Organic fertilizer production method

Abstract

The invention discloses an organic fertilizer production method, and particularly relates to the technical field of organic fertilizer production, and the method comprises the following steps: kitchen garbage is classified according to moisture and fiber content, and is pretreated by extrusion crushing and high-frequency vibration crushing; mixing the pretreated materials in proportion, inoculating a compound microbial agent, and performing efficient fermentation under the condition of intelligent temperature and humidity control; and gelatinizing the fermentation product with sodium alginate and calcium chloride to prepare the slow-release gel particle organic fertilizer. According to the organic fertilizer production method disclosed by the invention, the fermentation period is shortened and the production efficiency is improved through the synergistic effect of quality-divided pretreatment and the complex microbial inoculants; waste and environmental pollution caused by burst release of nutrients are effectively avoided; the product has the characteristics of convenience in application and long-acting slow release, can be directly applied through a drip irrigation system, greatly reduces the labor intensity, and has remarkable economic and environmental benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of organic fertilizer production, in particular to an organic fertilizer production method. Background Art

[0002] With the increasing awareness of environmental protection and the demand for sustainable agricultural development, the production and application of organic fertilizers have received more and more attention. Traditional organic fertilizer production has limited raw material sources and complex processing technology, resulting in high costs. Some production technologies using kitchen waste as raw materials have problems such as cumbersome processing procedures, long fermentation cycles, and unstable product quality.

[0003] The current technical bottlenecks in food waste treatment are as follows: the traditional composting method has a long fermentation cycle and produces foul-smelling gases; mechanical dehydration treatment will result in a large loss of water-soluble nutrients (about 40% nitrogen loss); the finished fertilizer has problems such as clumping and uncontrollable nutrient release.

[0004] A search revealed that CN114315485A, a comparative document, discloses a method for aerobic composting of kitchen waste, its application, and composting. However, this method still suffers from drawbacks such as large fermentation temperature fluctuations and an unresolved nutrient release issue. The present invention achieves a technological breakthrough through an innovative approach combining quality-based pretreatment, precise fermentation, and gel fixation. Summary of the Invention

[0005] The main purpose of the present invention is to provide an organic fertilizer production method, which can effectively solve the three core problems existing in kitchen waste treatment: severe nutrient loss, low fermentation efficiency, and poor product functionality.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for producing organic fertilizer comprises the following steps:

[0008] S1. Raw material classification: fresh kitchen waste is classified into high-water-classified kitchen waste and high-fiber kitchen waste within 24 hours;

[0009] S2. Post-classification pretreatment: crush and squeeze high-water-classified kitchen waste, and collect the squeezed liquid components; crush high-fiber kitchen waste with high-frequency vibration;

[0010] S3, mixed fermentation: the two types of pretreated materials are mixed in a ratio of (2.5-3.5):1, and a composite microbial agent is added for aerobic fermentation;

[0011] S4. Finished product granulation: adding a gel-forming agent to the fermentation product to make gel-like fertilizer granules.

[0012] Preferably, the high-water-classified kitchen waste is kitchen waste with a moisture content ≥70wt%, and the high-fiber kitchen waste is kitchen waste with a crude fiber content ≥15wt%.

[0013] Preferably, in the pretreatment step:

[0014] High-water classification kitchen waste treatment uses a crushing and extrusion machine with a rotation speed of 1400-2200 rpm and an extrusion pressure of 0.3-0.8MPa;

[0015] High-fiber kitchen waste is processed using a high-frequency vibration crusher with a frequency of 25-55Hz, and the crushed particle size is controlled at 2-8mm.

[0016] Preferably, the composite microbial agent is a mixture of Bacillus subtilis, Bacillus amyloliquefaciens and Aspergillus niger, and Bacillus subtilis, Bacillus amyloliquefaciens and Aspergillus niger are compounded in a ratio of (3-5):(2-4):1, and the total addition amount is 0.05-0.5% of the weight of the material.

[0017] Preferably, the fermentation process adopts multi-stage temperature control: the first stage (0-24h): control the temperature at 35-40°C; the second stage (24-72h): control the temperature at 45-55°C; the third stage (after 72h): control the temperature at 50-60°C; during the fermentation period, the porosity of the material is maintained at 30-45% and the oxygen content is ≥15%.

[0018] Preferably, the gel forming agent comprises: 1-4% sodium alginate, 0.5-2.5% calcium chloride, and 0.2-1% modified starch, wherein the percentages are the proportions of each component to the weight of the fermentation product.

[0019] Preferably, the gel fertilizer particles have a particle size of 1-8 mm, a compressive strength of 5-20 N / particle, and a nutrient release rate of 30-60% in water within 24 hours.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. This invention significantly shortens the production cycle of organic fertilizer through the synergistic effect of innovative quality-based pretreatment technology and composite microbial inoculants. Traditional composting methods typically require more than 21 days to complete composting, but this technology, under precise temperature and humidity control conditions, can achieve full composting in just 7 days, improving production efficiency. This efficiency improvement not only reduces time costs but also significantly increases output per unit time, providing technical support for large-scale production.

