CN114752632A - Application method of modified biochar in methane production by anaerobic digestion of kitchen waste - Google Patents
Application method of modified biochar in methane production by anaerobic digestion of kitchen waste Download PDFInfo
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 90
- 239000010806 kitchen waste Substances 0.000 title claims abstract description 67
- 230000029087 digestion Effects 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims abstract description 45
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 27
- UGKDIUIOSMUOAW-UHFFFAOYSA-N iron nickel Chemical compound [Fe].[Ni] UGKDIUIOSMUOAW-UHFFFAOYSA-N 0.000 claims abstract description 20
- 239000002131 composite material Substances 0.000 claims abstract description 11
- 238000002360 preparation method Methods 0.000 claims abstract description 11
- 229910003264 NiFe2O4 Inorganic materials 0.000 claims abstract description 8
- 239000002245 particle Substances 0.000 claims abstract description 8
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 27
- 238000003756 stirring Methods 0.000 claims description 26
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- 238000001035 drying Methods 0.000 claims description 23
- 239000000843 powder Substances 0.000 claims description 21
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 4
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- 239000000126 substance Substances 0.000 claims description 4
- 238000003763 carbonization Methods 0.000 claims description 2
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- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 21
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- 230000000052 comparative effect Effects 0.000 description 11
- 239000007789 gas Substances 0.000 description 11
- VZSRBBMJRBPUNF-UHFFFAOYSA-N 2-(2,3-dihydro-1H-inden-2-ylamino)-N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]pyrimidine-5-carboxamide Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)C(=O)NCCC(N1CC2=C(CC1)NN=N2)=O VZSRBBMJRBPUNF-UHFFFAOYSA-N 0.000 description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 8
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- 210000000988 bone and bone Anatomy 0.000 description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 3
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- 235000008331 Pinus X rigitaeda Nutrition 0.000 description 2
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- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000000696 methanogenic effect Effects 0.000 description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N nitrate group Chemical group [N+](=O)([O-])[O-] NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 2
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- 230000005764 inhibitory process Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- BLYYANNQIHKJMU-UHFFFAOYSA-N manganese(2+) nickel(2+) oxygen(2-) Chemical compound [O--].[O--].[Mn++].[Ni++] BLYYANNQIHKJMU-UHFFFAOYSA-N 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
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- C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
- C12P5/00—Preparation of hydrocarbons or halogenated hydrocarbons
- C12P5/02—Preparation of hydrocarbons or halogenated hydrocarbons acyclic
- C12P5/023—Methane
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Abstract
The invention belongs to the field of biochar preparation and the technical field of solid waste treatment, and particularly relates to an application method of modified biochar in methane production through anaerobic digestion of kitchen waste. Based on loading of iron-nickel composite oxide NiFe2O4The modified biochar particles are added into a kitchen waste anaerobic digestion methane production system and loaded with an iron-nickel composite oxide NiFe2O4The modified biochar optimizes the conductivity of the biochar, supplements metal trace elements required by anaerobic digestion, enriches anaerobic functional flora, strengthens the electron transfer process between acid-producing bacteria and methanogen, relieves the acidification problem of the system, and obviously improves the anaerobic digestion of the kitchen wasteThe methane yield is high, and the modified biochar has magnetism and is convenient to recycle. The invention also provides a preparation method of the modified biochar for the purposes, which is low in cost, simple in process and suitable for large-scale application of the modified biochar in the anaerobic digestion process of kitchen waste.
Description
Technical Field
The invention belongs to the field of biochar preparation and the technical field of solid waste treatment, and particularly relates to an application method of modified biochar in methane production through anaerobic digestion of kitchen waste.
