Method for preparing peanut shell biochar in carbon dioxide atmosphere to strengthen chicken manure anaerobic digestion

Abstract

The invention relates to a method for preparing peanut shell biochar in a carbon dioxide atmosphere to strengthen chicken manure anaerobic digestion, and belongs to the technical field of agricultural waste treatment. In order to solve the problem that the ammonia inhibition relieving effect of common charcoal in the anaerobic digestion process of chicken manure is limited, the invention provides a method for preparing peanut shell charcoal in a carbon dioxide atmosphere to strengthen anaerobic digestion of chicken manure. Dried and crushed peanut shells are placed in a carbon dioxide atmosphere, heated to a pyrolysis temperature at a certain heating rate, and cooled to room temperature after heat preservation for a certain time to obtain the peanut shell biochar, the porosity and the specific surface area of the biochar are remarkably improved, the porous structure of the peanut shell biochar is effectively optimized, the biochar is used for anaerobic digestion of chicken manure, and the yield of chicken manure is increased. Ammonia inhibition can be relieved through multiple mechanisms of promoting interspecific electron transfer, improving the microbial environment, enhancing the adsorption effect and the like, the recycling value of agricultural waste is increased, and a sustainable solution is provided for anaerobic digestion of high-nitrogen organic waste.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural waste treatment, and in particular relates to a method for preparing peanut shell biochar under a carbon dioxide atmosphere to enhance anaerobic digestion of chicken manure. Background Art

[0002] Chicken manure is a typical nitrogen-rich organic waste, and its anaerobic digestion (AD) process often faces the risk of inefficiency or even failure due to high ammonia nitrogen inhibition. Biochar, due to its excellent adsorption properties, buffering capacity, and microbial carrier function, has been shown to alleviate ammonia inhibition, promote methane production, and enhance the stability of AD systems. However, the pore structure and surface properties of conventional biochar have limited ability to fix free ammonia or ammonium ions. In a high ammonia nitrogen environment, peanut shell biochar prepared under a carbon dioxide atmosphere exhibits a more significant promoting effect in the AD system. This difference is attributed to the modified biochar's more optimized pore structure, enhanced electron transfer capacity, and more suitable microbial habitat.

[0003] Currently, the resource utilization of agricultural waste peanut shells is relatively limited. They are mainly used to make fuel pellets or as livestock bedding, and there is even direct incineration, which not only wastes resources but also exacerbates carbon emissions. It is worth noting that peanut shells are rich in cellulose and lignin. After pyrolysis, they can form biochar with rich pore structure and surface functional groups, which is expected to break the bottleneck of the existing application of biochar in chicken manure AD. At this stage, the use of agricultural waste peanut shells to develop high-performance biochar that can effectively solve the problem of ammonia inhibition in anaerobic digestion of chicken manure is an important technical problem that needs to be overcome in this field. Summary of the Invention

[0004] Aiming at the problem that ordinary biochar has limited effect in alleviating ammonia inhibition during anaerobic digestion of chicken manure, the present invention provides a method for preparing peanut shell biochar in a carbon dioxide atmosphere to enhance anaerobic digestion of chicken manure.

[0005] The technical solution of the present invention:

[0006] The method for preparing peanut shell biochar to enhance anaerobic digestion of chicken manure under carbon dioxide atmosphere comprises the following steps:

[0007] Step 1: Place the dried and crushed peanut shells in a carbon dioxide atmosphere, heat them to a pyrolysis temperature at a certain heating rate, keep them warm for a certain period of time, and then cool them to room temperature to obtain peanut shell biochar;

[0008] Step 2: Mix the chicken manure and inoculum as the anaerobic digestion substrate, add peanut shell biochar and mix well;

[0009] Step 3: Establish an anaerobic environment, seal it and run it under intermittent stirring conditions for 15 days until gas production stops, thus completing the anaerobic digestion of chicken manure.

[0010] Furthermore, the drying in step 1 is oven drying at 105° C., and the particle size of the peanut shell powder is 60 mesh.

[0011] Furthermore, the flow rate of the carbon dioxide gas is 400 mL / min.

[0012] Furthermore, the heating rate in step 1 is 5°C / min, and the pyrolysis temperature is 650-850°C.

[0013] Furthermore, the holding time of the pyrolysis temperature in step 1 is 2 hours.

