Anaerobic fermentation method of pineapple straw

Abstract

The present invention provides a pineapple straw anaerobic fermentation method, which comprises: mixing a pineapple straw material and an inoculum to carry out anaerobic fermentation, the mass ratio of the pineapple straw material to the inoculum is 3: (1.9-2.1), the inoculum comprises a fermentation solid residue obtained by acclimatization treatment of anaerobic bacteria and pineapple straw, and the fermentation solid residue comprises a fermentation solid residue obtained by acclimatization treatment of the anaerobic bacteria and the pineapple straw. The anaerobic strains comprise methanosarcina mazerski, methylobacterium torquefaciens and bacillus amyloliquefaciens. The anaerobic fermentation method of the pineapple straws has the advantages of high fermentation efficiency, short fermentation time and stable biogas yield.

Description

Technical Field

[0001] The invention belongs to the technical field of straw fermentation, and in particular relates to an anaerobic fermentation method of pineapple straw. Background Art

[0002] With the rapid development of agriculture, a large amount of straw has been produced. Straw contains a large amount of organic matter. By treating straw with anaerobic fermentation technology, agricultural waste can be converted into biogas energy. The generated biogas residue and biogas liquid can also be reused as organic fertilizer, which has positive significance for alleviating energy shortages and reducing environmental pressure. The content of cellulose, hemicellulose and lignin in straw is high, among which the content of cellulose is 30%-45%, the content of hemicellulose is 25%-40%, and the content of lignin is 10%-20%. Cellulose, hemicellulose and lignin are difficult to degrade during anaerobic fermentation, which limits the large-scale application of straw anaerobic fermentation. Mixing straw with sludge and feces for anaerobic fermentation can help adjust the carbon-nitrogen ratio of the anaerobic fermentation system and improve the efficiency of anaerobic fermentation.

[0003] As an important agricultural waste in southern Fujian, pineapple straw contains a lot of acidic substances, which leads to acidification of the fermentation liquid and inhibits gas production, thereby reducing the efficiency of anaerobic fermentation. "The effect of dry matter concentration on biogas production by dry anaerobic fermentation of pineapple leaf residue" discloses that pineapple leaf residue is used as raw material, and sludge and pig manure are fermented to cultivate bacteria for anaerobic fermentation to produce biogas. However, the anaerobic fermentation rate is slow, the time is long, and the biogas production is unstable.

[0004] Therefore, it is necessary to provide an anaerobic fermentation method of pineapple straw with high fermentation efficiency, short fermentation time and stable biogas production. Summary of the invention

[0005] The invention provides an anaerobic fermentation method for pineapple straws. The anaerobic fermentation method has the advantages of high fermentation efficiency, short fermentation time and stable biogas production.

[0006] The present invention provides a pineapple straw anaerobic fermentation method, comprising: mixing pineapple straw material and inoculum for anaerobic fermentation;

[0007] The mass ratio of the pineapple straw material to the inoculum is 3:(1.9-2.1);

[0008] The inoculum includes fermentation solid residues obtained by acclimating anaerobic bacteria and pineapple straw;

[0009] The anaerobic bacteria include Methanosarcina mazei, Methylobacterium torsion, and Bacillus amyloliquefaciens.

[0010] The anaerobic fermentation method as described above, wherein, among the anaerobic bacteria, the bacterial population ratio of Methanosarcina, Methylobacterium torsion and Bacillus amyloliquefaciens is 1:(1-2):(3-5).

[0011] The anaerobic fermentation method as described above, wherein the pH value of the anaerobic fermentation is 6.8-7.2.

[0012] The anaerobic fermentation method as described above, wherein the temperature of the anaerobic fermentation is 30-55° C.; and / or,

[0013] The anaerobic fermentation time is 6-8 days.

[0014] The anaerobic fermentation method as described above, wherein the preparation method of the pineapple straw material comprises the following steps: crushing and screening the pineapple straw to obtain pineapple straw particles, and soaking the pineapple straw particles to obtain the pineapple straw material.

[0015] The anaerobic fermentation method as described above, wherein the particle size of the pineapple straw particles is 1.6 mm-2 mm.

[0016] The anaerobic fermentation method as described above, wherein the process of soaking the pineapple straw particles comprises: mixing the pineapple straw particles with water to make the moisture content of the pineapple straw particles be 80%-85%, and then adding an inorganic nitrogen source to mix to obtain the pineapple straw material.

[0017] The anaerobic fermentation method as described above, wherein the pH value of the pineapple straw material is 7-8.

[0018] In the anaerobic fermentation method as described above, the inorganic nitrogen source includes at least one of urea, ammonium salt and nitrate.

