Method for household preparation of solid-state excitant slow-release fertilizer from kitchen garbage

Abstract

The invention discloses a method for household preparation of a solid-state incentive element slow-release fertilizer from kitchen garbage, and belongs to the technical field of organic solid waste resourceful treatment. According to the invention, the kitchen garbage is crushed and pulpified; then decomposing organic matters in the kitchen garbage into plant growth excitant substances such as monosaccharide, volatile fatty acid and the like by utilizing composite biological hydrolase; then a chemical catalyst is added to promote generation of humic acid, rapidly available phosphorus, rapidly available potassium and other plant growth excitants, and meanwhile, residual solid lignin and cellulose form a porous hydrothermal carbon material. And finally, performing dehydration and drying treatment to promote the precipitation of an excitant substance, and stably adsorbing the excitant substance on the hydrothermal carbon material to form the solid-state excitant slow-release fertilizer. The method disclosed by the invention can be carried out in a normal-pressure container, does not add corrosive, toxic or odorous substances, and is completely suitable for being carried out in a family environment. The plant fertilizer efficiency of the prepared solid-state incentive element slow-release fertilizer is equivalent to that of a chemical compound fertilizer, preparation can be completed within 8 hours, the solid-state incentive element slow-release fertilizer is completely different from a traditional biological composting process and is also different from a preparation process of charcoal or hydrothermal fertilizer, and the solid-state incentive element slow-release fertilizer has obvious creative significance.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing solid-state stimulant slow-release fertilizer from kitchen waste at home, and belongs to the technical field of organic solid waste resource treatment. BACKGROUND

[0002] The implementation of garbage classification system means that the "convenient" mode of discarding on the ground in the past will disappear. However, the existing centralized treatment mode generally faces problems such as high investment cost, long collection and transportation chain, low added value of treatment products, and insufficient enthusiasm of residents in participating in the system. Under this background, the development of household-applicable in-situ treatment technology for wet garbage has great potential. If wet garbage can be directly converted by household appliances in residents' homes, not only the annoyance of household wet garbage treatment can be eliminated, but also fertilizer for gardening can be obtained, thereby greatly stimulating the enthusiasm of residents in participating in garbage resourceization. More importantly, this can omit the complex links of subsequent collection, classification, transportation, etc., and reduce the burden of urban garbage classification and resourceization disposal system from the source. E-commerce platform data shows that the sales volume of vegetable seeds reached 50 million in 2023, and the daily transaction volume of intelligent planting boxes exceeded 2 million yuan. In 2024, the online sales of household gardening related products exceeded 800 million yuan, the daily search volume of intelligent planting equipment exceeded 80,000 times, and the sales volume of blueberry potted plants and other specialty crops increased by 300% year-on-year. It is estimated that the market size will exceed 12 billion yuan in 2025, and the proportion of intelligent equipment will reach 40%. In 2023, the market size of gardening fertilizer reached 132.48 billion yuan (only 90.2 billion yuan in 2016), with a compound annual growth rate of 6.2%. With the expansion of the household gardening market, many families who love gardening tend to choose green and environmentally friendly and low-cost self-made organic fertilizer, and the market growth rate of household composting barrels is 120% per year. However, self-made fertilizer has the problems of complicated operation, heavy odor, and unstable fertilizer effect.

[0003] Biological composting is the most common way of kitchen waste resourceization, which can convert organic matter into available organic fertilizer within 30-60 days. However, its long cycle (more than one month) cannot meet the demand of households for convenience and speed. Technologies such as pyrolysis can shorten the treatment time and produce biochar fertilizer, but they require high-temperature conditions (> 400°C) or the use of strong acids / strong bases for catalysis, which have problems such as high energy consumption, great safety hazards, and dangerous operation, and are completely unsuitable for household environments. Therefore, it is urgent to break through the existing time and space limitations and develop new technologies for making fertilizer from kitchen waste and other biomass at low temperature (< 100°C), short time (≤ 8 hours), safety, and high product added value. SUMMARY