Background
With the rapid development of economy, the yield of the kitchen waste is increased year by year, and proper treatment is urgently needed. The anaerobic digestion technology can effectively treat organic wastes and generate clean energy, and is an effective technical means for realizing the resource and energy treatment of the kitchen wastes at present. However, in the process of producing methane by anaerobic digestion of kitchen waste, a large amount of volatile fatty acid is accumulated due to rapid degradation of organic matters, so that the system is over-acidified, the methane yield is too low, and the like. At present, adding biochar into an anaerobic digestion system is proved to be one of important ways for improving the efficiency of generating methane by anaerobic digestion of kitchen waste. On the one hand, the biochar has rich pores, active functional groups and a larger specific surface area, and can provide a suitable growth microenvironment for microorganisms, and on the other hand, the biochar has good conductivity, so that the electron transfer process between syntrophic bacteria and methanogenic bacteria can be remarkably promoted, and the anaerobic digestion methanogenesis efficiency of kitchen waste is improved. In addition, the biochar is alkaline generally, so that the alkalinity of an anaerobic system of the kitchen waste can be improved, the problem of acid inhibition caused by quick hydrolysis and acidification of organic matters in the kitchen waste is effectively solved, and the stability of an anaerobic digestion process of the kitchen waste is improved. However, in the practical application process, in order to achieve a good dispersion effect, the particle size of the biochar is often so small that the biochar is difficult to recover, which not only causes the waste of the biochar, but also has certain pollution to the environment.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides an application method of modified biochar in methane production by anaerobic digestion of kitchen waste, which specifically comprises the following steps:
fully mixing the modified biochar with the kitchen waste, adding the mixed material into an anaerobic reactor, adjusting the initial pH of the solution in the anaerobic reactor to be neutral, and carrying out anaerobic digestion at a medium temperature to produce methane.
The kitchen waste can be pretreated before being mixed, and the pretreatment method comprises the following steps: removing parts of substances which are difficult to degrade biochemically, such as bones, fishbones, napkin paper and the like, in the kitchen waste through separation, and pulping the separated kitchen waste into pulp.
Preferably, the adding concentration of the modified biochar in the kitchen waste is 1-15g/L, and the method and conditions for producing methane by anaerobic digestion are as follows: adopting sequencing batch anaerobic digestion, adjusting pH of initial liquid in anaerobic reactor to 7.0-7.5 at 30-40 deg.C, adding water to dilute to solid content of 10-30%, and inoculating at inoculation rate (kg VS)Kitchen waste/kg VSInoculum) Is 1: (1-3) the organic load is 10-20gVS/L, wherein VS is the volatile solid content of the kitchen waste.
The modified charcoal is loaded with an iron-nickel composite oxide NiFe 2O4The biochar particles.
Further, after the methane production by anaerobic digestion is completed, the modified biochar can be recycled and reused, specifically as follows:
after the anaerobic digestion for producing methane is finished, separating biogas residues and biogas slurry, recovering modified biochar in the separated biogas residues by adopting magnetic separation, and cleaning and drying the recovered modified biochar for recycling. Wherein, the cleaning can be carried out by using alkali liquor such as NaOH and the like, and then repeatedly using deionized water for cleaning until the pH value is neutral.
Preferably, the magnetic separation method is to insert a magnet into the biogas residues to move back and forth so as to attract the modified biochar. The magnet can be N42 cylindrical strong magnet.
NiFe composite oxide of iron and nickel2O4Has good electrical conductivity, is loaded in the biochar and can further improve the biochar to microorganismsThe strengthening effect of direct electron transfer among biological species strengthens the electron transfer process between acid-producing bacteria and methanogenic bacteria, relieves the acidification problem of a system, enriches anaerobic functional flora, and realizes efficient and stable anaerobic digestion of the kitchen waste to produce methane. At the same time, because of the iron-nickel composite oxide NiFe2O4The magnetism of the biological carbon particles is ensured to be magnetic after the biological carbon particles are loaded, thereby being beneficial to loading the iron-nickel composite oxide NiFe 2O4The modified biochar is recycled.