[0019] The anaerobic fermentation method as described above, wherein the mass of the urea is 5%-6% of the absolute dry mass of the pineapple straw particles; and / or,

[0020] The mass of the ammonium salt is 0.5%-3% of the absolute dry mass of the pineapple straw particles; and / or,

[0021] The mass of the nitrate is 3%-4% of the absolute dry mass of the pineapple straw particles.

[0022] The anaerobic fermentation method of pineapple straws of the present invention has the advantages of high fermentation efficiency, short fermentation time and stable biogas production. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The invention provides an anaerobic fermentation method of pineapple straw, comprising: mixing pineapple straw material and inoculum for anaerobic fermentation, wherein the mass ratio of the pineapple straw material to the inoculum is 3:(1.9-2.1), and the inoculum comprises fermentation solid residues obtained by acclimating anaerobic bacteria and pineapple straw; the anaerobic bacteria comprises Methanosarcina mazei, Methylobacterium tortuosity, and Bacillus amyloliquefaciens.

[0025] The present invention mixes pineapple straw with a specific inoculant to achieve an efficient anaerobic fermentation process. The anaerobic fermentation method of pineapple straw has the advantages of high fermentation efficiency, short fermentation time, and stable biogas production. Specifically, the mass ratio of pineapple straw to inoculant is 3:(1.9-2.1), and the inoculant is a fermentation solid residue obtained by acclimating anaerobic bacteria and pineapple straw, wherein the anaerobic bacteria include Methanosarcina mazei, Methylobacterium tortuosity, and Bacillus amyloliquefaciens, and the anaerobic fermentation efficiency of pineapple straw is improved through synergistic effect, the fermentation time is shortened, and the biogas production is stabilized.

[0026] The mass ratio of the pineapple straw material and the inoculant in the present invention refers to the ratio of the absolute dry mass of the pineapple straw material to the absolute dry mass of the inoculant.

[0027] Exemplarily, the mass ratio of pineapple straw material to inoculant can be 3:1.9, 3:1.95, 3:2, 3:2.05 or 3:2.1, etc.

[0028] The present invention further improves the anaerobic fermentation efficiency of pineapple straw and shortens the fermentation time by screening the bacterial population ratio of Methanosarcina mazei, Methylobacterium tortuosity and Bacillus amyloliquefaciens.

[0029] In some embodiments, the bacterial population ratio of Methanosarcina mazei, Methylobacterium tortuosity, and Bacillus amyloliquefaciens is 1:(1-2):(3-5).

[0030] Illustratively, the bacterial population ratio of Methanosarcina mazei, Methylobacterium twistothomyceti, and Bacillus amyloliquefaciens can be 1:1:3, 1:1.5:3, 1:2:3, 1:1:4, 1:1.5:4, 1:2:4, 1:1:5, 1:1.5:5 or 1:2:5, etc.

[0031] In some embodiments, the pH value of anaerobic fermentation is 6.8-7.2. The acidic substances produced during anaerobic fermentation cause the pH value of the system to decrease, affecting the growth and metabolism of microorganisms. Therefore, it is necessary to regularly detect the pH value and adjust it in time to keep it between 6.8-7.2.

[0032] Exemplarily, the pH value of anaerobic fermentation can be 6.8, 6.9, 7, 7.1 or 7.2, etc.

[0033] In the present invention, the temperature of anaerobic fermentation is 30-55°C and the time of anaerobic fermentation is 6-8 days, so as to achieve the best anaerobic fermentation effect and economy.

[0034] In some embodiments, the constant temperature in the fermenter is maintained by heating the fermenter. When the average value of the gas production rate for 5 consecutive days is less than 1000 mL / d, the anaerobic fermentation is considered to be complete.

[0035] According to the technical solution of the present invention, the preparation method of pineapple straw material comprises the following steps: crushing and screening the pineapple straw to obtain pineapple straw particles, and soaking the pineapple straw particles to obtain pineapple straw material.

[0036] In some embodiments, the particle size of the pineapple straw particles is 1.6 mm-2 mm, which helps to evenly mix the material with the inoculum and ensure that the anaerobic bacteria can be evenly distributed throughout the fermentation system, thereby achieving a more uniform fermentation process.

[0037] For example, the particle size of the pineapple straw particles may be 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm or 2 mm, etc.

[0038] In the present invention, the process of soaking the pineapple straw particles comprises mixing the pineapple straw particles with water to make the moisture content of the pineapple straw particles be 80%-85%, and then adding an inorganic nitrogen source to mix to obtain a pineapple straw material.