[0014] Furthermore, the specific surface area of ​​the peanut shell biochar in step 1 is 180.12~409.61m 2 / g, and the mesopore volume is 0.09~0.20cm 3 / g.

[0015] Furthermore, the chicken manure in step 2 is mixed with the inoculum at a total solid content ratio of 1:1, and the inoculum is conventional cow dung biogas slurry.

[0016] Furthermore, the addition amount of the peanut shell biochar in step 2 is 15% (w / w) of the total solid content of the fermentation substrate.

[0017] Furthermore, the reaction temperature of the anaerobic environment in step 3 is 55±1°C.

[0018] Furthermore, the intermittent stirring condition in step 3 is 80 r / min, 5 min / time.

[0019] Beneficial effects of the present invention:

[0020] The peanut shell biochar prepared in the present invention under a carbon dioxide atmosphere has a distinct honeycomb structure. The carbon dioxide atmosphere promotes the decomposition of organic compounds and the formation of a porous structure. As the pyrolysis temperature increases, the internal structure of the biochar further decomposes, and a large amount of pyrolysis gas is released, resulting in an increase in surface cracks and a more developed porous structure. At high temperatures, carbon dioxide not only enhances the release of volatile matter but also acts as an activator to participate in the reorganization of the carbon skeleton, thereby significantly increasing the porosity and specific surface area of ​​the biochar, effectively optimizing the porous structure of the peanut shell biochar, and providing it with superior physical properties for applications in fields such as adsorption and catalysis.

[0021] The peanut shell biochar prepared by the present invention under a carbon dioxide atmosphere has a higher specific surface area, richer pore structure and significantly enhanced oxygen-containing functional group characteristics, which provide good attachment sites for microorganisms and enhance the electron transfer ability, thereby optimizing the metabolic activity of methanogens. The biochar prepared under a carbon dioxide atmosphere may further promote the anaerobic digestion process through its oxidizing properties. The peanut shell biochar prepared by the present invention has the combined effects of buffering pH, adsorbing inhibitory intermediates and continuously providing electron transfer pathways. It can not only increase methane production, but also prolong the stable methanogenesis period of the system, showing the best performance in promoting methanogenesis in anaerobic digestion of chicken manure.

[0022] This invention uses peanut shells to produce high-performance biochar for anaerobic digestion of chicken manure. This method alleviates ammonia inhibition through multiple mechanisms, including promoting interspecies electron transfer, improving the microbial environment, and enhancing adsorption. This strategy not only increases the resource value of agricultural waste but also provides a sustainable solution for the anaerobic digestion of high-nitrogen organic waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a scanning electron microscope image of peanut shell biochar N650 prepared in comparative example 1;

[0024] Figure 2 This is a scanning electron microscope image of peanut shell biochar C650 prepared in Example 1;

[0025] Figure 3 This is a scanning electron microscope image of peanut shell biochar N750 prepared in comparative example 2;

[0026] Figure 4 This is a scanning electron microscope image of peanut shell biochar C750 prepared in Example 2;

[0027] Figure 5 This is a scanning electron microscope image of peanut shell biochar N850 prepared in comparative example 3;

[0028] Figure 6 This is a scanning electron microscope image of peanut shell biochar C850 prepared in Example 3;

[0029] Figure 7 This is a comparison chart of the specific surface area and mesopore volume of peanut shell biochar prepared in Examples 1-3 and Comparative Examples 1-3;

[0030] Figure 8 FT-IR spectra of peanut shell biochar prepared in Examples 1-3 and Comparative Examples 1-3;

[0031] Figure 9 A comparison of daily methane production during anaerobic digestion of chicken manure using peanut shell bioaugmentation prepared in Examples 1-3 and Comparative Examples 1-3;

[0032] Figure 10 This is a comparison chart of the accumulated methane production during the anaerobic digestion of chicken manure bioaugmented with peanut shells prepared in Examples 1-3 and Comparative Examples 1-3. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below with reference to the embodiments, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be included in the scope of protection of the present invention. The process equipment or devices not specifically noted in the following examples are all conventional equipment or devices in the art. Unless otherwise specified, the raw materials used in the examples of the present invention can be obtained commercially; unless otherwise specified, the technical means used in the examples of the present invention are all conventional means well known to those skilled in the art.

