Method for producing organic fertilizer by utilizing waste agriculture and forestry biomass and municipal sludge and application

Abstract

The invention relates to the technical field of organic fertilizer production, particularly discloses a method for producing an organic fertilizer by using waste agriculture and forestry biomass and municipal sludge and application, and aims to efficiently treat and utilize agricultural wastes and municipal sludge. The method comprises the following steps: by taking agricultural and forestry wastes such as corn straws, peanut shells and sawdust and municipal sludge as raw materials, firstly, crushing and screening biomass raw materials, and then, converting the biomass raw materials into a carbon-based material rich in organic matters by adopting a hydrothermal carbonization technology. And then, mixing the carbon-based material with the treated municipal sludge, inoculating flora for aerobic fermentation, and promoting the decomposition of organic matters under the action of microorganisms. Finally, the nutrient content and the soil improvement performance of the organic fertilizer are improved through activation and modification. According to the method, the environmental pollution risk caused by the waste agriculture and forestry biomass and the municipal sludge can be effectively reduced, the high-quality organic fertilizer which is rich in organic matter, balanced in nutrient and suitable for agricultural production can be produced, and remarkable environmental benefits and economic values are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of organic fertilizer production, and in particular to a method and application of producing organic fertilizer by utilizing waste agricultural and forestry biomass and municipal sludge. Background Art

[0002] With the continuous growth of the global population, the continuous expansion of agricultural production activities and the acceleration of urbanization, the amount of agricultural and forestry waste and municipal sludge is also increasing year by year. The disorderly treatment of these wastes not only wastes a large amount of organic resources, but also causes serious pollution to the environment. Therefore, how to effectively utilize agricultural and forestry waste and municipal sludge, reduce their negative impact on the environment, and realize the reuse of resources has become an urgent problem to be solved in the current environmental protection field.

[0003] Agricultural and forestry wastes mainly include corn stalks, peanut shells, sawdust, etc. These wastes are rich in organic matter and have high recycling value. However, due to the limitations of treatment and utilization technology, a large amount of agricultural and forestry wastes are directly incinerated or discarded, resulting in resource waste and environmental pollution. On the one hand, the burning of agricultural and forestry wastes will release a large amount of carbon dioxide and other harmful gases, aggravating air pollution and greenhouse effect; on the other hand, the random discarding of wastes will occupy a large amount of land resources and cause pollution to soil and water bodies. In recent years, various studies have been carried out on the treatment and utilization of agricultural and forestry wastes at home and abroad, among which the technologies represented by biomass energy development and organic fertilizer production have gradually matured. However, the existing biomass treatment technology still has problems such as low treatment efficiency, high cost, and complex process, which limits its promotion in large-scale applications.

[0004] In addition, municipal sludge is a solid waste generated during the treatment of urban sewage, which has the characteristics of high water content and rich organic matter content. Municipal sludge usually contains a certain amount of heavy metals, pathogenic microorganisms and harmful chemicals. If it is directly discharged or simply piled up without effective treatment, it will not only cause soil and water pollution, but also threaten human health and ecological environment safety. At present, the treatment of municipal sludge mainly includes landfill, incineration and composting. The landfill method is prone to secondary pollution and occupies a large amount of land resources; although the incineration method can reduce the amount of sludge, its high energy consumption and harmful gas emissions are its main disadvantages; the composting method can convert organic matter in sludge into organic fertilizer, but it requires a long treatment cycle and has limited effect on the removal of heavy metals. In addition, the odor and pathogenic bacteria problems in the composting process are also one of the challenges facing current technology.

[0005] Although the existing technology has made some progress in the treatment of agricultural and forestry waste and municipal sludge, there are still many shortcomings in practical application. For example, ①. Low treatment efficiency: The existing agricultural and forestry waste treatment technologies, such as incineration and composting, are usually inefficient due to the limitations of treatment equipment and processes, and cannot meet the needs of large-scale waste treatment; ②. Serious waste of resources: Many treatment methods cannot make full use of organic matter and other beneficial components in agricultural and forestry waste and municipal sludge, resulting in waste of resources. For example, although the incineration method has an obvious reduction effect, it will directly lose organic matter. ③. Prominent environmental pollution problems: In the existing treatment process, the incineration of agricultural and forestry waste will produce a large amount of carbon dioxide and harmful gases, and landfilling sludge may cause groundwater and soil pollution. In addition, the problem of heavy metal residues has not been effectively solved in municipal sludge treatment technology. ④. Complex process and high cost: The existing comprehensive treatment technology is often complex in process, with high equipment requirements and expensive operating costs, making it difficult to promote and use in practice.