[0039] Illustratively, during the soaking process of the pineapple straw particles, the moisture content of the pineapple straw particles can be 80%, 81%, 82%, 83%, 84% or 85%, etc.

[0040] In some embodiments, the pH value of the pineapple straw material is 7-8, which helps to maintain the growth and metabolic activities of these microorganisms, thereby improving the fermentation efficiency.

[0041] Exemplarily, the pH value of the pineapple straw material can be 7, 7.2, 7.4, 7.6, 7.8 or 8, etc.

[0042] In some embodiments, the inorganic nitrogen source includes at least one of urea, ammonium salt, and nitrate. By adding an inorganic nitrogen source, the nitrogen in the fermentation system can be supplemented to support the reproduction and activity of microorganisms, and can be quickly absorbed and utilized by microorganisms to promote the growth and fermentation efficiency of anaerobic bacterial species. Among them, ammonium salts can release hydrogen ions or hydroxide ions during dissolution and metabolism, which has a buffering effect on the pH value of the anaerobic fermentation system, which is conducive to maintaining a suitable fermentation environment.

[0043] In a specific implementation, the ammonium salt may include one or more of ammonium carbonate, ammonium chloride, and ammonium nitrate, and the nitrate may include potassium nitrate and / or sodium nitrate.

[0044] The present invention can screen the mass percentage content of the inorganic nitrogen source, further promote the growth of the anaerobic bacteria community, and improve the fermentation efficiency.

[0045] In some embodiments, the mass of urea is 5%-6% of the absolute dry mass of the pineapple straw particles.

[0046] Exemplarily, the mass of urea is 5%, 5.2%, 5.4%, 5.6%, 5.8% or 6% of the absolute dry mass of the pineapple straw particles.

[0047] In some embodiments, the mass of the ammonium salt is 0.5%-3% of the absolute dry mass of the pineapple straw particles.

[0048] Exemplarily, the mass of the ammonium salt is 0.5%, 1%, 1.5%, 2%, 2.5% or 3% of the absolute dry mass of the pineapple straw particles.

[0049] In some embodiments, the mass of nitrate is 3%-4% of the absolute dry mass of the pineapple straw particles.

[0050] Exemplarily, the mass of nitrate is 3%, 3.2%, 3.4%, 3.6%, 3.8% or 4% of the absolute dry mass of the pineapple straw particles.

[0051] Hereinafter, the present invention will be further described in detail through specific examples.

[0052] The strains used in the examples and comparative examples of the present invention were purchased from China General Microbiological Culture Collection Center:

[0053] Methanosarcina mazei: CGMCC 1.5193

[0054] Methylobacterium tomentosa: CGMCC 1.6987

[0055] Bacillus amyloliquefaciens: CGMCC 1.857.

[0056] Example 1

[0057] The anaerobic fermentation method of pineapple straw provided in this embodiment comprises the following steps:

[0058] (1) crushing pineapple straw to form initial pineapple straw particles, and then screening the initial pineapple straw particles to obtain pineapple straw particles with a particle size of 1.6 mm to 2 mm;

[0059] (2) putting pineapple straw particles into water and mixing them until the moisture content of the pineapple straw particles is 80%, adding ammonium carbonate, urea and potassium nitrate, and mixing for 60 minutes to obtain pineapple straw material;

[0060] The content of ammonium carbonate is 0.8% of the dry weight of the pineapple straw particles, the content of urea is 5% of the dry weight of the pineapple straw particles, the content of potassium nitrate is 3% of the dry weight of the pineapple straw particles, and the pH value of the pineapple straw material is 7.6;

[0061] (3) mixing the anaerobic bacteria and the pineapple straw particles in step (1) at a mass ratio of 1:1000, and acclimating them at 120 rpm and 35° C. for 7 days to obtain a first fermentation solid residue, and mixing the first fermentation solid residue with the pineapple straw material at a mass ratio of 1:10 at 25° C. and 80 rpm for fermentation, and obtaining a second fermentation solid residue after methane completely stops, and using the second fermentation solid residue as an inoculum;

[0062] The anaerobic bacteria species included Methanosarcina mazei, Methylobacterium tortuosity, and Bacillus amyloliquefaciens, and the bacterial population ratio of Methanosarcina mazei, Methylobacterium tortuosity, and Bacillus amyloliquefaciens was 1:1.5:4;

[0063] (4) Clean and disinfect the fermentation tank to ensure that the fermentation tank is in a sterile state, and add 9 kg of the pineapple straw material obtained in step (2) into the fermentation tank;

[0064] (5) Inoculate 6 kg of the inoculum obtained in step (3) into the fermenter, and perform anaerobic fermentation at 120 rpm and 35° C. for 7 days. Use sodium bicarbonate to adjust the pH of the anaerobic fermentation system to maintain the pH of the anaerobic fermentation system at 6.8.

