Method and system for efficiently preparing organic fertilizer from garden waste based on precise environment control and membrane separation

Abstract

The invention relates to the technical field of organic fertilizer preparation, in particular to a method and system for efficiently preparing an organic fertilizer from garden waste based on precise environment control and membrane separation, and the method comprises the following steps: S1, performing classified crushing on garden waste raw materials, and performing impurity sorting after crushing; s2, adding a complex microbial inoculant and a nitrogen source regulator which account for 0.3-0.5 wt% of the total weight of the raw materials into the crushed and sorted raw materials, adjusting the moisture content to 55-60% by spraying, premixing, and standing for 24 hours; s3, the mixed material obtained in the step S2 is fermented, precise environment control is achieved through an intelligent groove type fermentation tank in the fermentation process, and automatic pile turning is conducted once every 24 h; through three-stage precise environment control of the intelligent groove type fermentation tank and use of the complex microbial inoculants, the fermentation period efficiency is improved compared with that of a traditional composting process, solid-liquid efficient separation is achieved through the hollow fiber membrane separation technology, organic fertilizer is prepared from a solid phase, a liquid phase can be recycled as humic acid liquid fertilizer, and the resource utilization rate is effectively increased.

Description

Technical Field

[0001] This invention relates to the field of organic fertilizer preparation technology, specifically to a method and system for efficiently preparing organic fertilizer from garden waste based on precise environmental control and membrane separation. Background Technology

[0002] Garden and landscaping waste mainly originates from urban greening pruning, park and scenic area maintenance, and roadside vegetation management, including fallen leaves, lawn trimmings, and shrub debris. Its annual output exceeds 100 million tons and is showing a year-on-year increasing trend with the accelerating pace of urbanization. Currently, the traditional methods for disposing of this type of waste are open-air composting, incineration, or landfill. Composting has become the mainstream technology due to its ability to achieve resource recycling, but traditional processes have revealed significant limitations in practical applications.

[0003] Traditional composting technology suffers from problems such as a lengthy fermentation cycle (typically 60-90 days), large land area requirements, and low processing efficiency, making it difficult to meet the needs of large-scale processing. Furthermore, the composting process is prone to heavy metal accumulation and excessive soluble salt content, resulting in substandard quality of the finished organic fertilizer. In addition, the uncontrolled release of malodorous gases such as hydrogen sulfide and ammonia during high-temperature fermentation can easily cause air pollution in the surrounding area and lead to environmental disputes.

[0004] Although some improvements have been made in existing technologies, such as optimizing the carbon-nitrogen ratio and adding a single microbial agent, they still cannot simultaneously solve the problems of fermentation efficiency, pollutant control and product quality improvement. There is an urgent need for an innovative technology system that balances high efficiency and environmental friendliness. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for efficiently preparing organic fertilizer from garden waste based on precise environmental control and membrane separation, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for efficiently preparing organic fertilizer from garden waste based on precise environmental control and membrane separation includes the following steps: S1: Classify and crush garden waste raw materials, and then sort out impurities after crushing; S2: Add 0.3-0.5 wt% of compound microbial agent and nitrogen source regulator to the crushed and sorted raw materials, adjust the moisture content to 55-60% by spraying, and let it stand for 24 hours after premixing. S3: Ferment the mixture obtained in step S2. During the fermentation process, a smart trough fermenter is used to achieve precise environmental control, and the mixture is automatically turned over once every 24 hours. S4: The fermentation product obtained in step S3 is subjected to solid-liquid separation using a hollow fiber membrane separator to obtain a solid phase with a water content ≤35% and a humic acid solution with COD ≥20,000 mg / L. S5: Add a passivating agent to the solid phase and mix it, then perform biological rinsing to remove heavy metals from the solid phase; S6: Add trace elements, functional microorganisms and bentonite to the solid phase after step S5 and mix them in a ratio of 0.5-1.0:0.2:3-5wt%. After mixing, dry at 40℃ until the moisture content is ≤20%. After drying, sieve and package.

[0007] As a preferred embodiment of the present invention, the proportion of branches and leaves in the garden waste is ≥70%, and the water content is 40-60%.

[0008] As a preferred embodiment of the present invention, the compound microbial agent includes Trichoderma, Pseudomonas, and nitrogen-fixing bacteria in a ratio of 6:3:1, and the nitrogen source regulator is selected from soybean meal or chicken manure.

