Method for preparing organic fertilizer from garden waste

Abstract

The invention discloses a method for preparing an organic fertilizer by utilizing garden wastes and relates to the field of garden wastes. Comprising the following steps: 1) pretreatment: putting the garden waste into a microwave reactor to react so as to remove a large amount of lignin and retain cellulose; 2) enzymolysis: drying the residues pretreated in the step 1), and carrying out enzymolysis treatment to obtain an enzyme solution as a main nutrient solution required by the growth of microorganisms; (3) detoxifying: adding activated carbon into the enzyme liquid obtained in the step (2) as an adsorbent, and shaking while adding so as to remove toxic substances for inhibiting fermentation; and 4) compost fermentation: sterilizing the solution obtained in the step 3), inoculating bacillus subtilis for culture, and then inoculating into the garden waste for compost fermentation. Compared with traditional compost, the method has the advantages that the fermentation time is greatly shortened, the cost is saved, an innovative and efficient technical scheme is provided for resource utilization of garden wastes, and the method has remarkable ecological and economic benefits.

Description

Technical Field

[0001] The present invention relates to the field of garden waste, and in particular to a method for preparing organic fertilizer by using garden waste. Background Art

[0002] In recent years, with the accelerating process of urbanization construction and the continuous increase of urban garden green space area, the quantity of garden waste has been increasing, becoming one of the main sources of urban solid waste, which brings huge challenges to the current ecological environment construction. The so-called garden waste refers to a series of organic materials including dead branches and fallen leaves (plant litter), including branches, weeds, seeds, and withered flowers, etc. In view of the increasing garden waste, how to realize the reduction, harmlessness, and resource utilization of garden waste, reduce the pollution to the environment, and promote the conversion of waste into valuable resources has become an urgent problem to be solved and a research hotspot in various countries at the present stage.

[0003] For a long time, these garden wastes have often been regarded as solid waste, and the common disposal methods are landfill or incineration. However, both of these methods have led to serious air pollution and resource waste. On the one hand, the landfill of garden waste will lead to the occupation of a large amount of land resources. On the other hand, the incineration of garden waste will release a large amount of greenhouse gases and harmful gases such as sulfur dioxide, causing serious air pollution.

[0004] At present, the annual production of garden waste is large, but the utilization rate is low. Many scholars have conducted a large number of studies on the treatment and reuse of garden waste. The treatment and utilization of garden waste in China mainly focus on the product application of compost: the development and utilization of organic fertilizers, biomass energy, and some biological products. However, the traditional composting fermentation time is long, often taking more than one month to obtain mature compost.

[0005] The present invention provides a method for aerobic composting in a short period to improve the problems of high cost and long time in the composting field, so as to find a reasonable and acceptable solution for the problem of garden waste treatment. Summary of the Invention

[0006] The purpose of the present invention is to solve the above problems in the prior art, and provide a method for preparing organic fertilizer by using garden waste, aiming to solve the problem of garden waste treatment and realize the efficient recycling of resources.

[0007] To achieve the above purpose, the present invention adopts the following technical scheme:

[0008] A method for preparing organic fertilizer by using garden waste, comprising the following steps:

[0009] 1) Pretreatment: Placing the garden waste in a microwave reactor for reaction to remove a large amount of lignin and retain cellulose;

[0010] 2) Enzymatic hydrolysis: Dry the residue after the pretreatment in step 1), perform enzymatic hydrolysis treatment to obtain an enzyme solution as the main nutrient solution required for microbial growth;

[0011] 3) Detoxification: Add activated carbon as an adsorbent to the enzyme solution obtained in step 2), shake while adding to remove the toxic substances that inhibit fermentation;

[0012] 4) Composting fermentation: After sterilizing the solution obtained in step 3), inoculate Bacillus subtilis for cultivation, and then inoculate it into garden waste for composting fermentation.

[0013] The water content of the said garden waste is 15% - 50%.