[0022] 2. This invention's unique combination of an extruded liquid phase recovery system and gel-encapsulation technology reuses the nutrient-rich liquid extruded during the pretreatment stage for humidity control during the fermentation process, preventing the loss of water-soluble nutrients and achieving resource recycling. The formation of gel particles further locks in nutrients, significantly improving fertilizer utilization.

[0023] 3. This invention pioneers the use of 3-5mm gel particles to form organic fertilizer, resolving the pain points of traditional organic fertilizers, which tend to clump and be difficult to apply. These particles possess excellent fluidity and mechanical strength (15-20N / particle), allowing them to be applied directly through drip irrigation systems, significantly reducing labor intensity. More importantly, the gel structure enables the slow release of nutrients, effectively avoiding the waste and environmental pollution caused by sudden nutrient release. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention discloses a flow chart for preparing the organic fertilizer. DETAILED DESCRIPTION

[0025] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0026] like Figure 1 As shown, the present invention discloses a method for producing organic fertilizer, comprising the following steps:

[0027] S1. Raw material classification: fresh kitchen waste is classified into high-water-classified kitchen waste and high-fiber kitchen waste within 24 hours;

[0028] High-water classified kitchen waste refers to kitchen waste with a moisture content ≥70wt%, and high-fiber classified kitchen waste refers to kitchen waste with a crude fiber content ≥15wt%.

[0029] Specifically, in practice, near-infrared spectroscopy (NIRS) sorting equipment is used to establish a rapid identification model for kitchen waste:

[0030] High water classification identification feature: reflectivity >65% at 1450nm.

[0031] High fiber identification characteristics: characteristic absorption peak in the 1900-2200nm band.

[0032] S2. Post-classification pretreatment: crush and squeeze high-water-classified kitchen waste, and collect the squeezed liquid components; crush high-fiber kitchen waste with high-frequency vibration;

[0033] High-water classification kitchen waste treatment uses a crushing and extrusion machine with a rotation speed of 1400-2200 rpm and an extrusion pressure of 0.3-0.8MPa;

[0034] High-fiber kitchen waste is processed using a high-frequency vibration crusher with a frequency of 25-55Hz, and the crushed particle size is controlled at 2-8mm.

[0035] S3, mixed fermentation: the two types of pretreated materials are mixed in a ratio of (2.5-3.5):1, and a composite microbial agent is added for aerobic fermentation;

[0036] The composite microbial agent is a mixture of Bacillus subtilis, Bacillus amyloliquefaciens and Aspergillus niger, and the Bacillus subtilis, Bacillus amyloliquefaciens and Aspergillus niger are compounded in a ratio of (3-5):(2-4):1, and the total addition amount is 0.05-0.5% of the weight of the material.

[0037] In addition, the fermentation process adopts multi-stage temperature control: the first stage (0-24h): control the temperature at 35-40℃; the second stage (24-72h): control the temperature at 45-55℃; the third stage (after 72h): control the temperature at 50-60℃; during the fermentation period, the porosity of the material is maintained at 30-45% and the oxygen content is ≥15%.

[0038] S4, finished product granulation: adding a gel-forming agent to the fermentation product to produce gel-like fertilizer granules;

[0039] The gel forming agent includes: sodium alginate 1-4%, calcium chloride 0.5-2.5%, modified starch 0.2-1%, and the percentage is the proportion of each component to the weight of the fermentation product;

[0040] The formed gel fertilizer particles have the following characteristics: particle size of 1-8 mm, compressive strength of 5-20 N / particle, and nutrient slow-release rate of 30-60% in water within 24 hours.

[0041] The present invention is further disclosed below in conjunction with specific embodiments:

[0042] Example 1 (household kitchen waste treatment)

[0043] Step 1. Raw material collection and classification

[0044] Collect 3kg of household kitchen waste (including fruit peels, vegetable leaves, leftovers, etc.) and sort it within 12 hours:

[0045] High-water category (2.1kg): The water content is ≥75% as tested by a moisture meter, including watermelon peel, tomato residue, etc. High-fiber category (0.9kg): The content is ≥18% as tested by a crude fiber meter, including corn cobs, celery stalks, etc.

[0046] Step 2. Preprocessing

[0047] High-water classification treatment: A small twin-screw extruder (screw diameter 50 mm, aspect ratio 18:1) was used, with a set speed of 1600 rpm and an extrusion pressure of 0.5 MPa to separate 680 ml of liquid phase (filtered through a 200 μm mesh);

[0048] High fiber processing: Use a high-frequency vibration crusher (frequency 35Hz, amplitude 2mm) to crush into 3-5mm fiber segments, and the qualified rate is verified by screening to be ≥90%.