[0034] Example 1

[0035] This embodiment provides a method for preparing peanut shell biochar for enhanced anaerobic digestion of chicken manure under a carbon dioxide atmosphere, which specifically includes the following steps:

[0036] Step 1: Dry the peanut shells in an oven at 105°C, crush them, and sieve them. Place the dried and crushed peanut shell powder with a particle size of 60 mesh in a porcelain boat. Heat it to a pyrolysis temperature of 650°C at a heating rate of 5°C / min in a carbon dioxide atmosphere. Keep it warm for 2 hours and then cool it to room temperature to obtain peanut shell biochar C650.

[0037] Step 2: Anaerobic digestion experiments were conducted using an automated methane potential test system (AMPTS II, Bioprocess Control AB, Sweden). The system consists of a constant-temperature water bath fermentation unit, a CO2 removal unit, and a methane metering device. Experiments were conducted in 500 mL glass reaction bottles with a working volume of 400 mL and a reaction temperature of 55 ± 1°C.

[0038] The chicken manure used in this example was obtained from a farm in Harbin, Heilongjiang, China. After removing large particles such as chicken feathers and stones, the chicken manure was thoroughly mixed to ensure homogeneity. It was stored in a -20°C refrigerator before anaerobic digestion. Cow dung was used as the inoculum raw material. The cow dung was obtained from Heilongjiang Boneng Green Energy Technology Group and anaerobically digested in a continuous reactor in the laboratory. The inoculum was collected in a laboratory-scale continuous anaerobic digestion reactor and degassed in an anaerobic environment at 35±1°C for 2 weeks to remove the influence of the biodegradable part. The main characteristics of the chicken manure and inoculum were determined according to the standard method (GB / T 28731-2012) and are shown in Table 1.

[0039] Table 1

[0040]

[0041] The experimental setup used chicken manure and inoculum mixed in a total solids ratio of 1:1 as the substrate, and peanut shell biochar was added at 15% (w / w) of the total solids content of the fermentation substrate and mixed evenly; no biochar was added to the control group.

[0042] Step 3: The reaction bottle was purged with high-purity nitrogen for 5 minutes to establish an anaerobic environment, and then sealed and operated under intermittent stirring conditions of 80 r / min and 5 min / time for 15 days until gas production stopped, completing the anaerobic digestion of chicken manure.

[0043] Example 2

[0044] This embodiment provides a method for preparing peanut shell biochar for enhanced anaerobic digestion of chicken manure under a carbon dioxide atmosphere. The only difference between this embodiment and Example 1 is that the pyrolysis temperature for preparing peanut shell biochar in step 1 of this embodiment is 750° C., and peanut shell biochar C750 is obtained.

[0045] Example 3

[0046] This embodiment provides a method for preparing peanut shell biochar for enhanced anaerobic digestion of chicken manure under a carbon dioxide atmosphere. The only difference between this embodiment and Example 1 is that the pyrolysis temperature for preparing peanut shell biochar in step 1 of this embodiment is 850° C., and peanut shell biochar C850 is obtained.

[0047] Comparative Example 1

[0048] This comparative example provides a method for preparing peanut shell biochar under a nitrogen atmosphere to enhance anaerobic digestion of chicken manure. The only difference between this comparative example and Example 1 is that the peanut shell biochar in this comparative example is prepared under a nitrogen atmosphere to obtain peanut shell biochar N650.

[0049] Comparative Example 2

[0050] This comparative example provides a method for preparing peanut shell biochar under a nitrogen atmosphere to enhance anaerobic digestion of chicken manure. The only difference between this comparative example and Example 1 is that the peanut shell biochar is prepared in a nitrogen atmosphere at a pyrolysis temperature of 750°C to obtain peanut shell biochar N750.

[0051] Comparative Example 3

[0052] This comparative example provides a method for preparing peanut shell biochar under a nitrogen atmosphere to enhance anaerobic digestion of chicken manure. The only difference between this comparative example and Example 1 is that the peanut shell biochar in this comparative example is prepared under a nitrogen atmosphere at a pyrolysis temperature of 850°C to obtain peanut shell biochar N850.

[0053] The peanut shell biochar prepared in Examples 1-3 and Comparative Examples 1-3 and their effects on enhancing anaerobic digestion of chicken manure were investigated.