[0065] Example 2

[0066] The anaerobic fermentation method of pineapple straw provided in this embodiment comprises the following steps:

[0067] (1) crushing pineapple straw to form initial pineapple straw particles, and then screening the initial pineapple straw particles to obtain pineapple straw particles with a particle size of 1.6 mm to 2 mm;

[0068] (2) putting pineapple straw particles into water and mixing them until the moisture content of the pineapple straw particles is 85%, adding ammonium carbonate and urea, and mixing for 90 minutes to obtain pineapple straw material;

[0069] The content of ammonium carbonate is 0.7% of the dry weight of the pineapple straw pellets, the content of urea is 6% of the dry weight of the pineapple straw pellets, and the pH value of the pineapple straw material is 7.4;

[0070] (3) mixing the anaerobic bacteria and the pineapple straw particles in step (1) at a mass ratio of 1:1000, and acclimating the mixture at 120 rpm and 35° C. for 6 days to obtain a first fermentation solid residue, mixing the first fermentation solid residue with the pineapple straw material at a mass ratio of 1:10 for fermentation, and obtaining a second fermentation solid residue after gas production completely stops, and using the second fermentation solid residue as an inoculum;

[0071] The anaerobic bacteria species included Methanosarcina mazei, Methylobacterium tortuosity, and Bacillus amyloliquefaciens, and the bacterial population ratio of Methanosarcina mazei, Methylobacterium tortuosity, and Bacillus amyloliquefaciens was 1:1.5:4;

[0072] (4) Clean and disinfect the fermentation tank to ensure that the fermentation tank is in a sterile state, and add 9 kg of the pineapple straw material obtained in step (2) into the fermentation tank;

[0073] (5) Inoculate 5.7 kg of the inoculum obtained in step (3) into the fermenter, and perform anaerobic fermentation at 120 rpm and 35° C. for 6 days. Use sodium bicarbonate to adjust the pH of the anaerobic fermentation system to maintain the pH of the anaerobic fermentation system at 7.

[0074] Example 3

[0075] The anaerobic fermentation method of pineapple straw provided in this embodiment comprises the following steps:

[0076] (1) crushing pineapple straw to form initial pineapple straw particles, and then screening the initial pineapple straw particles to obtain pineapple straw particles with a particle size of 1.6-2 mm;

[0077] (2) putting pineapple straw particles into water and mixing them until the moisture content of the pineapple straw particles is 85%, adding ammonium carbonate and sodium nitrate, and mixing for 90 minutes to obtain pineapple straw material;

[0078] The content of ammonium carbonate is 0.7% of the dry weight of the pineapple straw pellets, the content of sodium nitrate is 4% of the dry weight of the pineapple straw pellets, and the pH value of the pineapple straw material is 7.2;

[0079] (3) mixing the anaerobic bacteria and the pineapple straw particles in step (1) at a mass ratio of 1:1000, and acclimating the mixture at 120 rpm and 35° C. for 8 days to obtain a first fermentation solid residue, mixing the first fermentation solid residue with the pineapple straw material at a mass ratio of 1:10 for fermentation, and obtaining a second fermentation solid residue after gas production completely stops, and using the second fermentation solid residue as an inoculum;

[0080] The anaerobic bacteria species included Methanosarcina mazei, Methylobacterium tortuosity, and Bacillus amyloliquefaciens, and the bacterial population ratio of Methanosarcina mazei, Methylobacterium tortuosity, and Bacillus amyloliquefaciens was 1:2:5;

[0081] (4) Clean and disinfect the fermentation tank to ensure that the fermentation tank is in a sterile state, and add 9 kg of the pineapple straw material obtained in step (2) into the fermentation tank;

[0082] (5) Inoculate 6.3 kg of the inoculum obtained in step (3) into the fermenter, and perform anaerobic fermentation at 120 rpm and 35° C. for 8 days. Use sodium bicarbonate to adjust the pH of the anaerobic fermentation system to maintain the pH of the anaerobic fermentation system at 7.2.

[0083] Example 4

[0084] The anaerobic fermentation method of pineapple straw provided in this embodiment is basically the same as that in embodiment 1, except that: in step (2), the pineapple straw particles are placed in water and mixed to adjust the moisture content of the pineapple straw particles to 85%, and urea is added and mixed for 90 minutes to obtain a pineapple straw material, in which the urea content is 6% of the dry weight of the pineapple straw particles.