[0049] Step 3. Add compound bacteria and fermentation

[0050] The two types of materials were mixed at a ratio of 3:1, and inoculated with a composite bacterial agent (HY-7:FJ-3:ZX-9 = 4:3:1, with a total addition of 0.2%); placed in an intelligent fermentation box (with a PID temperature control system) and controlled according to the following program:

[0051] 0-24h: Raise the temperature to 45±1°C, with intermittent ventilation (on / off = 5 min / 15 min); 24-72h: Maintain at 55±1°C, with continuous ventilation (0.5 L / min·kg); after 72h: Lower the temperature to 50°C and adjust the humidity to 60% (by spraying the extruded liquid phase).

[0052] Step 4. Gelation and granulation

[0053] Add the following to the decomposed material: sodium alginate (2.5%, w / w, dissolved in the extruded liquid phase); CaCl2 (1.5%, w / w, prepared into a 5% solution); form 3-5 mm gel particles through a drip-crosslinking device (needle diameter 1 mm, drip height 20 cm), and dry with hot air at 60°C to a moisture content of 30%.

[0054] Example 2 (Centralized Treatment of Kitchen Waste)

[0055] Step 1. Industrial sorting and pretreatment

[0056] Sorting system: TOMRA FOOD sorter (near infrared recognition accuracy ≥ 95%), processing capacity 3t / h, sorting out: high-moisture classification (moisture content 72±3%): 2.1 tons; high-fiber classification (crude fiber 20±2%): 0.9 tons;

[0057] Extrusion dehydration: using a two-stage screw extruder (first stage pressure 0.4 MPa, second stage 0.7 MPa), 850 L of liquid phase was extruded (filtered through a ceramic membrane with a molecular weight cut-off of 10 kDa);

[0058] Fiber crushing: Hammer crusher (rotating speed 2800 rpm, sieve hole 3 mm), after crushing, the fiber length ≤ 5 mm accounts for 88%.

[0059] Step 2. Scale-up fermentation

[0060] Inoculation and mixing: put the material into 50m3 at a ratio of 3:1 3 In the fermentation tank, add the compound bacterial agent (total addition amount 0.15%) and mix in 0.8% humic acid;

[0061] Intelligent control: Real-time adjustment through PLC system: temperature: 45-55℃ (±2℃); oxygen concentration: ≥18% (DO sensor feedback control fan); humidity: 55-60% (extruded liquid phase atomization spray).

[0062] Step 3. Continuous granulation process

[0063] Gelation formula: sodium alginate 2.2% + CaCl2 1.3% + 0.3% polyglutamic acid (to enhance water retention); equipment parameters: fluidized bed granulator (inlet temperature 45°C, wind speed 2m / s); particle size distribution: 3-5mm accounts for 85% (detected by laser particle size analyzer).

[0064] Based on the organic fertilizer sample prepared in Example 2, the effect of the organic fertilizer prepared by the present invention was verified according to the following scheme.

[0065] a. Fermentation efficiency comparison experiment

[0066] Experimental purpose: To verify the advantages of the present invention in terms of fermentation cycle, temperature stability and composting efficiency.

[0067] Experimental setup:

[0068] Control group B (commercially available EM bacterial agent group): using commercially available EM bacterial agent (effective viable bacteria count ≥ 1×10 8 CFU / g), inoculated according to the recommended addition amount (0.2%), and the frequency of pile turning was the same as that of the experimental group.

[0069] Experimental group (the present invention): a composite bacterial agent (HY-7:FJ-3:ZX-9=4:3:1) + an intelligent temperature control system was used to adjust the ventilation volume and humidity in real time.

[0070] Detection method:

[0071] Temperature monitoring: An infrared thermal imager (FLIR T1020) was used to record the surface temperature distribution of the pile, and an embedded thermocouple (accuracy ±0.5°C) was used to monitor the core temperature. Data was collected every 2 hours.

[0072] Evaluation indicators: temperature stability (standard deviation), duration of high temperature period (≥50℃).

[0073] Maturity Assessment: Seed Germination Index (GI): 5 g of compost extract (water-to-fertilizer ratio 10:1) was added to sow pakchoy seeds. After incubation at 25°C for 48 hours, the germination rate and root growth inhibition rate were calculated. GI = (germination rate × root length of treatment group) / (germination rate × root length of control group) × 100%. A GI ≥ 80% was considered mature.

[0074] Organic matter degradation rate: The change of total organic carbon (TOC) was determined by potassium dichromate oxidation method, and the degradation rate (% / d) was calculated.

[0075] Ammonia emission reduction effect: An airtight composting reactor was connected to a gas analyzer (INNOVA 1412) to collect ammonia concentration every 12 hours and integrate the accumulated emissions.