[0004]

Technical problem

[0005] [Technical Solution] The first aspect of this invention is to provide a method for preparing solid stimulant slow-release fertilizer from kitchen waste at home, the method comprising the following steps: S1. Mix and crush the kitchen waste to obtain a slurry with a moisture content of 30 wt% to 90 wt%. S2. Add compound biological hydrolytic enzyme to the slurry of S1 for enzymatic hydrolysis to decompose kitchen waste into plant growth stimulants and their precursors, including various small molecule proteins, polypeptides, amino acids, small molecule sugars and fatty acids. S3. A catalyst is added to the enzymatic hydrolysis product of the slurry in S2 to carry out a catalytic reaction, further catalyzing the precursor substances formed in S2 to generate plant growth stimulants. The remaining kitchen waste solids are hydrothermal charcoal materials. The plant growth stimulants include humic acid, available phosphorus, and available potassium. The hydrothermal charcoal materials are porous and adsorbent carbonized cellulose and lignin. S4. The catalytic mixture of S3 is dehydrated until the moisture content of the material is reduced to 20 wt%~30 wt%. While the moisture is lost, the plant growth stimulants in S2 and S3 are continuously released and adsorbed onto the hydrothermal carbon material. S5. Heat up and dry the material from S4 to stabilize the plant growth stimulants on the hydrothermal carbon material. When the moisture content of the material is below 2 wt%, stop heating and continue stirring to obtain powdered slow-release fertilizer. The method takes ≤8.0 h, and steps S1-S5 are performed under normal pressure. Furthermore, the kitchen waste is a solid or liquid rich in organic matter and without significant biological toxicity.

[0006] Furthermore, the kitchen waste includes vegetables, starch, fruits, meat, and / or cooking oil.

[0007] Furthermore, the pH value of the kitchen waste is between 5 and 7, which is conducive to the generation of nutrients.

[0008] Furthermore, in S1, the particle size of the pulverized solid is less than 10 mm, which is beneficial for enzymatic hydrolysis and catalytic reactions.

[0009] Furthermore, in S2, the temperature of the enzymatic hydrolysis reaction is 40-80℃; the temperature of the enzymatic hydrolysis reaction is the optimal reaction temperature of the complex hydrolase.

[0010] In some embodiments of the present invention, the complex hydrolase is a lipase and a saccharifying enzyme.

[0011] The lipase can hydrolyze the ester bond in the oil and fat molecules to decompose them into smaller fatty acids and glycerol; the saccharifying enzyme, also known as glucoamylase, can hydrolyze the alpha-1,4 glycosidic bond from the non-reducing end of the carbon chain of starch and the like to cut off glucose units to generate glucose.

[0012] In some embodiments of the present application, the enzyme activity of the lipase is 10000-100000 u / L, and the enzyme activity of the saccharifying enzyme is 80000-140000 u / L.

[0013] In some embodiments of the present application, the dosages of the lipase and the saccharifying enzyme are 10-80 ml / kg of kitchen garbage, respectively.

[0014] When the dosage of the complex hydrolytic enzyme is higher than 80 ml / kg of kitchen garbage, the degradation effect will not be improved with the increase of the dosage, but the operating cost will be increased.

[0015] Alternatively, the complex hydrolytic enzyme further contains a protease, and the dosage is 10-80 ml / kg of kitchen garbage.

[0016] In some embodiments of the present application, the enzyme activity of the protease is 10000-100000 u / L.

[0017] Further, in S2, the time of the enzymatic hydrolysis reaction is ≥2 h, and the stirring rate is ≥5 rpm.

[0018] Preferably, in S2, the time of the enzymatic hydrolysis reaction is 2-10 h, and the stirring rate is 5-10 rpm.

[0019] In some embodiments of the present application, in S3, the catalyst is selected from manganese sulfate and / or tetrabutylammonium bromide, which has high safety and is suitable for use in a family environment and will not produce any toxic gas during use.