[0054] 1. The surface morphology of the peanut shell biochar prepared in Examples 1-3 and Comparative Examples 1-3 was observed using a scanning electron microscope (SEM) (Zeiss 360., Germany) at a magnification of 2000 times.

[0055] Scanning electron microscopy results Figures 1-6 As shown in Figure 2, the pyrolysis atmosphere and temperature have a significant effect on the surface morphology of peanut shell biochar. At 650 ° C, the C650 sample prepared in CO2 atmosphere is better than that prepared in The surface of the N650 sample prepared under a CO2 atmosphere exhibited a distinct honeycomb structure, indicating that the CO2 atmosphere promoted the decomposition of organic compounds and the formation of a porous structure. As the pyrolysis temperature increased, the internal structure of the biochar further decomposed, and a large amount of pyrolysis gases were released, resulting in an increase in surface cracks and a more developed pore structure. In particular, at 850°C, the C850 sample prepared under a CO2 atmosphere exhibited the roughest surface morphology. This phenomenon is attributed to the fact that CO2 not only enhances the release of volatiles at high temperatures but also acts as an activator to participate in the reorganization of the carbon skeleton, thereby significantly increasing the porosity and specific surface area of ​​the biochar. Therefore, high-temperature pyrolysis in a CO2 atmosphere (such as 850°C) can effectively optimize the porous structure of peanut shell biochar, providing it with superior physical properties for applications in fields such as adsorption or catalysis.

[0056] 2. The C, H, O, and N contents of the peanut shell biochars prepared in Examples 1-3 and Comparative Examples 1-3 were determined using an elemental analyzer (UNICUBE).

[0057] Table 2

[0058]

[0059] The results are shown in Table 2. During the pyrolysis process of biochar, CO2 acts as an oxidant, accelerating the carbonization process and converting oxygen-containing functional groups to carbonyl groups. It also causes the oxidation loss of some carbon elements. This results in the following characteristics of the final product: (1) a decrease in carbon and nitrogen content and an increase in oxygen content; (2) an increase in the O / C and (N+O) / C atomic ratios; and (3) an enrichment of oxygen-containing functional groups such as surface hydroxyl groups. These structural characteristics significantly enhance the adsorption capacity of biochar for organic pollutants such as AN and VFA.

[0060] 3. The specific surface area and pore size distribution of the peanut shell biochar prepared in Examples 1-3 and Comparative Examples 1-3 were measured using a fully automatic specific surface area and pore size analyzer (Micron 3flex).

[0061] The specific surface area is the ratio between the total surface area of ​​biochar and the total particle mass, which is usually determined by Brunauer-Emmett-Teller (BET) analysis. The mesopore volume (PV) and specific surface area (SA) of biochar produced under different pyrolysis conditions are shown in Figure 2. Figure 7 As shown in Figure 2, under N2 atmosphere, as the pyrolysis temperature increases, the specific surface area gradually decreases, which are 190.7399, 104.1782, and 35.1869 m2, respectively. 2 / g, while the mesopore volume showed a downward trend. This indicates that high temperature in nitrogen atmosphere can lead to the escape of volatile substances, resulting in the reduction of pore structure, thereby reducing the specific surface area and porosity.

[0062] Under a CO2 atmosphere, the specific surface area exhibits a different trend than that under an N2 atmosphere: it increases with increasing temperature. Simultaneously, the mesopore volume also shows an upward trend. This is related to the activation effect of the CO2 atmosphere. At high temperatures, CO2 chemically reacts with the carbon material, forming more pores, significantly increasing the specific surface area and porosity. CO2, acting as an activating agent, promotes the formation and expansion of pores.

[0063] 4. The surface functional group structures of the peanut shell biochars prepared in Examples 1-3 and Comparative Examples 1-3 were analyzed by FTIR (Thermo Fisher Nicolet iS 5 FT-IR).

[0064] Take 1~2 mg of powder sample and 200 mg of pure KBr, grind them evenly, put them in a mold, press them into a transparent thin sheet on a hydraulic press, and put the sample into an infrared spectrometer for testing. The wave number range is 4000~400 cm -1 , scan times 32, resolution 4cm -1 .