[0009] As a preferred embodiment of the present invention, the precision environmental control includes a heating period, a high-temperature period, and a cooling period. The heating period has a temperature of 40-50°C, an oxygen concentration of ≥15%, and a duration of 3-5 days. The high-temperature period has a temperature of 55-65°C, an oxygen concentration of 8-12%, and a duration of 10-12 days. The cooling period has a temperature of 40-45°C, an oxygen concentration of ≥18%, and a duration of 7-8 days.

[0010] As a preferred embodiment of the present invention, the passivating agent comprises 5-8 wt% attapulgite clay and 1-2 wt% calcium dihydrogen phosphate, and the rinsing solution for biological rinsing is a citric acid solution with a concentration of 0.05-0.15 mol / L, a solid-liquid ratio of 1:2-1:4, and a rinsing time of 20-40 min.

[0011] As a preferred embodiment of the present invention, the trace elements in step S6 include Fe, Zn and B, and the functional microbial community adopts arbuscular mycorrhizal fungi.

[0012] As a preferred embodiment of the present invention, step S6 sieving uses a 4mm sieve, and the particle size of the sieved particles is 1-4mm.

[0013] A system for realizing an efficient method of preparing organic fertilizer from garden waste based on precision environmental control and membrane separation includes a crushing and sorting system, an intelligent fermentation tank, a hollow fiber membrane separator, and a scrubbing tower. The intelligent fermentation tank is equipped with a temperature sensor, an oxygen sensor, and a humidity sensor.

[0014] As a preferred embodiment of the present invention, the crushing and sorting system sequentially performs coarse crushing, magnetic separation for iron removal, air separation for plastic removal, and vibrating screening. The coarse crushing adopts a twin-shaft shearing crusher, the magnetic field strength for magnetic separation for iron removal is 0.8-1.0T, the air velocity for air separation for plastic removal is 8-10m / s, and the screen aperture is 5mm.

[0015] As a preferred embodiment of the present invention, the hollow fiber membrane of the hollow fiber membrane separator has a pore size of 0.1-0.2 μm and an operating pressure range of 0.4-0.6 MPa.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention utilizes a three-stage precision environmental control system in an intelligent trough-type fermenter, combined with a compound microbial agent dominated by Trichoderma, to shorten the fermentation cycle to 20-23 days. This improves efficiency compared to traditional composting processes and solves the problems of long processing cycles and low efficiency in garden waste treatment. The synergistic effect of Trichoderma, Pseudomonas, and nitrogen-fixing bacteria in the compound microbial agent, combined with an automatic turning design every 24 hours, increases the lignin degradation rate by 5%, ensuring rapid decomposition of raw materials. This invention uses hollow fiber membrane separation technology to achieve efficient solid-liquid separation. The solid phase is used to prepare organic fertilizer, and the liquid phase can be reused as humic acid liquid fertilizer, thus effectively improving resource utilization. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0018] To facilitate understanding of the present invention, a more complete description will be given below with reference to relevant descriptions. Several embodiments of the invention are provided. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0019] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Example

[0021] A method for efficiently preparing organic fertilizer from garden waste based on precise environmental control and membrane separation includes the following steps: S1: Garden waste with 75% branches and leaves and 50% moisture content is selected as raw material. It is crushed to a particle size of 25mm by a twin-shaft shear crusher, magnetic separation to remove iron with a magnetic field strength of 0.9T and a metal removal rate of 98.5%, air separation to remove plastic with a wind speed of 9m / s and a plastic separation rate of 92%, and vibrating screening with a screen with a 5mm aperture, resulting in a sand and gravel residue rate of 1.8%. S2: Add 0.4wt% of compound microbial agent and nitrogen source regulator based on the total weight of the raw materials to the crushed and sorted raw materials, adjust the moisture content to 58% by spraying, and let it stand for 24 hours after premixing. The compound microbial agent includes Trichoderma, Pseudomonas and nitrogen-fixing bacteria, wherein Trichoderma:Pseudomonas:nitrogenous bacteria = 6:3:1. S3: Use an intelligent trough fermenter to ferment the mixture obtained in step S2, and achieve precise environmental control, including the heating period, high temperature period and cooling period; The warming period lasted 3 days at a temperature of 45°C and an oxygen concentration of 16%. High-temperature period: Temperature 60℃, oxygen concentration 10%, 11 days. Cooling period: temperature 42℃, oxygen concentration 19%, 7 days, automatic turning once every 24 hours; S4: The fermentation product obtained in step S3 is subjected to solid-liquid separation using a hollow fiber membrane separator to obtain a solid phase with a water content ≤35% and a humic acid solution with a COD ≥20,000 mg / L. The pore size of the hollow fiber membrane is 0.1-0.2 μm, the operating pressure range is 0.4-0.6 MPa, the water content of the solid phase after separation is 32%, and the COD of the humic acid solution is 22000 mg / L. S5: Add a passivating agent to the solid phase and mix, then perform biological rinsing to remove heavy metals from the solid phase. The passivating agent is 6wt% attapulgite clay + 1.5wt% calcium dihydrogen phosphate (based on the weight of the solid phase). The biological rinsing uses 0.1mol / L citric acid solution with a solid-liquid ratio of 1:3 and rinsing for 30min. S6: Add trace elements, functional microorganisms and bentonite to the solid phase after step S5 and mix them together. Add 0.8wt% trace elements (Fe:Zn:B=2:1:1, in soluble salt form), 0.2wt% arbuscular mycorrhizal fungi and 4wt% bentonite, dry at 40℃ to a moisture content of 18%, and package after sieving through a 4mm sieve.