[0085] Example 5

[0086] The anaerobic fermentation method of pineapple straw provided in this embodiment is basically the same as that in embodiment 1, except that: in step (2), the pineapple straw particles are placed in water, a first mixing is performed to make the moisture content of the pineapple straw particles 80%, ammonium carbonate, urea and potassium nitrate are added, and a second mixing is performed for 60 minutes to obtain a pineapple straw material;

[0087] The content of ammonium carbonate is 0.4% of the dry weight of the pineapple straw pellets, the content of urea is 4% of the dry weight of the pineapple straw pellets, and the content of potassium nitrate is 2% of the dry weight of the pineapple straw pellets.

[0088] Example 6

[0089] The anaerobic fermentation method of pineapple straw provided in this embodiment is basically the same as that in embodiment 1, except that the bacterial population ratio of Methanosarcina mazei, Methylobacterium tortuosity, and Bacillus amyloliquefaciens is 1:1:3.

[0090] Comparative Example 1

[0091] The anaerobic fermentation method of pineapple straw provided in this comparative example is basically the same as that in Example 1, except that: in step (4), 9 kg of pineapple straw material obtained in step (2) is loaded into the fermentation tank; in step (5), 4.5 kg of the inoculum obtained in step (3) is inoculated into the fermentation tank.

[0092] Comparative Example 2

[0093] The anaerobic fermentation method of pineapple straw provided in this comparative example is basically the same as that in Example 1, except that in step (3), the anaerobic bacteria only include Methanosarcina mazei.

[0094] Comparative Example 3

[0095] The anaerobic fermentation method of pineapple straw provided in this comparative example is basically the same as that in Example 1, except that in step (3), the anaerobic bacteria only include Methylobacterium tomentosum.

[0096] The methane production rate per unit of raw material refers to the volume of methane produced by unit mass of solid raw material.

[0097] Table 1

[0098]

[0099] Analysis of Table 1 shows that, compared with Comparative Examples 1-3, Examples 1-6 have a higher methane content per unit volume of biogas, indicating that the anaerobic fermentation method of pineapple straw in Examples 1-6 has the advantages of high fermentation efficiency and short fermentation time.

[0100] Among them, it should be explained at the end that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or part or all of the technical features can be replaced by equivalents. These modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present invention.

Claims

1. An anaerobic fermentation method for pineapple straw, characterized in that: include: The pineapple straw material and the inoculum are mixed for anaerobic fermentation; The mass ratio of the pineapple straw material to the inoculum is 3:(1.9-2.1); The inoculum includes fermentation solid residues obtained by acclimating anaerobic bacteria and pineapple straw; The anaerobic bacteria include Methanosarcina mazei, Methylobacterium torsion, and Bacillus amyloliquefaciens.

2. The anaerobic fermentation method according to claim 1, characterized in that: Among the anaerobic bacteria, the bacterial population ratio of Methanosarcina, Methylobacterium torsion and Bacillus amyloliquefaciens is 1:(1-2):(3-5).

3. The anaerobic fermentation method according to claim 1 or 2, characterized in that: The pH value of the anaerobic fermentation is 6.8-7.

2.

4. The anaerobic fermentation method according to claim 1, characterized in that: The temperature of the anaerobic fermentation is 30-55°C; and / or, The anaerobic fermentation time is 6-8 days.

5. The anaerobic fermentation method according to claim 1, characterized in that: The preparation method of the pineapple straw material comprises the following steps: crushing and screening the pineapple straw to obtain pineapple straw particles, and soaking the pineapple straw particles to obtain the pineapple straw material.

6. The anaerobic fermentation method according to claim 5, characterized in that: The particle size of the pineapple straw particles is 1.6 mm to 2 mm.

7. The anaerobic fermentation method according to claim 5, characterized in that: The process of soaking the pineapple straw particles comprises: mixing the pineapple straw particles with water to make the moisture content of the pineapple straw particles be 80%-85%, and then adding an inorganic nitrogen source to mix to obtain the pineapple straw material.

8. The anaerobic fermentation method according to claim 1, characterized in that: The pH value of the pineapple straw material is 7-8.

9. The anaerobic fermentation method according to claim 7, characterized in that: The inorganic nitrogen source includes at least one of urea, ammonium salt and nitrate.

10. The anaerobic fermentation method according to claim 9, characterized in that: The mass of the urea is 5%-6% of the absolute dry mass of the pineapple straw particles; and / or, The mass of the ammonium salt is 0.5%-3% of the absolute dry mass of the pineapple straw particles; and / or, The mass of the nitrate is 3%-4% of the absolute dry mass of the pineapple straw particles.

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