[0020] In some embodiments of the present application, in S3, the addition amount of the catalyst is 5-50 g / kg of kitchen garbage.

[0021] Further, in S3, the reaction conditions of the catalysis are 80-100℃, the stirring rate is ≥5 rpm, and the reaction time is ≥1 h.

[0022] Preferably, in S3, the reaction conditions of the catalysis are 80-100℃, the stirring rate is 5-10 rpm, and the reaction time is 1-5 h.

[0023] In some embodiments of the present application, in S4, the reaction temperature of the dehydration is ≥80℃, the stirring rate is ≥10.0 rpm, and the reaction time is ≥1.0 h. The reaction temperature is above 80℃, so that the plant elicitor can be continuously precipitated and is not easily decomposed.

[0024] Further, in S4, the reaction temperature of the dehydration is 80-100℃, the stirring rate is 10-40 rpm, and the reaction time is 1-5 h.

[0025] In some embodiments of the present application, in S5, the temperature is raised to 100-150℃, and the stirring rate is 5-20 rpm.

[0026] In some embodiments of the present application, the particle size of the powdery slow-release fertilizer is less than 2 mm.

[0027] In the technical solution of the present application, the goal is to obtain high-value organic fertilizer, and other by-products are not excessively pursued, and the evaluation criteria for the reaction effect are the yield of plant growth stimulants and the effect of organic fertilizer on promoting plant growth.

[0028] Unlike the traditional kitchen waste treatment process in which triglycerides are only hydrolyzed into glycerol and fatty acids that can be dissolved in water, and the oil is removed by water phase separation; the technical solution of the present application gradually and completely transforms kitchen waste into solid plant growth stimulant slow-release fertilizer through biological enzyme hydrolysis, thermochemical catalytic reaction and dehydration, and no harmful substances are discharged, and the implementation process is efficient, safe and non-toxic.

[0029] The second aspect of the present application is to provide a solid-state growth stimulant slow-release fertilizer prepared according to the method.

[0030] The third aspect of the present application is to provide the use of the method or the solid-state growth stimulant slow-release fertilizer in the planting of agricultural and forestry crops.

[0031] Advantages (1) Significant economic benefits. First, compared with traditional biological composting, the treatment process is shortened from 30-90 days of traditional technology to within a few hours, which has beneficial effects in many aspects such as site occupation, labor maintenance cost and energy consumption. Second, compared with existing new fertilizer preparation processes such as biochar and hydrothermal carbon preparation, the heating temperature is reduced to 100℃ or less from 200-800℃ of these processes, which can be carried out at normal pressure, and the investment and operating costs are greatly reduced. In addition, the solid-state growth stimulant slow-release fertilizer produced by the present application has much higher added value, and its fertility is comparable to chemical compound fertilizer, with Kjeldahl nitrogen (TKN) content of 25.1-25.4 g / kg, total nitrogen (TDN) content of 9.8-10.5 g / kg, ammonia nitrogen (NH4 + -N) content of 2 g / kg, total phosphorus (TP) content of 8.1 g / kg, and orthophosphate (PO4 3-The content of P reaches 5.4 g / kg, and the organic fertilizer has the effect of improving soil.

[0032] (2) Green and environmentally friendly. Firstly, compared with the traditional bio-composting technology, the present application converts part of the organic matter of kitchen waste, such as lignin and cellulose, into hydrothermal carbon, and immobilizes it in the soil as part of the solid stimulant slow-release fertilizer, which belongs to a kind of negative carbon technology. Secondly, compared with the preparation of biochar or hydrothermal carbon and other negative carbon technologies, the preparation process of the organic fertilizer of the present application has low energy consumption and does not need to use high temperature conditions (< 150 DEG C), achieving the effect of energy saving and emission reduction. In addition, the preparation of kitchen waste into high value-added organic fertilizer is itself a pollution treatment and disposal measure, and has significant environmental benefits.