[0014] In step 1), the microwave power applied to the unit mass of garden waste by the microwave reactor is 100 - 1000 W / kg.

[0015] In step 1), the reaction time of the microwave reactor is 1 - 120 minutes.

[0016] In step 2), the enzyme used for enzymatic hydrolysis treatment is cellulase, and the addition amount of cellulase is 1 - 50 units per gram of residue to ensure that the residue can be fully converted into fermentable sugars by enzymatic hydrolysis.

[0017] In step 2), the time for enzymatic hydrolysis treatment is 36 - 72 hours.

[0018] In step 3), calculated by mass - volume ratio (w / v), the addition amount of activated carbon is 0.1% - 5% of the enzyme solution.

[0019] In step 4), the inoculation amount of the said Bacillus subtilis is 1 - 100 mL per kilogram of garden waste to achieve the optimal composting effect.

[0020] In step 4), the time for inoculating and culturing Bacillus subtilis is 1 - 24 hours.

[0021] In step 4), the temperature for composting fermentation is 25 - 40 °C to provide suitable temperature conditions for the composting process.

[0022] In step 4), the time for composting fermentation is 24 - 240 hours to ensure the full decomposition of the compost and the quality of the organic fertilizer.

[0023] Compared with the prior art, the beneficial effects obtained by the technical solution of the present invention are:

[0024] 1. Pretreatment stage: Use a microwave reactor to treat garden waste. Different from traditional pretreatment methods, it can specifically remove a large amount of lignin while retaining cellulose. By controlling the characteristics of microwaves and the reaction time, a unique material pretreatment effect is achieved, providing a good foundation for subsequent steps.

[0025] 2. Enzymatic hydrolysis step: Through enzymatic hydrolysis operation for a specific duration, convert the residue after pretreatment into fermentable sugars, which serve as the main nutrient solution for the growth of Bacillus subtilis. This innovative method of converting garden waste into the nutrient solution required by bacteria realizes the efficient utilization and resource conversion of waste.

[0026] 3. Detoxification step: Use activated carbon as an adsorbent and, through the operation method of adding while shaking, effectively remove toxic substances such as aldehydes, acids, and phenols that inhibit fermentation in the enzyme solution. This detoxification method is simple and easy to implement and highly targeted, contributing to the smooth progress of the subsequent composting fermentation process.

[0027] 4. Composting fermentation stage: First, inoculate Bacillus subtilis into the detoxified enzyme solution for sterilization and cultivation, and then inoculate it into garden waste for composting. This operation of pre-cultivating bacteria in the enzyme solution is beneficial to adjusting the growth state of bacteria, improving the activity and adaptability of bacteria during the composting process, and providing a new technical idea and operation mode for the entire composting process.

[0028] In summary, compared with traditional composting, the present invention greatly shortens the fermentation time and saves costs, providing an innovative and efficient technical solution for the resource utilization of garden waste, and having significant ecological and economic benefits. Specific implementation method

[0029] In order to make the technical problems, technical solutions, and beneficial effects to be solved by the present invention clearer and more understandable, the following further elaborates on the present invention in combination with embodiments.

[0030] Example 1

[0031] In this example, the water content of garden waste is 15%, and the method for preparing organic fertilizer from garden waste includes the following steps:

[0032] 1. Pretreatment: Place 10 kg of garden waste in a microwave reactor. The microwave power applied by the microwave reactor to the garden waste per unit mass is 100 W / kg, and react for 1 minute. This process removes a large amount of lignin and retains cellulose.

[0033] 2. Enzymatic hydrolysis: Dry the residue after pretreatment in step 1), add cellulase, and the addition amount of the enzyme is 1 unit per gram of residue. Perform enzymatic hydrolysis treatment for 48 hours to obtain an enzyme solution as the main nutrient solution required for the growth of microorganisms.

[0034] 3. Detoxification: Add 0.1% (w / v) activated carbon as an adsorbent to the enzyme solution while shaking to remove toxic substances such as aldehydes, acids, and phenols that inhibit fermentation.