[0076] The experimental results are as follows:

[0077] Temperature control: The temperature fluctuation range of the experimental group was ≤±3℃, which was significantly lower than that of the control groups A (±8℃) and B (±5℃).

[0078] Composting time: It took only 7 days for the experimental group to reach 80% GI, which was more than 50% shorter than that of the control groups A (21 days) and B (14 days).

[0079] Ammonia emission reduction: The cumulative ammonia emission of the experimental group was 12.3 mg / kg, which was 62.4% lower than that of the control group A (32.7 mg / kg).

[0080] b. Verification of sustained-release performance

[0081] Experimental methods: 1. Static release kinetics:

[0082] Take 10 gel particles (3-5 mm in diameter) and place them in 200 ml of deionized water at 25°C with constant temperature shaking (100 rpm);

[0083] Samples were taken at 1h, 6h, 12h, 1d, 3d, 7d, 14d, and 21d, and NH4 was determined by continuous flow analyzer (SkalarSAN++) + -N, NO3 - -N、PO4 3 --P concentration;

[0084] The release curve was fitted using the Korsmeyer-Peppas model:

[0085] M t / M ∞ =kt n

[0086] Where n = 0.45 represents Fickian diffusion, and n > 0.89 represents burst release.

[0087] 2. Soil column leaching experiment: A 30-cm-high soil column (filled with sandy loam, bulk density 1.35 g / cm3) was constructed, and 5 g of fertilizer was buried in the surface layer; rainfall was simulated (50 ml of deionized water per day), and the leachate was collected to detect the nutrient content.

[0088] Results: Release half-life (T50): The gel fertilizer of the present invention is 18.7 days, while the common granular fertilizer is only 3.2 days; Leaching loss rate: Within 21 days, the cumulative leaching loss of N and P of the present invention is 12.3 respectively.

[0089] In summary, the present invention is an innovative method for efficiently converting kitchen waste into functional organic fertilizer through the three-in-one technology of quality-based pretreatment, precise fermentation of composite bacterial agents, and gel-controlled release fixation, which has the triple advantages of low cost, high performance, and environmental friendliness.

[0090] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for producing organic fertilizer, characterized in that, The following steps are involved: S1. Raw material classification: fresh kitchen waste is classified into high-water-classified kitchen waste and high-fiber kitchen waste within 24 hours; S2. Post-classification pretreatment: crush and squeeze high-water-content kitchen waste, and collect the squeezed liquid components; crush high-fiber kitchen waste with high-frequency vibration; S3, mixed fermentation: the two types of pretreated materials are mixed in a ratio of (2.5-3.5):1, and a composite microbial agent is added for aerobic fermentation; S4, finished product granulation: adding a gel-forming agent to the fermentation product to make gel-like fertilizer granules.

2. a kind of organic fertilizer production method according to claim 1, is characterized in that: The high-water-classified kitchen waste is kitchen waste with a moisture content of ≥70wt%, and the high-fiber kitchen waste is kitchen waste with a crude fiber content of ≥15wt%.

3. a kind of organic fertilizer production method according to claim 1, is characterized in that: In the pre-processing step: High-water classification kitchen waste treatment uses a crushing and extrusion machine with a rotation speed of 1400-2200 rpm and an extrusion pressure of 0.3-0.8MPa; High-fiber kitchen waste is processed using a high-frequency vibration crusher with a frequency of 25-55Hz, and the crushed particle size is controlled at 2-8mm.

4. a kind of organic fertilizer production method according to claim 1, is characterized in that: The composite microbial agent is a mixture of bacillus subtilis, bacillus amyloliquefaciens and aspergillus niger, and the bacillus subtilis, bacillus amyloliquefaciens and aspergillus niger are compounded in a ratio of (3-5):(2-4):1, and the total addition amount is 0.05-0.5% of the weight of the material.

5. a kind of organic fertilizer production method according to claim 1, is characterized in that: The fermentation process adopts multi-stage temperature control: the first stage (0-24h): the temperature is controlled at 35-40°C; the second stage (24-72h): the temperature is controlled at 45-55°C; the third stage (after 72h): the temperature is controlled at 50-60°C; during the fermentation period, the porosity of the material is maintained at 30-45% and the oxygen content is ≥15%.

6. a kind of organic fertilizer production method according to claim 1, is characterized in that: The gel forming agent comprises: 1-4% sodium alginate, 0.5-2.5% calcium chloride, and 0.2-1% modified starch, wherein the percentages are the proportions of each component to the weight of the fermentation product.

7. a kind of organic fertilizer production method according to claim 1, is characterized in that: The gel fertilizer particles have the following characteristics: particle size of 1-8 mm, compressive strength of 5-20 N / particle, and a nutrient slow-release rate of 30-60% in water within 24 hours.

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