[0033] (3) Outstanding social benefits. Firstly, the method provided by the present application is suitable for in-situ treatment of kitchen waste generated by residents, saving a series of processes such as collection, classification, transportation, sorting, pretreatment, treatment, residue disposal and wastewater treatment in the existing garbage disposal mode, greatly saving resources. Secondly, residents convert kitchen waste into fertilizer that can be used for garden fertilization, and the enthusiasm of participation is greatly aroused. Therefore, the present application also shows very good social benefits.

[0034] (4) The present application breaks and slurries the kitchen waste, then decomposes polysaccharides and oils and other organic matters in the kitchen waste into monosaccharides and volatile fatty acid and other plant growth stimulating substances by using composite biological hydrolytic enzyme under normal or medium temperature, then adds a chemical catalyst and heats to medium-high temperature to promote the generation of humic acid, available phosphorus, available potassium and other plant growth stimulating substances, at the same time, the residual solid lignin and cellulose will be melted due to the melting of protein, polysaccharide and other components to form porous hydrothermal carbon material, then the stimulating substance is precipitated and adsorbed on the hydrothermal carbon material by medium-high temperature dehydration treatment, finally, the temperature is increased to 100-150 DEG C to stabilize and fix the stimulating substance on the hydrothermal carbon to form a solid stimulating substance slow-release fertilizer. The most core advantage of the present application lies in the adaptation to "family applicability", which is essentially different from the technology depending on high temperature and high pressure, strong acid and strong base. The method provided by the present application operates under relatively low reaction temperature and normal pressure, and does not use any dangerous reagent in the whole process, so that it can be used for family operation. In the production of products, the rate limitation of natural metabolism of microorganisms is broken, the core technology can efficiently catalyze the directional conversion of organic matter in kitchen waste into plant stimulating substance in a very short time, and the product has the advantages of promoting growth and improving soil. In terms of product added value, the chemical stabilization of the product is realized simultaneously in the treatment process, and finally a high added value slow-release organic fertilizer with stable form and slow and long lasting nutrient release is obtained, which not only avoids the risk of nutrient loss and seedling burning, but also is more suitable for the habit of small amount and multiple fertilization of family potting and garden. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 Conversion of nitrogen in Example 3; Figure 2 Conversion of nutrients in Example 4; Figure 3 Seed germination index in Example 5; Figure 4 Plant height, tillering number, root length and fresh weight of green vegetables in Example 6; Figure 5 COD, polysaccharides, protein and oil measured after enzymolysis of kitchen waste by different enzyme combinations in Comparative Example 1. DETAILED DESCRIPTION

[0036] The present application will be further described in detail below in combination with specific examples, but the present application is not limited to these examples.

[0037] The technical solutions of the present application will be described clearly and completely below in combination with the drawings and the embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application, which do not limit the claims of the present application. The experimental methods described in the following embodiments are all conventional methods, unless otherwise specified. The reagents and materials described in the following embodiments are all commercially available, unless otherwise specified.

[0038] In the following embodiments, (1) The method for determining the nutrient elements: The nutrient element indicators include Kjeldahl nitrogen (TKN), ammonia nitrogen (NH4 + -N), total nitrogen (TN), total phosphorus (TP), and phosphate (PO4 3- -P) content, which are used to evaluate the richness of plant nutrients in the plant stimulants. The determination method adopts the method described in the industry standard “Organic Fertilizer (NY525-2012)”. Kjeldahl nitrogen is determined by Kjeldahl nitrogen determination method, and total nitrogen, ammonia nitrogen, total phosphorus, and phosphate are determined by spectrophotometry.