The preparation of the modified biochar can adopt the following method:
mixing Ni2+Salt and Fe3+The salt is put into deionized water to be mixed and stirred evenly, then citric acid is added as a complexing agent to adjust the pH value to be neutral, and the stirring is carried out until sol is generated, specifically, the stirring can be carried out at the temperature of 80-100 ℃, the stirring time is 0.5-1.5h, and the rotating speed is 100 plus materials and 150 r/min. And then stopping stirring, drying the obtained sol, and pyrolyzing to obtain powder. Wherein Ni2+Salt and Fe3+The salt is preferably nitrate, and the ratio of the nitrate and the salt can be 1:2 theoretically, or can be adjusted appropriately on the basis, such as 1: (1.8-2.2). The added citric acid complexing agent needs to be able to achieve sufficient complexation of the metal ions.
Mixing the powder and the biochar, and putting the mixture into water, wherein the ratio of the powder to the biochar is 1: (5-10), carrying out solid-liquid separation after uniformly stirring, drying the separated solid, and then pyrolyzing to obtain the modified biochar.
The preparation method comprises the iron-nickel composite oxide NiFe2O4The powder and the biochar are directly mixed and pyrolyzed to prepare the modified biochar, the process is relatively simple, the cost is low, and the method is suitable for large-scale application of the modified biochar in the anaerobic digestion process of kitchen waste.
The preparation of the biochar can adopt the following method: the biomass waste is used as a raw material, dried, crushed and sieved to obtain biomass waste powder, and the biomass waste powder is subjected to pyrolysis carbonization, washed to neutrality and dried to obtain the biochar. The process of washing to neutrality can adopt a mode of washing the biochar by using acid solution such as HCl and the like and then repeatedly washing by using deionized water.
The biomass waste mainly comprises one or more of herbaceous biomass waste (corn straw, wheat straw, bamboo and the like), woody biomass waste (pine, oak, shrub and the like), kernel-shell biomass waste (coconut shell, peanut shell, hazelnut shell and the like) and the like. The biomass waste powder can be obtained by sieving the crushed biomass waste powder through a standard sieve with more than 100 meshes.
In all the above processes, the solid-liquid separation (for example, the solid-liquid separation of the biogas residue and the biogas slurry) can be performed simply by a solid-liquid separator. All drying temperatures are 80-105 ℃, the drying time is 24-48h, all pyrolysis is carried out in a tubular furnace and other equipment under the protection of nitrogen, the pyrolysis temperature is 400-.
Compared with the prior art, the invention has the following beneficial effects:
The invention is based on loading the iron-nickel composite oxide NiFe2O4The modified biochar is added into a kitchen waste anaerobic digestion methane production system, and an iron-nickel composite oxide NiFe is loaded2O4The modified biochar optimizes the conductivity of the biochar, supplements metal trace elements required by anaerobic digestion, enriches anaerobic functional flora, strengthens the electron transfer process between acid-producing bacteria and methanogen, relieves the acidification problem of the system, and obviously improves the methane yield of anaerobic digestion of the kitchen waste. The modified biochar has magnetism, is convenient to recycle, and can achieve a recovery rate of more than 50% through magnetic separation and recovery.
The invention also takes the biomass waste as the raw material, generates biochar after pyrolysis, and further prepares the nickel-iron composite oxide NiFe by adopting a sol-gel method2O4Then, the nickel manganese oxide NiFe is synthesized by high-temperature pyrolysis treatment2O4The biochar particles of (1). The cost is low, the process is simple, and the modified biochar is suitable for large-scale application in the anaerobic digestion process of the kitchen waste.
Drawings
FIG. 1 is a schematic diagram of the invention for preparing modified biochar to strengthen anaerobic digestion of kitchen waste to produce methane.
The specific implementation mode is as follows:
The details of the embodiment and effects of the present invention will be described below with reference to examples, in which materials and reagents are commercially available.