[0065] FT-IR spectra of peanut shell biochar produced under different pyrolysis conditions are as follows: Figure 8 As shown, at 3400-3700 cm -1 The absorption peaks in the range of 1300-1750 cm correspond to the stretching vibration of OH, which is mainly attributed to carboxylic acid, hydroxyl and phenol. -1 The absorption peaks identified in the interval are attributed to C=O stretching vibration (aldehydes) and aromatic ring C=C skeleton vibration. The characteristic peaks of functional groups of biochar prepared under N2 atmosphere weakened with increasing temperature, which shows that temperature has a significant effect on the pyrolysis process of biochar, and the pyrolysis reaction of biochar under high temperature conditions is more complete. Although the biochar prepared under the two atmospheres have similar functional group types, the characteristic peak intensity of oxygen-containing functional groups of the product under CO2 atmosphere is significantly higher. Under CO2 atmosphere, the sample after high temperature treatment has a peak at 1096 cm -1 It shows more prominent and sharper peaks.-1 The large peaks near 799 cm are due to aliphatic and aromatic CO stretching of alcohol, ether and ester groups. -1 The out-of-plane bending vibration characteristics of aromatic CH were observed. This may be because CO2 as an atmosphere is conducive to the carbonation reaction of biochar, interacting with the active carbon sites in the biomass at high temperature, promoting the formation and stabilization of oxygen-containing structures.

[0066] 5. During the anaerobic digestion of chicken manure bioaugmented with peanut shells prepared in Examples 1-3 and Comparative Examples 1-3, the daily CH4 production was automatically recorded by the AMPTS II system.

[0067] like Figure 9 The results show the effects of peanut shell biochar prepared under different atmospheres and pyrolysis temperatures on the methane production performance of anaerobic digestion of chicken manure. The results showed that all biochar additions significantly increased methane production, with the most significant improvement achieved by biochar prepared at 850°C under a CO2 atmosphere, reaching a peak methane yield of 26.95 mL / gTS, an 85.7% increase compared to the control. The methane production enhancement effect of biochar prepared under a CO2 atmosphere increased with increasing pyrolysis temperature, while the stimulating effect of biochar prepared under a N2 atmosphere was greatest at 750°C. This difference may be related to the higher specific surface area, richer pore structure, and more oxygen-containing functional groups formed by high-temperature pyrolysis under a CO2 atmosphere. These properties not only provide favorable attachment sites for microorganisms but also enhance electron transfer capacity, thereby optimizing the metabolic activity of methanogens. Furthermore, biochar prepared under a CO2 atmosphere, likely due to its oxidative properties, forms more surface functional groups during pyrolysis, further promoting anaerobic digestion.

[0068] The dynamics of methane production revealed that all experimental groups reached a peak after 3-5 days and then gradually declined. However, the biochar-added groups, especially the C850 group, showed a more gradual decline, with a slight rebound occurring later in the experiment (days 14-15). This suggests that biochar not only increases methane production but also prolongs the system's stable methanogenesis period, likely due to its combined effects of buffering pH, adsorbing inhibitory intermediates, and continuously providing electron transfer pathways. In contrast, methane production in the control group declined rapidly in the later stages, further confirming the important role of biochar in maintaining system stability. Overall, biochar prepared by high-temperature pyrolysis under a CO2 atmosphere exhibits optimal performance in promoting methane production from anaerobic digestion of chicken manure due to its unique physical and chemical properties, providing important insights into the application of biochar in the resource utilization of organic waste.

[0069] like Figure 10As shown, biochar addition significantly increased cumulative methane production over 15 days in all treatments. Biochar prepared at 850°C in a CO2 atmosphere exhibited the greatest improvement, reaching a final cumulative methane production of 144.73 mL / gTS, a 25.8% increase compared to the control (115.08 mL / gTS). Notably, this group exhibited rapid methane accumulation on days 3-4, with a daily increase of 26.95 mL / gTS, indicating that biochar prepared in a high-temperature CO2 atmosphere significantly accelerated the start-up phase of anaerobic digestion. This phenomenon may be due to the more developed pore structure (particularly an increased proportion of mesopores) and abundant surface oxygen-containing functional groups in biochar formed by high-temperature pyrolysis in a CO2 atmosphere. These properties not only provide an ideal microbial niche for methanogens but also optimize microbial synergy by enhancing direct interspecies electron transfer.