[0039] (2) The method for determining the seed germination index: The seed germination index (GI) is determined by the method described in the industry standard “Organic Fertilizer (NY525-2012)”. 10.00 g of the sample (fresh sample) is placed in a 250 ml conical flask, and the corresponding amount of water is added according to the solid-liquid ratio (mass / volume) 1:10 after the water content of the sample is converted. The sample is oscillated and extracted for 1 h at 25℃, and then it is taken out and allowed to stand for 0.5 h. The supernatant is centrifuged, and the filtered extraction solution is collected and shaken for analysis. One or two qualitative filter papers are placed in a 9 cm culture dish, and 10 full and uniform cucumber seeds are evenly placed on each filter paper. 10 mL of the test sample extraction solution is added, and the culture dish cover is covered. The culture dish is cultured in a 25±2℃ incubator in the dark for 48 h. The number of germinated seeds is counted, and the length of the main root is measured with a vernier caliper.

[0040] The composition of the kitchen garbage used in the embodiments is shown in the following table.

[0041] Table 1 Composition of simulated kitchen garbage The COD is determined by potassium dichromate oxidation method Reference is made to the national environmental protection standard HJ615-2011.

[0042] (4) The polysaccharide is determined by phenol-sulfuric acid method Take the standard dextran, dilute 8 concentrations respectively, take 0 as blank, and supplement with distilled water. Then add 1.2 ml of 6% phenol solution and 6.5 ml of concentrated sulfuric acid, shake well and stand for 30 minutes. Measure the absorbance of each point at 490 nm wavelength of spectrophotometer, which can be repeated three times to obtain the average value. Take the concentration of polysaccharide as the abscissa and the absorbance value as the ordinate to obtain the standard curve and calculate the regression equation.

[0043] Take the sample solution to be measured, take 1.0 ml into a colorimetric tube, add 1.2 ml of 6% phenol solution and 6.5 ml of concentrated sulfuric acid, shake well and stand for 30 min, and cool by cold water.

[0044] (5) The oil and fat was determined by Soxhlet extraction method.

[0045] Refer to the national standard GB 5009.6-2016.

[0046] Example 1: Simulation of the conversion of nutritional elements in kitchen garbage (1) Conversion of kitchen garbage: S1, to simulate the actual conditions, self-configured simulated kitchen garbage was used for experiment. The simulated kitchen garbage in Table 1 was mixed and crushed; S2, 20 ml / kg of lipase (100000 u / L) and 20 ml / kg of saccharifying enzyme (140000 u / L) were added to the slurry obtained in S1, after the addition was completed, the temperature was raised to 60±2℃, and stirred at 5 rpm for 5 h; S3, after the treatment of the complex hydrolytic enzyme was completed, 20 g / kg of catalytic reagent was continuously added, which could be manganese sulfate, after the addition was completed, the temperature was raised to 100℃, and stirred at 5 rpm for 1 h.

[0047] S4, the slurry mixture of S3 was maintained at the same temperature, and dehydration treatment was carried out, and the stirring treatment was carried out at 30 rpm for 2 h.

[0048] S5, the material in S4 was heated to 130℃, and dehydration treatment was continued, and the stirring was continued at 10 rpm.

[0049] S6, when the moisture content of the material was less than 2%, the heating was stopped, and after a period of stirring, the material was discharged, and a powder-like solid stimulant slow-release fertilizer was obtained.

[0050] (2) Nutritional element determination: The sample in S6 was dried in a freeze dryer and then ground in a mortar to a particle size of less than 2 mm. Part of the powdered solid sample was used to determine Kjeldahl nitrogen. Using a 1 M potassium chloride (KCl) solution, the weighed sample was added with the KCl solution at a solid-liquid ratio of 1:10. The tightly capped (to prevent ammonia loss by volatilization) was placed on a horizontal shaker and shaken at room temperature (25±2°C) for 1 h extraction at 200 rpm, and then centrifuged at high speed (8000 rpm, 10 min) at room temperature. After centrifugation, the supernatant was filtered through a 0.45 μm filter membrane to remove finer colloidal particles. The filtered solution was used to determine total nitrogen, total phosphorus, orthophosphate and ammonia nitrogen, and the results are shown in Table 2.

[0051] Table 2 Nutrients and their contents The results show that the kitchen waste-based solid plant stimulant contains high levels of ammonia nitrogen, total nitrogen, Kjeldahl nitrogen, orthophosphate and total phosphorus.