Example 1
A method for preparing modified biochar and applying the modified biochar to anaerobic digestion of kitchen waste for methane production is shown in figure 1 and comprises the following steps:
(1) the method comprises the following steps of taking coconut shells as raw materials, drying for 24 hours at 105 ℃, crushing, sieving, screening to 100 meshes, putting into a tubular furnace, carrying out slow pyrolysis at a heating rate of 10 ℃/min in a nitrogen atmosphere, carrying out pyrolysis for 1 hour at 500 ℃ to obtain biochar, cleaning the biochar with 1mol/L HCl solution, repeatedly cleaning with deionized water until the pH value is neutral, and then drying for 24 hours in an oven at 105 ℃;
(2) mixing Ni (NO)3)2.6H2O and Fe (NO)3)3.9H2Adding O into deionized water, mixing, and stirring, wherein Ni (NO)3)2.6H2O concentration of 0.1mol/L, Fe (NO)3)3.9H2O concentration is 0.2mol/L, citric acid is added as a complexing agent (the concentration of the added citric acid is 0.3mol/L), a small amount of ammonia water with the concentration of 2mol/L is added to adjust the pH value to be neutral, the mixture is placed into a magnetic stirrer, the magnetic stirring temperature is 90 ℃, the stirring time is 1h, the rotating speed is 120r/min, the stirring is stopped until sol is generated, the gel is dried in a drying oven at the temperature of 105 ℃ for 24h and then placed into a tube furnace, the gel is pyrolyzed at the temperature rising speed of 10 ℃/min in the nitrogen atmosphere for slow speed, and the nickel-iron composite oxide (NiFe) is obtained by pyrolyzing the temperature of 400 ℃ for 1h 2O4) Powder;
(3) weighing 10g of the biochar obtained in the step (1), putting the biochar and 1g of powder obtained in the step (2) into deionized water, uniformly stirring, drying at 105 ℃ for 24h, putting into a tubular furnace, and pyrolyzing at 400 ℃ for 1h to obtain the load nickel iron composite oxide NiFe2O4The modified biochar of (1).
(4) Sorting kitchen waste, removing bone, napkin, plastics, etc., crushing with a blender, making into slurry, mixing with water, stirring, and making into powderFully mixing the prepared modified biochar with kitchen waste, adding the mixture into an anaerobic reactor, wherein the adding amount of the modified biochar is 5g/L, adopting sequencing batch anaerobic digestion, adjusting the pH of an initial solution in the anaerobic reactor to 7.0 by using 5mol/L HCl solution or 3mol/L NaOH solution, the temperature is 37 ℃, adding water to dilute until the solid content is 10%, and the inoculation rate (kg VS/VS) isKitchen waste/kg VSInoculum) Is 1: 1, the organic load is 15gVS/L (VS is the volatile solid content of the kitchen waste).
(5) After the anaerobic digestion of the kitchen waste to produce methane is finished, firstly, carrying out simple solid-liquid separation on biogas residues and biogas slurry in a solid-liquid separator, then inserting an N42 cylindrical strong magnet into the biogas residues to move back and forth to collect modified biochar, finally, cleaning the collected modified biochar with 1mol/L NaOH, then cleaning with deionized water repeatedly until the pH value is neutral, drying at 105 ℃ for 24 hours, and recovering to obtain the modified biochar which can be recycled in an anaerobic digestion system.
The final methane gas yield was 373mL/g VS, which was 47% higher than that of comparative example 1-1 with no biochar added.
Comparative examples 1 to 1
The method is the same as example 1, except that:
the kitchen waste is directly subjected to anaerobic digestion without adding biochar;
the final methane gas production rate was 251mL/g VS.
Comparative examples 1 to 2
The method is the same as example 1, except that:
adding unmodified coconut shell biochar into the kitchen waste anaerobic digestion system, wherein the addition amount is 5.0 g/L;
the final methane gas production rate was 276mL/g VS, which was 10% higher than comparative example 1-1 without added biochar, but much lower than the gas production rate with the modified biochar added in example 1.
Example 2
The method is the same as example 1, except that:
adding NiFe loaded with nickel-iron composite oxide into anaerobic digestion system of kitchen waste2O4The addition amount of the modified coconut shell biochar is 1.0 g/L;
the final methane gas production rate was 313mL/g VS, which was 25% higher than comparative example 1-1 without added biochar.