[0022] In this embodiment, the fermentation cycle is 21 days, the Pb / Cd solidification rate is 96.2%, the salt removal rate is 88%, and the finished organic fertilizer meets the standard of NY 525-2021. Example

[0023] In step S2, the amount of compound microbial agent added is 0.5 wt%, and the nitrogen source regulator is chicken manure; In step S5, the passivating agent is 8wt% attapulgite clay + 2wt% calcium dihydrogen phosphate, the leaching solution concentration is 0.15mol / L, and the solid-liquid ratio is 1:4.

[0024] In this embodiment, the fermentation cycle was shortened to 20 days, the Pb / Cd solidification rate was 97.5%, the salt removal rate was 90%, but the COD of the humic acid solution was reduced to 19,500 mg / L (because the high concentration of acid solution slightly inhibits the dissolution of organic matter). Example

[0025] The amount of compound microbial agent added in step S2 is 0.3 wt%; In step S5, the passivating agent is 5wt% attapulgite clay + 1wt% calcium dihydrogen phosphate, the leaching solution concentration is 0.05mol / L, and the solid-liquid ratio is 1:2.

[0026] In this embodiment, the fermentation cycle was 23 days, the Pb / Cd solidification rate was 95.0%, the salt removal rate was 86%, and the COD of the humic acid solution was 23000 mg / L (organic matter was more fully dissolved).

[0027] In Example 4, the ratio of the compound microbial agent in step S2 was Trichoderma:Pseudomonas:Diomycosis = 5:3:2 (total addition amount 0.4wt%).

[0028] In this embodiment, the fermentation cycle is 22 days, the lignin degradation rate is increased by 5% (due to an increase in the proportion of Pseudomonas bacteria), but the nitrogen fixation efficiency is slightly reduced by 2%, and the overall organic fertilizer nutrient content meets the standards. This invention verifies the feasibility of the method for preparing organic fertilizer from garden waste through four sets of embodiments, covering the adjustment range of key process parameters, with Pb / Cd solidification rate of 95.0%-97.5% and salt removal rate of 86%-90%, both meeting the organic fertilizer standard of NY 525-2021. Through precise environmental control, optimization of the heating, high-temperature, and cooling periods and microbial agents, the shortest fermentation cycle is 20 days, which is more than 30% shorter than traditional composting. The COD of the humic acid liquid reaches 19,500-23,000 mg / L, which can be reused as liquid fertilizer, realizing the resource utilization of both solid and liquid products. The intelligent trough fermenter has a three-stage environmental control: heating period 40-50℃ → high-temperature period 55-65℃ → cooling period 40-45℃. With the addition of compound microbial agents, the lignin degradation rate is increased by 5%, and the fermentation cycle is shortened to 20-23 days, solving the problem of long cycles in traditional composting.

[0029] Through multiple examples, it has been verified that within the range of parameters such as the amount of compound microbial agent added (0.3-0.5wt%) and the concentration of leaching solution (0.05-0.15mol / L), the method can stably achieve efficient fermentation and pollutant removal, proving its adaptability to different raw material characteristics (such as the proportion of branches and leaves of 70%-100%) and operating conditions.