[0035] 4. Composting fermentation: After sterilizing the solution obtained in step 3), inoculate Bacillus subtilis. The inoculation amount of Bacillus subtilis is 1 mL per kilogram of garden waste. Incubate for 1 hour, and then inoculate it into the garden waste for composting. The environmental temperature for composting fermentation is controlled at 25 °C, and the composting fermentation time is 24 hours.

[0036] Experimental results: At the initial stage of fermentation, the matrix particles are larger, the texture is viscous, the color is lighter, tending to the color of garden waste, and there is a smell release; after fermentation for a period of time, the particle size of the matrix becomes smaller, the texture is loose, the color gradually deepens, and finally it becomes dark gray, accompanied by a soil smell, indicating that the compost has made a certain degree of decomposition progress. However, compared with other examples, the nutrient content improvement and material conversion speed are slower.

[0037] Example 2

[0038] In this example, the water content of the garden waste is 30%. The method for preparing organic fertilizer from garden waste includes the following steps:

[0039] 1. Pretreatment: Put 15 kg of garden waste into a microwave reactor, set the microwave power to 500 W / kg, and react for 60 minutes to effectively remove lignin and retain cellulose.

[0040] 2. Enzymatic hydrolysis: Dry the residue after pretreatment in step 1), add cellulase, and the addition amount of the enzyme is 25 units per gram of residue. Perform enzymatic hydrolysis for 48 hours to obtain an enzyme solution.

[0041] 3. Detoxification: Add 2.5% (w / v) activated carbon to the enzyme solution while shaking to remove toxic substances.

[0042] 4. Composting fermentation: Inoculate the sterilized enzyme solution with Bacillus subtilis, and the inoculation amount is 50 mL per kilogram of garden waste. After incubating for 12 hours, inoculate it into the garden waste. The environmental temperature for composting fermentation is maintained at 32 °C, and ferment for 120 hours.

[0043] Experimental results: The fermentation process is relatively smooth. After 9 days, the particle size of the matrix particles becomes significantly smaller, the texture is loose, the color is significantly deepened, showing dark gray, accompanied by a soil smell. The contents of total nitrogen, total phosphorus, and total potassium increase with the increase of fermentation time. The total nutrient (N + P2O5 + K2O) content reaches a certain level, the organic matter content decreases, and the C / N approaches the ideal composting range, indicating that the composting effect is good and a better resource utilization effect is achieved.

[0044] Example 3

[0045] In this embodiment, the water content of the garden waste is 50%, and the method for preparing organic fertilizer from garden waste includes the following steps:

[0046] 1. Pretreatment: Place 20 kg of garden waste in a microwave reactor with a microwave power of 1000 W / kg and react for 120 minutes to remove a large amount of lignin and retain cellulose.

[0047] 2. Enzymatic hydrolysis: Dry the residue after the pretreatment in step 1), add cellulase with an addition amount of 50 units per gram of residue, and perform enzymatic hydrolysis for 48 hours to obtain an enzyme solution.

[0048] 3. Detoxification: Add 5% (w / v) activated carbon to the enzyme solution, add it slowly and shake to eliminate the components inhibiting fermentation.

[0049] 4. Composting fermentation: Inoculate Bacillus subtilis into the sterilized enzyme solution with an inoculation amount of 100 mL per kg of garden waste, cultivate for 24 hours, then inoculate it into the garden waste, and control the environmental temperature of the composting fermentation at 40 °C and continue composting for 240 hours.

[0050] Experimental results: The phenomena in the initial stage of fermentation are similar to those of other embodiments. As time goes by, the changes in the composting materials are significant. Finally, it reaches a state of dark gray, loose texture, and strong soil smell. The contents of various nutrient elements increase significantly, the total nutrient content is high, the organic matter is decomposed sufficiently, and the C / N meets the maturity standard, fully verifying the feasibility of this process in achieving efficient composting and preparing high-quality organic fertilizer when treating garden waste with high water content.