Example 3
The method is the same as example 1, except that:
adding NiFe loaded with nickel-iron composite oxide into anaerobic digestion system of kitchen waste2O4The addition amount of the modified coconut shell biochar is 10 g/L;
the final methane gas production rate was 326mL/g VS, 30% higher than that of comparative example 1-1 without biochar addition.
Example 4
A preparation method of modified biochar comprises the following steps:
(1) taking corn straws as a raw material, drying for 24h at 105 ℃, crushing, sieving, screening to 100 meshes, putting into a tubular furnace, pyrolyzing at a low speed at a heating rate of 5 ℃/min in a nitrogen atmosphere, pyrolyzing for 1h at 600 ℃ to obtain biochar, cleaning the biochar with 1mol/L HCl solution, repeatedly cleaning with deionized water until the pH value is neutral, and then drying for 24h at 105 ℃ in an oven;
(2) mixing Ni (NO)3)2.6H2O and Fe (NO)3)3.9H2Adding O into deionized water, mixing, and stirring, wherein Ni (NO)3)2.6H2The concentration of the O solution is 0.1mol/L, Fe (NO)3)3.9H2The concentration of the O solution is 0.2mol/L, citric acid is added as a complexing agent (the concentration of the added citric acid is 0.3mol/L), a small amount of ammonia water with the concentration of 2mol/L is added to adjust the pH value to be neutral, the mixture is placed into a magnetic stirrer, the magnetic stirring temperature is 90 ℃, the stirring time is 1h, the rotating speed is 120r/min, the stirring is carried out until sol is generated, the stirring is stopped, the mixture is placed into a tube furnace after being dried in a drying oven at 105 ℃ for 24h, the pyrolysis is carried out at the slow speed of the heating rate of 5 ℃/min under the nitrogen atmosphere, and the pyrolysis is carried out at 400 ℃ for 1.5h to obtain the nickel-iron composite oxide (NiFe)2O4) Powder;
(3) weighing 10g of the biochar obtained in the step (1) and 1g of the powder obtained in the step (2) together, putting the mixture into deionized water, uniformly stirring, drying the mixture for 24 hours at 105 ℃, and putting the dried mixture into a tube furnace Pyrolyzing the mixture for 1 hour at 400 ℃ to obtain the nickel-iron-loaded composite oxide NiFe2O4And (3) modifying the biochar.
(4) Sorting the kitchen waste, removing bones, napkin, plastics and other substances, crushing until the particle size is less than or equal to 10mm, fully mixing the prepared modified biochar with the kitchen waste, adding the mixture into an anaerobic reactor, wherein the addition amount of the modified biochar is 5g/L, adopting sequencing batch anaerobic digestion, adjusting the pH of an initial solution in the anaerobic reactor to 7.0 by using 5mol/L HCl solution or 3mol/L NaOH solution, the temperature is 37 ℃, adding water to dilute until the solid content is 10%, and the inoculation rate (kg VS is 10%)Kitchen waste/kg VSInoculum) Is 1: 1, the organic load is 15gVS/L (VS is the volatile solid content of the kitchen waste).
(5) After the anaerobic digestion of the kitchen waste to produce methane is finished, firstly, carrying out simple solid-liquid separation on biogas residues and biogas slurry in a solid-liquid separator, then inserting an N42 cylindrical strong magnet into the biogas residues to move back and forth to collect modified biochar, finally, cleaning the collected modified biochar with 1mol/L NaOH, then cleaning with deionized water repeatedly until the pH value is neutral, drying at 105 ℃ for 24 hours, and recovering to obtain the modified biochar which can be recycled in an anaerobic digestion system.
The final methane gas production rate was 353mL/g VS, 41% higher than that of comparative example 1-1 without added biochar.
Comparative example 2 to 1
The method is the same as example 4, but the difference is that:
adding unmodified corn straw biochar into the kitchen waste anaerobic digestion system, wherein the addition amount is 5.0 g/L;
the final methane gas production rate was 269mL/g VS, which was 7% higher than comparative example 1-1 with no biochar added.
