carbonization reaction product to obtain hydrothermal liquid and a solid-phase product, and drying the solid-phase product.
According to the specific embodiment of the invention, the hydrothermal carbon is obtained by performing hydrothermal carbonization reaction on crushed kitchen waste for 2 hours at 180 ℃, then separating a hydrothermal carbonization reaction product to obtain a hydrothermal solution and a solid-phase product, and drying the solid-phase product.
According to a particular embodiment of the invention, the hydrothermal charcoal has a yield of 42.33 to 49.33%, a calorific value of 28.36 to 31.11MJ/kg, an O/C atomic ratio of 0.15 to 0.24 and an H/C atomic ratio of 1.10 to 1.30.
Drawings
FIG. 1 is a graph showing the effect of hydrothermal cycle number on hydrothermal carbon yield and calorific value in example 2 of the present invention;
FIG. 2 is a graph showing the relationship between the cumulative methane production of the experimental group A, the experimental group B and the experimental group C according to the variation of the fermentation time in example 3 of the present invention;
FIG. 3 is a graph showing the relationship between the methane production rates of the experimental group A, the experimental group B and the experimental group C according to the change of the fermentation time in example 3 of the present invention;
fig. 4 is a schematic structural diagram of a system used in the method for treating kitchen waste by hydrothermal carbonization-coupled anaerobic digestion provided in embodiment 1 of the present invention.
The main reference numerals in fig. 4 illustrate:
1. deoiling;
2. a pulverizing system;
3. a preheating tank;
4. a hydrothermal reaction tank;
5. a steam generator;
6. an outer buffer tank;
7. a vapor recovery tank;
8. a filtration system;
9. an anaerobic reactor;
10. washing the tower with water;
11. and (7) a dryer.
Detailed Description
In order to clearly understand the technical features, objects and advantages of the present invention, the following detailed description of the technical solutions of the present invention will be made with reference to the following specific examples, which should not be construed as limiting the implementable scope of the present invention.
Example 1
The embodiment provides a method for treating kitchen waste by hydrothermal carbonization coupled anaerobic digestion, wherein the method is realized by adopting a treatment system as shown in fig. 4, and the method comprises the following specific steps:
(1) pretreatment of kitchen waste
After the kitchen waste is collected and transported, firstly, rough separation is carried out, and substances which can not be subjected to hydrothermal carbonization reaction, such as glass, metal, stone and the like, are separated; then, centrifugal deoiling is carried out in the deoiling tank 1, an oil phase and a solid phase are separated, the oil phase is sent to process biodiesel, and the solid phase enters the next crushing system 2 for crushing; after the crushing is finished, the crushed materials enter a preheating tank 3 for stirring and preheating, and the preheating temperature is 80-90 ℃.
(2) Hydrothermal carbonization of kitchen waste
The preheated kitchen waste is sent to a hydrothermal reaction tank 4 for hydrothermal carbonization reaction, the temperature of the hydrothermal carbonization reaction is 180-260 ℃, steam is used for heating in the reaction process, the steam can be provided by a steam generator 5, or high-temperature steam from a refinery boiler, and the rotating speed is set to be 150rpm in the reaction process. After the reaction is completed, the mixture is sent to an external buffer tank 6 for cooling, and steam is recovered by a steam recovery tank 7 and sent to a preheating tank 3 for preheating the raw materials. The mixture is separated by a filtration system 8.
(3) Anaerobic digestion of products
One part of the separated hydrothermal solution is used for mixing and size mixing with the kitchen waste, and the other part is sent to an anaerobic reactor 9; a part of the hydrothermal carbon is sent to a water washing tower 10 for water washing, the rest is sent to an anaerobic reactor 9 for co-digestion with the hydrothermal liquid, the generated biogas can be used for power generation, and the waste heat in the power generation process can be recycled, for example, the temperature of the anaerobic reactor can be maintained.
(4) Hydrothermal carbon quenching and tempering forming fuel
The hydrothermal carbon washed by the water washing tower is dried by a dryer 11, screened to remove large granular substances which are not carbonized by the hydrothermal process, and then subjected to biomass conditioning and co-molding to prepare the biofuel.