[0052] Example 2: Simulation of the transformation of nutrients in kitchen waste The experimental steps and conditions are basically the same as in Example 1, except that the catalyst manganese sulfate is replaced by tetrabutylammonium bromide. Similarly, the nitrogen, total phosphorus, orthophosphate and ammonia nitrogen in the prepared solid stimulant slow-release fertilizer were determined, and the results show that the kitchen waste-based solid plant stimulant contains high levels of ammonia nitrogen, total nitrogen, Kjeldahl nitrogen, orthophosphate and total phosphorus, similar to the results of Example 1.

[0053] Table 3 Nutrients and their contents Example 3: Simulation of the transformation of nitrogen in kitchen waste The experimental steps and conditions are basically the same as in Example 1, except that the initial pH of the added kitchen waste is different, with an initial pH of 5-7. Part of the sample was taken at 0 h, 5 h and 8 h to determine TKN, TDN, NH4 + -N, polypeptides, proteins.

[0054] The results are shown in Table 2, and the results show that the initial pH of the kitchen waste has a significant effect on the transformation of nutrients. Figure 1

[0055] Example 4: Effect of different initial pH on nutrients in kitchen waste This example verifies the effect of the initial pH of kitchen waste on the transformation of nutrients.

[0056] ​The experimental steps and conditions are basically the same as those in Example 1, the difference is that the initial pH of the kitchen waste added is different, and the initial pH is set to 5, 7 and 9 respectively. After completion, part of the sample is taken to determine the nutrient elements.

[0057] The results are shown in Table 3. Figure 2 It is shown that under acidic conditions, the contents of ammonia nitrogen, total nitrogen and Kjeldahl nitrogen are higher than those under neutral and alkaline conditions. Under alkaline conditions, NH4 + -N only 40% under acidic conditions; orthophosphate and total phosphorus are less affected by pH. Generally, the initial pH of kitchen waste is acidic, which can produce more plant hormones.

[0058] Example 5: Seed germination index experiment of solid-state hormone slow-release fertilizer In this example, real kitchen waste is collected and solid-state hormone slow-release fertilizer is prepared according to the method of Example 1. The composition of real kitchen waste is shown in Table 4. In this example, a kitchen waste solid-state hormone slow-release fertilizer treated only with enzymes is also set as a control group to verify the effects of different dilutions of the sample prepared in Example 1, real kitchen waste solid-state hormone slow-release fertilizer and kitchen waste solid-state hormone slow-release fertilizer treated only with enzymes on seed germination, in order to find the best fertilizer dosage. Among them, the kitchen waste solid-state hormone slow-release fertilizer treated only with enzymes refers to only including S1 and S2 steps in the method provided in Example 1.

[0059] Table 4 Composition of real kitchen waste (1) Comparison of components of kitchen waste-based and real kitchen waste-based plant hormone solid slow-release fertilizer The various indicators in the kitchen waste-based plant hormone prepared in Example 1 and the real kitchen waste-based fertilizer prepared by the same method in Example 1 are tested, and the results are recorded in Table 5.

[0060] The results show that the real kitchen waste can realize comprehensive and efficient conversion and enrichment of nutrient components by the method provided in the application, and the conversion of kitchen waste to organic fertilizer can be completed in a short time.

[0061] Table 5 Comparison of components of kitchen waste-based and real kitchen waste-based solid-state hormone slow-release fertilizer (2) Seed germination index of kitchen waste-based and real kitchen waste-based plant hormone solid slow-release fertilizer Take 10 g of the sample dried by the freeze dryer in Example 1, put it into a 250 mL conical flask, add 100 mL of distilled water, plug the flask, put it into a constant temperature shaker at 30℃ for 1 h. After the shaking, first stand for 0.5 h, then filter with a filter device, collect the supernatant extract for standby use. Take 3 petri dishes for each sample, put 1 qualitative filter paper on each petri dish. Then add 10 full cucumber seeds and 10 mL of the supernatant extract. Cover the petri dish, put it into a constant temperature incubator at 25℃ for 48 h. Count the number of germinated seeds manually and measure the length of the main root with a tape measure. The blank test uses distilled water as the control.