Example 5
The method is the same as example 4, but the difference is that:
adding NiFe loaded with nickel-iron composite oxide into anaerobic digestion system of kitchen waste2O4The addition amount of the modified corn straw biochar is 1.0 g/L;
the final methane gas production rate was 295mL/g VS, 18% higher than that of comparative example 1-1 without added biochar.
Example 6
The method is the same as the embodiment 4, and is different from the following steps:
adding NiFe loaded with nickel-iron composite oxide into anaerobic digestion system of kitchen waste2O4The addition amount of the modified corn straw biochar is 10 g/L;
the final methane gas production rate was 310mL/g VS, which was 24% higher than comparative example 1-1 without added biochar.
Example 7
A preparation method of modified biochar comprises the following steps:
(1) pine sawdust is used as a raw material, dried at 105 ℃ for 24 hours, crushed, sieved and 100-mesh screened, placed into a tubular furnace, pyrolyzed at a heating rate of 10 ℃/min in a nitrogen atmosphere at a low speed, pyrolyzed at 500 ℃ for 1 hour to obtain biochar, then the biochar is washed by 1mol/L HCl solution and then repeatedly washed by deionized water until the pH value is neutral, and then the biochar is placed in an oven at 105 ℃ for drying for 24 hours;
(2) Mixing Ni (NO)3)2.6H2O and Fe (NO)3)3.9H2Adding O into deionized water, mixing, and stirring, wherein Ni (NO)3)2.6H2The concentration of the O solution is 0.1mol/L, Fe (NO)3)3.9H2The concentration of the O solution is 0.2mol/L, citric acid is added as a complexing agent (the concentration of the added citric acid is 0.3mol/L), a small amount of ammonia water with the concentration of 2mol/L is added to adjust the pH value to be neutral, the mixture is placed into a magnetic stirrer, the magnetic stirring temperature is 80 ℃, the stirring time is 1.5h, the rotating speed is 150r/min, the stirring is carried out until sol is generated, the stirring is stopped, the mixture is placed into a tubular furnace after being dried in a drying oven at 105 ℃ for 24h, the pyrolysis is carried out at the heating rate of 10 ℃/min in the nitrogen atmosphere, and the pyrolysis is carried out for 1h at 400 ℃ to obtain the nickel-iron composite oxide (NiFe)2O4) Powder;
(3) weighing 10g of the biochar obtained in the step (1) and 2g of the powder obtained in the step (2), putting the biochar and the powder into deionized water, uniformly stirring, drying the biochar at 105 ℃ for 24 hours, putting the biochar into a tube furnace, and pyrolyzing the biochar at 400 ℃ for 1 hour to obtain the NiFe loaded nickel-iron composite oxide2O4The modified biochar of (1).
(4) Sorting kitchen waste to remove substances such as bones, napkin paper, plastics and the like, crushing and pulping by using a stirrer, fully mixing the prepared modified biochar with the kitchen waste, adding the mixture into an anaerobic reactor, wherein the addition amount of the modified biochar is 5g/L, adopting sequencing batch anaerobic digestion, adjusting the pH of an initial solution in the anaerobic reactor to 7.0 by using 5mol/L HCl solution or 3mol/L NaOH solution, the temperature is 30 ℃, adding water to dilute until the solid content is 10%, and the inoculation rate (kg VS is 10%) Kitchen waste/kg VSInoculum) Is 1: and 3, the organic load is 20gVS/L (VS is the volatile solid content of the kitchen waste).
(5) After the anaerobic digestion of the kitchen waste to produce methane is finished, firstly, carrying out simple solid-liquid separation on biogas residues and biogas slurry in a solid-liquid separator, then inserting an N42 cylindrical strong magnet into the biogas residues to move back and forth to collect modified biochar, finally, cleaning the collected modified biochar with 1mol/L NaOH, then cleaning with deionized water repeatedly until the pH value is neutral, drying at 105 ℃ for 24 hours, and recovering to obtain the modified biochar which can be recycled in an anaerobic digestion system.
The final methane gas production rate was 361mL/g VS.