Therefore, the method for treating the kitchen waste by hydrothermal carbonization coupled anaerobic digestion has high treatment efficiency, and can realize the recycling, harmless and reduction treatment of the kitchen waste.
Example 2
The embodiment provides a method for recycling a liquid phase obtained after hydrothermal carbonization of kitchen waste to improve solid phase yield and calorific value, which comprises the following steps:
(1) after the kitchen waste is collected and transported, firstly, rough separation is carried out, and substances which can not be subjected to hydrothermal carbonization reaction, such as glass, metal, stone and the like, are separated; then, centrifugal deoiling is carried out, an oil phase and a solid phase are separated, the oil phase is sent to be processed into the biodiesel, and the solid phase enters a next crushing system for crushing; after the crushing is finished, the mixture enters a preheating tank for stirring and preheating, and the preheating temperature is 80-90 ℃.
Wherein, the kitchen waste in the step (1) comprises meat, rice, steamed bread, fruits and vegetables and the like.
(2) Mixing 50g of the kitchen waste (with the water content of 80%) obtained in the step (1) with 25mL of deionized water, placing the mixture in an inner container of a high-temperature and high-pressure hydrothermal reactor, setting the rotating speed of a stirrer to be 100rpm in the reaction process at 180 ℃, maintaining the rotating speed for 2 hours, and introducing circulating water to cool the reactor to room temperature. And separating the reacted mixture to obtain a solid phase and hydrothermal liquid, and sending the solid phase to an oven to be cooled for 24 hours to obtain hydrothermal carbon.
The calorific value of the hydrothermal carbon obtained in the embodiment is 29.50MJ/kg, the O/C atomic ratio is 0.24, and the H/C atomic ratio is 1.30; the total amount of small molecular organic acid in the hydrothermal solution is 2103mg/L, wherein the content of acetic acid is 1499 mg/L;
(3) and (3) sending the liquid phase obtained after the hydrothermal carbonization reaction in the step (2) to the next batch of experiments for recycling, wherein the circulation time is 6 times.
According to detection, after the hydrothermal solution prepared in the embodiment is subjected to the first 3 cycles, the solid-phase yield of the hydrothermal carbonization reaction is increased from 40% to 43.39%, 46.13% and 46.97% respectively; respectively increased by 3.39%, 6.13% and 6.97%; from cycle 4, the solid phase yield remained essentially unchanged; in addition, the hydrothermal solution prepared in the embodiment is recycled, and the calorific value of the obtained hydrothermal carbon is also improved to a certain extent.
Wherein, the graph of the influence of the cycle number of the hydrothermal solution on the yield and the calorific value (HHV) of the hydrothermal carbon is shown in figure 1, and as can be seen from figure 1, the hydrothermal solution can be used as the solvent for the hydrothermal carbonization reaction for recycling to improve the yield and the calorific value of the hydrothermal carbon, the specific reason is that: the hydrothermal solution is used as a solvent for hydrothermal carbonization reaction for cyclic utilization, so that the organic small molecular acid in the hydrothermal solution can be subjected to condensation polymerization, secondary polymerization and other reactions again in the cyclic hydrothermal process, and the yield and the heat value of the obtained hydrothermal carbon can be improved.
Example 3
The embodiment provides a method for fermenting hydrothermal carbon, hydrothermal liquid and a mixture of the hydrothermal carbon and the hydrothermal liquid obtained after hydrothermal carbonization reaction to improve gas production, which comprises the following steps:
(1) experimental group a: the fermentation raw material was the hydrothermal charcoal prepared in example 1, the fermentation concentration was 10g/L (calculated on the total volume of the inoculation liquid used), the total reaction volume was 250mL, and the inoculation liquid was biogas slurry from a landfill, such as from asu landfill (chang plain area, beijing), without any accelerator added.
(2) Experimental group B: the fermentation raw material is hydrothermal liquid prepared in example 1, the fermentation volume is 100mL/L (calculated by the total volume of the inoculation liquid used), the total reaction volume is 250mL, and the inoculation liquid is biogas slurry of a refuse dump, such as biogas slurry taken from Ashbya landfill (Changpian district, Beijing city), and no accelerator is added.