[0062] The results are shown in Table 1. Figure 3 The results are shown in Table 1.

[0063] Example 6: Potting growth experiment for testing the fertilizer effect of solid-state stimulating nutrient slow-release fertilizer (taking Chinese cabbage as an example) The experimental soil is slightly acidic with a pH value of 5.6-5.7 and a sandy yellow color, and the soil nutrient content is low. Chinese cabbage seedlings are planted in flowerpots with a diameter of 195 mm and a depth of 140 mm, which can accommodate up to 1330 cm 3 . 2000 g of soil is poured into each seedling pot, 4 g of commercially available chemical compound fertilizer (Stanley) is added to one group, and 4 g, 20 g, 40 g and 80 g of solid-state stimulating nutrient slow-release fertilizer produced by the present application are added to the other four groups, respectively, and one group is not added with fertilizer as a control group. After the soil and fertilizer are mixed evenly, water is poured to saturation. The Chinese cabbage seedlings purchased in advance are evenly planted in the pots. Each pot has 4 seedlings with similar growth. 100 mL of water is sprayed into the soil at a constant amount and time every day. The plant height and tiller number of Chinese cabbage are measured every 4 days. After 28 days, the mature Chinese cabbage is harvested, and the root length and fresh weight are measured. Three parallel samples are set for each group of experiments, and the results are shown in Table 2. Figure 4

[0064] The results are shown in Table 1. Figure 4 ​The results show that during the first 10 days of the experiment, the leafy greens grew stably with no significant difference in plant height. From day 10 to 20, the growth rate of the leafy greens in the organic fertilizer group was significantly faster than that in the compound fertilizer group and the control group. However, after 10 days, the growth rate of the leafy greens in the organic fertilizer group slowed down. Similar conclusions were drawn regarding tiller number and plant height; during the first 10 days, there was no significant difference in tiller number. From day 15 to 25, the tiller number growth rate in the organic fertilizer group (1.4 cm / d) was faster than that in the compound fertilizer group (0.9 cm / d) and the control group (0.05 cm / d). The root length and fresh weight of the leafy greens are shown in the figure. At day 28, the leafy greens in the low-concentration organic fertilizer group showed better results than those in the compound fertilizer group.

[0065] Comparative Example 1: This embodiment aims to verify the effect of complex hydrolases on the conversion of nutrient elements. The following groups were set up: blank group, amylase group, protease group, lipase group, amylase and lipase group, amylase and protease group, protease and lipase group, and three-enzyme group (protease + amylase + lipase).

[0066] The experimental procedures and conditions were basically the same as in Example 1, except for stage S2. Depending on the group settings, 20 ml / kg of lipase (100,000 u / L), 20 ml / kg of saccharifying enzyme (140,000 u / L), and / or 20 ml / kg of protease (100,000 u / L) were added to the kitchen waste. Every 2 hours, a portion of the sample was taken to determine COD, polysaccharides, ammonia nitrogen, and oil content.

[0067] The results showed that, Figure 5 As shown, the protein content of the three-enzyme group (protease + amylase + lipase) decreased to 0.95 g / L, which was lower than that of the two-enzyme group and the single-enzyme group, indicating that the protease and other enzymes worked synergistically to enhance the protein hydrolysis effect. Although the protein hydrolysis effect of the two-enzyme group (protease and amylase) was not as good as that of the two-enzyme group (protease and amylase) and the three-enzyme group, it was still significantly better than that of the single protease group.

[0068] The SCOD of the three-enzyme group increased from 21 g / L to 32.37 g / L, showing the largest increase and demonstrating its ability to efficiently decompose complex organic matter into soluble substances. Among them, the results of the two-enzyme group (amylase and lipase) were similar to those of the three-enzyme group, both increasing to 32 g / L.