[0070] Cumulative methane production kinetics revealed a typical three-stage methane accumulation curve across all experimental groups: a rapid start-up period (0-4 days), a stable gas production period (5-10 days), and a decay period (11-15 days). Compared to the control group, the biochar-added group maintained a longer stable gas production period, and the CO2 atmosphere group exhibited a more gradual decay slope. In particular, the C850℃ group maintained an average methane production rate of 2.07 mL / gTS / d during the later stages (12-15 days), while the control group's methane production rate had dropped to 0.49 mL / gTS / d during the same period. This sustained enhancement may be attributed to the multiple functions of biochar: first, its well-developed pore structure effectively adsorbs inhibitory intermediates such as volatile fatty acids; second, its abundant surface functional groups provide redox-active sites, continuously mediating electron transfer; and third, its high ash content provides essential trace elements such as potassium and calcium. Comparing biochar prepared under different conditions, CO₂ atmosphere generally outperformed samples prepared under N₂ atmosphere. This is likely due to the Boudouard reaction (CO₂ + C → 2CO) that occurs during CO₂ pyrolysis. This reaction effectively etches the carbon skeleton to form more mesopores and increase surface defect sites. These findings provide a theoretical basis for optimizing anaerobic digestion performance by precisely controlling biochar preparation parameters.

Claims

1. A method for preparing peanut shell biochar for enhancing anaerobic digestion of chicken manure under a carbon dioxide atmosphere, characterized in that: Here are the steps: Step 1: Place the dried and crushed peanut shells in a carbon dioxide atmosphere, heat them to a pyrolysis temperature at a certain heating rate, keep them warm for a certain period of time, and then cool them to room temperature to obtain peanut shell biochar; Step 2: Mix the chicken manure and inoculum as the anaerobic digestion substrate, add peanut shell biochar and mix well; Step 3: Establish an anaerobic environment, seal it and run it under intermittent stirring conditions for 15 days until gas production stops, thus completing the anaerobic digestion of chicken manure.

2. The method for preparing peanut shell biochar for enhancing anaerobic digestion of chicken manure under a carbon dioxide atmosphere according to claim 1, characterized in that: The drying in step 1 is oven drying at 105° C., and the particle size of the peanut shell powder is 60 mesh.

3. The method for preparing peanut shell biochar for enhancing anaerobic digestion of chicken manure under a carbon dioxide atmosphere according to claim 1 or 2, characterized in that: The flow rate of the carbon dioxide gas is 400 mL / min.

4. The method for preparing peanut shell biochar for enhancing anaerobic digestion of chicken manure under a carbon dioxide atmosphere according to claim 3, characterized in that: The heating rate in step 1 is 5°C / min, and the pyrolysis temperature is 650-850°C.

5. The method for preparing peanut shell biochar for enhancing anaerobic digestion of chicken manure under a carbon dioxide atmosphere according to claim 4, characterized in that: The holding time of the pyrolysis temperature in step 1 is 2h.

6. The method for preparing peanut shell biochar for enhancing anaerobic digestion of chicken manure under a carbon dioxide atmosphere according to claim 5, characterized in that: The specific surface area of ​​the peanut shell biochar in step 1 is 180.12~409.61 m 2 / g, and the mesopore volume is 0.09~0.20cm 3 / g.

7. The method for preparing peanut shell biochar for enhancing anaerobic digestion of chicken manure under a carbon dioxide atmosphere according to claim 6, characterized in that: In step 2, the chicken manure is mixed with the inoculum at a total solid content ratio of 1:1, and the inoculum is conventional cow dung biogas slurry.

8. The method for preparing peanut shell biochar for enhancing anaerobic digestion of chicken manure under a carbon dioxide atmosphere according to claim 7, characterized in that: The addition amount of peanut shell biochar in step 2 is 15% (w / w) of the total solid content of the fermentation substrate.

9. The method for preparing peanut shell biochar for enhancing anaerobic digestion of chicken manure under a carbon dioxide atmosphere according to claim 8, characterized in that: The reaction temperature of the anaerobic environment in step 3 is 55±1°C.

10. The method for preparing peanut shell biochar for enhancing anaerobic digestion of chicken manure under a carbon dioxide atmosphere according to claim 9, characterized in that: The intermittent stirring condition in step 3 is 80 r / min, 5 min / time.

Images