[0030] Through the synergistic effect of passivating agents and bioleaching, the Pb / Cd solidification rate is ≥95%, avoiding the risk of secondary pollution from heavy metals and meeting the requirements for safe application in farmland. Hollow fiber membrane separation technology achieves efficient solid-liquid separation. The solid phase is used to prepare organic fertilizer, while the liquid phase (COD≥19500mg / L) can be used as humic acid liquid fertilizer, increasing the resource utilization rate to over 90%. The addition of nitrogen source regulators (soybean meal / chicken manure) and bentonite increases the nitrogen, phosphorus, and potassium content of the finished organic fertilizer, meeting the needs of agricultural fertilization.

[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for efficiently preparing organic fertilizer from garden waste based on precise environmental control and membrane separation, characterized in that, The following steps are involved: S1: Classify and crush garden waste raw materials, and then sort out impurities after crushing; S2: Add 0.3-0.5 wt% of compound microbial agent and nitrogen source regulator to the crushed and sorted raw materials, adjust the moisture content to 55-60% by spraying, and let it stand for 24 hours after premixing. S3: Ferment the mixture obtained in step S2. During the fermentation process, a smart trough fermenter is used to achieve precise environmental control, and the mixture is automatically turned over once every 24 hours. S4: The fermentation product obtained in step S3 is subjected to solid-liquid separation using a hollow fiber membrane separator to obtain a solid phase with a water content ≤35% and a humic acid solution with COD ≥20,000 mg / L. S5: Add a passivating agent to the solid phase and mix it, then perform biological rinsing to remove heavy metals from the solid phase; S6: Add trace elements, functional microorganisms and bentonite to the solid phase after step S5 and mix them in a ratio of 0.5-1.0:0.2:3-5wt%. After mixing, dry at 40℃ until the moisture content is ≤20%. After drying, sieve and package.

2. The method for efficiently preparing organic fertilizer from garden waste based on precision environmental control and membrane separation according to claim 1, characterized in that: The garden waste contains ≥70% branches and leaves, and has a moisture content of 40-60%.

3. The method for efficiently preparing organic fertilizer from garden waste based on precision environmental control and membrane separation according to claim 1, characterized in that: The compound microbial agent includes Trichoderma, Pseudomonas, and nitrogen-fixing bacteria in a ratio of 6:3:1, and the nitrogen source regulator is selected from soybean meal or chicken manure.

4. The method for efficiently preparing organic fertilizer from garden waste based on precision environmental control and membrane separation according to claim 1, characterized in that: The precise environmental control includes a heating period, a high-temperature period, and a cooling period. During the heating period, the temperature is 40-50℃, the oxygen concentration is ≥15%, and the duration is 3-5 days. During the high-temperature period, the temperature is 55-65℃, the oxygen concentration is 8-12%, and the duration is 10-12 days. During the cooling period, the temperature is 40-45℃, the oxygen concentration is ≥18%, and the duration is 7-8 days.

5. The method for efficiently preparing organic fertilizer from garden waste based on precision environmental control and membrane separation according to claim 4, characterized in that: The passivating agent comprises 5-8 wt% attapulgite clay and 1-2 wt% calcium dihydrogen phosphate. The leaching solution for bio-leaching is a citric acid solution with a concentration of 0.05-0.15 mol / L, a solid-liquid ratio of 1:2-1:4, and a leaching time of 20-40 min.

6. The method for efficiently preparing organic fertilizer from garden waste based on precision environmental control and membrane separation according to claim 5, characterized in that: The trace elements in step S6 include Fe, Zn, and B, and the functional microbial community uses arbuscular mycorrhizal fungi.

7. A method for efficiently preparing organic fertilizer from garden waste based on precision environmental control and membrane separation according to claim 6, characterized in that: The sieving in step S6 uses a 4mm sieve, and the particle size of the sieved particles is 1-4mm.

8. A system for implementing any one of the methods as described in claims 1-7, characterized in that: It includes a crushing and sorting system, an intelligent fermenter, a hollow fiber membrane separator, and a scrubbing tower. The intelligent fermenter is equipped with a temperature sensor, an oxygen sensor, and a humidity sensor.

9. The system according to claim 8, characterized in that: The crushing and sorting system sequentially performs coarse crushing, magnetic separation for iron removal, air separation for plastic removal, and vibrating screening. The coarse crushing uses a twin-shaft shearing crusher, the magnetic field strength for iron removal is 0.8-1.0T, the air velocity for plastic removal is 8-10m / s, and the screen aperture is 5mm.

10. The system according to claim 8, characterized in that: The hollow fiber membrane of the hollow fiber membrane separator has a pore size of 0.1-0.2μm and an operating pressure range of 0.4-0.6MPa.