[0069] In the polysaccharide detection results, the three-enzyme group performed slightly worse than the two-enzyme group (amylase and lipase), indicating that amylase and lipase synergistically promoted the release of polysaccharides.

[0070] The lipid content in the three-enzyme group decreased from 2.8 g / L to 1.52 g / L, which was better than that in the single-lipase group. The results of the two-enzyme group (amylase and lipase) were comparable to those of the three-enzyme group, both decreasing to 1.5 g / L.

[0071] Comprehensive analysis results, three enzyme groups have certain advantages in COD, protein and oil three indicators, but overall, double enzyme group (amylase and lipase) and three enzyme groups are comparable, and the polysaccharide content is better than that of three enzyme groups. In addition, the storage condition of the complex enzyme reagent containing protease is more demanding (-20℃), and the storage time is shorter, so the reagent formula of amylase + lipase is preferred.

[0072] The above only describes the embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent transformation or direct or indirect application in related technical fields using the content of the present application is also included in the patent protection scope of the present application.

Claims

1. A method for preparing solid stimulant slow-release fertilizer from kitchen waste at home, characterized in that, Includes the following steps: S1. Mix and crush the kitchen waste to obtain a slurry with a moisture content of 30 wt% to 90 wt%. S2. Add compound biological hydrolytic enzyme to the slurry of S1 for enzymatic hydrolysis to decompose kitchen waste into plant growth stimulants and their precursors, including various small molecule proteins, polypeptides, amino acids, small molecule sugars and fatty acids. S3. A catalyst is added to the enzymatic hydrolysis product of the slurry in S2 to carry out a catalytic reaction, further catalyzing the precursor substances formed in S2 to generate plant growth stimulants. The remaining kitchen waste solids are hydrothermal charcoal materials. The plant growth stimulants include humic acid, available phosphorus, and available potassium. The hydrothermal charcoal materials are porous and adsorbent carbonized cellulose and lignin. S4. The catalytic mixture of S3 is dehydrated until the moisture content of the material is reduced to 20 wt%~30 wt%. While the moisture is lost, the plant growth stimulants in S2 and S3 are continuously released and adsorbed onto the hydrothermal carbon material. S5. Heat up and dry the material from S4 to stabilize the plant growth stimulants on the hydrothermal carbon material. When the moisture content of the material is below 2 wt%, stop heating and continue stirring to obtain powdered slow-release fertilizer. The method takes ≤8.0 h and is implemented under normal pressure in steps S1-S5.

2. The method according to claim 1, characterized in that, In S1, after the kitchen waste is crushed, the pH is 5-9 and the size is ≤10mm.

3. The method according to claim 1, characterized in that, In S2, the complex hydrolytic enzymes are lipase and saccharifying enzyme, and the dosage of the complex hydrolytic enzymes is 10-80 ml / kg of kitchen waste, with a reaction time ≥2.0 h.

4. The method according to claim 3, characterized in that, The lipase has an activity of 10,000-100,000 u / L, and the saccharifying enzyme has an activity of 80,000-140,000 u / L.

5. The method according to claim 1, characterized in that, In S3, the catalyst is manganese sulfate and / or tetrabutylammonium bromide, and the dosage is 5-50 g / kg of kitchen waste.

6. The method according to claim 1 or 5, characterized in that, The temperature is 80-100℃, the stirring speed is 5-10 rpm, and the reaction time is ≥1.0 h.

7. The method according to claim 1, characterized in that, In S4, the reaction temperature is ≥80℃, the stirring rate is ≥10.0rpm, and the reaction time is ≥1.0h.

8. The method according to claim 1, characterized in that, In S5, the temperature is raised to 110~150℃.

9. The solid stimulant slow-release fertilizer prepared by the method according to any one of claims 1 to 8.

10. The application of the method according to any one of claims 1 to 8 or the solid stimulant slow-release fertilizer according to claim 9 in the cultivation of agricultural and forestry crops.

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