(3) Experimental group C: the fermentation raw material is the mixture of hydrothermal solution and hydrothermal charcoal prepared in example 1, the fermentation volume of the hydrothermal solution is 100mL/L, the fermentation concentration of the hydrothermal charcoal is 10g/L, the total reaction volume is 250mL, the inoculation liquid is biogas slurry of a refuse dump, such as biogas slurry taken from Ashbya landfill (Changpio district, Beijing city), and no accelerator is added.
In the experimental groups A-C, the fermentation temperature is 37 +/-1 ℃, the anaerobic digestion time is 45 days, and the pH is not adjusted.
Through detection, in the experimental group A of the embodiment, the accumulated methane production amount is 360mL, and the maximum methane production rate is 26.9 mL/d; in the experimental group B, the accumulated methane production amount is 69mL, and the maximum methane production rate is 5.3 mL/d; in test group C, the cumulative methane production was 538.8mL, and the maximum methane production rate was 56.8 mL/d.
Wherein, the curve chart of the relationship between the accumulated methane production and the fermentation time of the experimental group A, the experimental group B and the experimental group C is shown in FIG. 2; the relationship curve diagrams of the methane production rate and the fermentation time of the experimental group A, the experimental group B and the experimental group C are shown in fig. 3, and as can be seen from fig. 2 to fig. 3, the accumulated methane production amount and the methane production rate of the system can be improved to a greater extent by adding the hydrothermal carbon obtained after the hydrothermal carbonization treatment of the kitchen waste into the anaerobic system.
Claims (9)
1. A method for treating kitchen waste by hydrothermal carbonization coupled anaerobic digestion is characterized by comprising the following steps:
(1) carrying out hydrothermal carbonization reaction on the crushed kitchen waste, separating a hydrothermal carbonization reaction product to obtain hydrothermal liquid and a solid-phase product, and drying the solid-phase product to obtain hydrothermal carbon; the yield of the hydrothermal carbon is 42.33-49.33%, the heat value is 28.36-31.11MJ/kg, the atomic ratio of O/C is 0.15-0.24, and the atomic ratio of H/C is 1.10-1.30;
the step (1) further comprises the following steps:
mixing the crushed kitchen waste with deionized water, and placing the obtained mixture in a liner of a high-temperature high-pressure hydrothermal reactor for hydrothermal carbonization reaction;
after the reaction is finished, circulating water is introduced to cool to room temperature, hydrothermal liquid and solid-phase products are obtained through separation, and then the solid-phase products are sent to an oven to be dried to obtain hydrothermal carbon;
(2) carrying out anaerobic digestion treatment on the hydrothermal carbon, the hydrothermal liquid or the mixture of the hydrothermal carbon and the hydrothermal liquid obtained in the step (1);
the adding amount of the hydrothermal solution is 50-200mL/L based on the total volume of inoculation liquid used for anaerobic digestion treatment;
the adding amount of the hydrothermal carbon is 5-15g/L based on the total volume of inoculation liquid used for anaerobic digestion treatment;
in the step (2), the temperature of anaerobic digestion is 37 +/-1 ℃, the anaerobic digestion time is 45 days, and the pH value is not adjusted;
the method also comprises the operation of recycling hydrothermal liquid obtained in the step (1) as a solvent used for the hydrothermal carbonization reaction; the cycle number is 5-7.
2. The method as claimed in claim 1, wherein the temperature of the hydrothermal carbonization reaction in step (1) is 180-260 ℃ and the reaction time is 2-4 h.
3. The method according to claim 2, wherein the temperature of the hydrothermal carbonization reaction is 180 ℃ and the reaction time is 2 h.
4. The method of claim 1, further comprising continuing to introduce nitrogen into the system prior to anaerobic digestion to ensure that the system is maintained in an anaerobic environment.
5. The method according to claim 4, wherein the nitrogen is introduced for 1-3 min.
6. The method according to claim 1, wherein the amount of the hydrothermal charcoal added is 10 g/L.
7. The method according to claim 1, wherein the kitchen waste comprises one or more of meat, vegetables, rice, steamed bread, noodles, fruits and oily water.
8. The method according to claim 7, wherein the water content of the kitchen waste is 70-90%.
9. The method according to claim 8, wherein the water content of the kitchen waste is 80%.
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