The above is the preferred embodiment of the present invention, and it should be noted that: for those skilled in the art, without departing from the principle of the present invention, several adjustments and improvements may be made, such as material ratio, temperature, time, etc. of each step may be adjusted according to the numerical range in the summary of the invention, and these adjustments and improvements should be regarded as the protection scope of the present invention.
Claims (10)
1. An application method of modified biochar in methane production by anaerobic digestion of kitchen waste is characterized by comprising the following steps:
Fully mixing the modified biochar with the kitchen waste, feeding the mixed material into an anaerobic reactor, adjusting the initial pH of a solution in the anaerobic reactor to be neutral, and performing anaerobic digestion at a medium temperature to produce methane;
the modified charcoal is loaded with an iron-nickel composite oxide NiFe2O4The biochar particles.
2. The application method of the modified biochar in the anaerobic digestion of the kitchen waste to produce methane according to claim 1, characterized in that biogas residues and biogas slurry are separated after the anaerobic digestion to produce methane is finished, the modified biochar in the separated biogas residues is recovered by magnetic separation, and the recovered modified biochar is recycled after being cleaned and dried.
3. The application method of the modified biochar in the anaerobic digestion of kitchen waste for methane production according to claim 1 or 2, characterized in that the preparation method of the modified biochar comprises the following steps:
mixing Ni2+Salt and Fe3+Adding salt into deionized water, mixing, stirring, adding citric acid as complexing agent, adjusting pH to neutral, stirring until sol is generated, stopping stirring, drying the obtained sol, and pyrolyzing to obtain powder;
and mixing the powder and the biochar, putting the mixture into water, uniformly stirring, performing solid-liquid separation, drying the separated solid, and performing pyrolysis to obtain the modified biochar.
4. The application method of the modified biochar in methane production by anaerobic digestion of kitchen waste according to claim 3, characterized in that the preparation method of the biochar comprises: the biomass waste is used as a raw material, dried, crushed and sieved to obtain biomass waste powder, and the biomass waste powder is subjected to pyrolysis carbonization, washed to neutrality and dried to obtain the biochar.
5. The application method of the modified biochar in the anaerobic digestion of kitchen waste to produce methane according to claim 1 or 2, characterized in that the kitchen waste is pretreated and then mixed, the pretreatment is to remove substances which are difficult to biochemically degrade in the kitchen waste through separation, and the separated kitchen waste is pulped.
6. According toThe application method of the modified biochar in the anaerobic digestion and methane production of the kitchen waste, which is disclosed by claim 1 or 2, is characterized in that the adding concentration of the modified biochar in the kitchen waste is 1-15g/L, and the anaerobic digestion and methane production method and conditions are as follows: adopting sequencing batch anaerobic digestion, adjusting pH of initial liquid in anaerobic reactor to 7.0-7.5, adding water to dilute until solid content is 10% -30%, temperature is 30-40 deg.C, inoculation rate kg VS Kitchen waste/kg VSInoculumIs 1: (1-3) the organic load is 10-20 gVS/L.
7. The application method of the modified biochar in methane production by anaerobic digestion of kitchen waste as claimed in claim 4, wherein all drying temperatures are 80-105 ℃, drying time is 24-48h, all pyrolysis is pyrolysis under nitrogen protection, pyrolysis temperature is 400-.
8. The application method of the modified biochar in the anaerobic digestion of kitchen waste to produce methane according to claim 2, characterized in that the magnetic separation is that a magnet is inserted into biogas residues to move back and forth to attract the modified biochar.
9. The application method of the modified biochar in the anaerobic digestion and methane production of kitchen wastes as claimed in claim 3, characterized in that in the preparation process of the modified biochar, the stirring is carried out until sol is generated, the temperature is 80-100 ℃, the stirring time is 0.5-1.5h, and the rotation speed is 100-150 r/min.
10. The application method of the modified biochar in methane production through anaerobic digestion of kitchen waste according to claim 3, wherein in the mixing process of the powder and the biochar, the ratio of the powder to the biochar is 1: (5-10).
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