[0051] Example 4

[0052] In this embodiment, the water content of the garden waste is 25%, and the method for preparing organic fertilizer from garden waste includes the following steps:

[0053] 1. Pretreatment: Place 12 kg of garden waste in a microwave reactor with a microwave power of 300 W / kg and react for 30 minutes to remove lignin and retain cellulose.

[0054] 2. Enzymatic hydrolysis: Dry the residue after the pretreatment in step 1), add cellulase with an addition amount of 30 units per gram of residue, and perform enzymatic hydrolysis for 48 hours to obtain an enzyme solution.

[0055] 3. Detoxification: Add 1.5% (w / v) activated carbon to the enzyme solution to remove toxic substances.

[0056] 4. Composting fermentation: Inoculate the sterilized enzyme solution with Bacillus subtilis with an inoculation amount of 30 mL per kg of garden waste, cultivate for 8 hours, then inoculate it into the garden waste, and keep the environmental temperature of the composting fermentation at 30 °C and compost for 72 hours.

[0057] Experimental results: The composting process is stable. During the middle stage, significant changes occur in the matrix particles, texture, and color. The total nutrient content increases steadily, the nitrogen element is transformed reasonably, the C / N is gradually optimized, and the effective conversion of garden waste into organic fertilizer is achieved in a relatively short 72 hours, combining both efficiency and quality, reflecting the adaptability and advantages of this process under different parameter combinations.

Claims

1. A method for preparing organic fertilizer using garden waste, characterized in that, It includes the following steps: 1) Pretreatment: Place the garden waste in a microwave reactor for reaction to remove a large amount of lignin and retain cellulose; 2) Enzymatic hydrolysis: Dry the residue after the pretreatment in step 1), conduct enzymatic hydrolysis treatment to obtain an enzyme solution as the main nutrient solution required for microbial growth; 3) Detoxification: Add activated carbon as an adsorbent to the enzyme solution obtained in step 2), add it while shaking to remove the toxic substances inhibiting fermentation; 4) Composting fermentation: After sterilizing the solution obtained in step 3), inoculate Bacillus subtilis for cultivation, and then inoculate it into the garden waste for composting fermentation.

2. The method for preparing organic fertilizer using garden waste as claimed in claim 1, wherein: The water content of the garden waste is 15% - 50%.

3. The method for preparing organic fertilizer using garden waste as claimed in claim 1, wherein: In step 1), the microwave power applied to the garden waste per unit mass by the microwave reactor is 100 - 1000 watts / kg, and the reaction time of the microwave reactor is 1 - 120 minutes.

4. The method for preparing organic fertilizer using garden waste as claimed in claim 1, wherein: In step 2), the enzyme used for enzymatic hydrolysis treatment is cellulase, and the addition amount of cellulase is 1 - 50 units per gram of residue.

5. The method for preparing organic fertilizer using garden waste as claimed in claim 1, wherein: In step 2), the time of enzymatic hydrolysis treatment is 36 - 72 hours.

6. The method for preparing organic fertilizer using garden waste as claimed in claim 1, characterized in that: In step 3), calculated by mass - volume ratio, the addition amount of activated carbon is 0.1% - 5% of the enzyme solution.

7. A method for preparing organic fertilizer using garden waste as claimed in claim 1, characterized in that: In step 4), the inoculation amount of the Bacillus subtilis is 1 - 100 mL per kilogram of garden waste.

8. The method for preparing organic fertilizer using garden waste as claimed in claim 1, characterized in that: In step 4), the cultivation time of inoculating Bacillus subtilis is 1 - 24 hours.

9. The method for preparing organic fertilizer by using garden waste as claimed in claim 1, wherein: In step 4), the temperature of composting fermentation is 25 - 40 °C.

10. A method for preparing organic fertilizer using garden waste as claimed in claim 1, characterized in that: In step 4), the time of composting fermentation is 24 - 240 hours.