[0006] In view of the deficiencies of the above-mentioned prior art, the present invention provides a method for producing organic fertilizer using waste agricultural and forestry biomass and municipal sludge. Through an innovative process combination, efficient treatment and resource utilization of waste agricultural and forestry biomass and municipal sludge are achieved, providing a new and effective solution to the problems of environmental pollution and resource waste, and has important application prospects and promotion value. Summary of the invention

[0007] The present invention aims to provide a method and application of producing organic fertilizer using waste agricultural and forestry biomass and municipal sludge, so as to obtain a high-quality organic fertilizer rich in organic matter, balanced in nutrients, and suitable for agricultural production, while effectively reducing the environmental pollution risk of waste agricultural and forestry biomass and municipal sludge.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] The method for producing organic fertilizer by using waste agricultural and forestry biomass and municipal sewage sludge comprises the following steps:

[0010] (A) crushing and screening agricultural and forestry waste to obtain biomass raw materials;

[0011] (B) subjecting the treated biomass raw material to hydrothermal carbonization to convert it into a carbon-based material rich in organic matter;

[0012] (C) High temperature and high pressure steam sterilization and heavy metal "adsorption-fixation-separation" treatment of municipal sewage sludge;

[0013] (D) mixing the carbon-based material with treated municipal sludge in a certain proportion, and then inoculating a bacterial community for aerobic fermentation, thereby promoting the decomposition of organic matter in the mixture under the action of the microbial community;

[0014] (E) activating and modifying the fermented mixture to obtain an organic fertilizer with balanced nutrients and soil improvement performance.

[0015] Furthermore, in the step (A), the particle size of the agricultural and forestry waste is controlled to be 0.5-2.5 mm, and the proportions of corn stalks, peanut shells and wood chips are 30-50%, 20-40% and 10-30% respectively.

[0016] Furthermore, in the step (B), the temperature of the hydrothermal carbonization treatment is controlled at 180-250° C., the pressure is controlled at 1.5-3.0 MPa, and the treatment time is 1-3 hours to ensure that the biomass raw material is fully carbonized.

[0017] Furthermore, in the step (C), the sterilization treatment of municipal sludge adopts a high temperature and high pressure steam method, the treatment temperature is 120-150°C, the pressure is 0.15-0.25MPa, and the treatment time is 30-60 minutes.

[0018] Furthermore, the heavy metal "adsorption-immobilization-separation" treatment in step (C) comprises the following steps:

[0019] (C1) adding adsorbent materials to municipal sludge to adsorb heavy metals in the sludge;

[0020] (C2) Immobilization of adsorbed heavy metals by chemical fixatives;

[0021] (C3) Separating the fixed heavy metal particles by gravity separation or centrifugation.

[0022] Furthermore, in the step (D), the mixing ratio of the carbon-based material to the municipal sludge is 1:2 to 1:5.

[0023] Furthermore, in the step (D), the bacterial community includes thermophilic cellulose decomposing bacteria, lactic acid bacteria, yeast and nitrifying bacteria.

[0024] Furthermore, in the step (D), the aerobic fermentation process is carried out at a temperature of 50-65° C. for 15-25 days, and the compost is turned regularly during the fermentation to ensure sufficient oxygen supply.

[0025] Furthermore, in the step (E), the activation modification treatment includes adding humic acid, amino acid and seaweed extract.

[0026] Furthermore, the organic fertilizer is suitable for planting a variety of crops, including cereals, vegetables and fruit trees.

[0027] Compared with the prior art, the beneficial effects of the present invention are mainly as follows:

[0028] (1) The present invention realizes the resource recycling of waste agricultural and forestry biomass and municipal sludge by innovatively combining the two wastes. Agricultural and forestry wastes are converted into carbon-based materials rich in organic matter by crushing, screening and hydrothermal carbonization, thereby retaining the organic matter in the raw materials to the maximum extent. At the same time, municipal sludge is sterilized by high-temperature and high-pressure steam and treated by "adsorption-fixation-separation" of heavy metals, which effectively removes harmful components in the sludge, making it suitable as a raw material for organic fertilizer, thereby achieving the purpose of reducing environmental pollution and recycling resources.

[0029] (2) The present invention adopts a treatment process combining hydrothermal carbonization and aerobic fermentation, successfully achieving harmless treatment of wastes and avoiding the emission of carbon dioxide and other harmful gases caused by traditional incineration. The sterilization treatment of municipal sludge is carried out by high-temperature and high-pressure steam method, which ensures the sterilization effect while avoiding the secondary pollution of the environment by chemical disinfectants. In addition, the "adsorption-fixation-separation" treatment method of heavy metals not only effectively removes heavy metals, but also prevents the migration and diffusion of these harmful substances, thereby improving the safety of organic fertilizers.

[0030] (3) The treatment process of the present invention is reasonably designed, the process is simple, the equipment requirements are relatively low, and the operation is easy to realize industrial promotion and application. The reasonable setting of the particle size and proportion control of the agricultural and forestry waste and the temperature, pressure and time of the hydrothermal carbonization make the treatment process have high stability and controllability, and reduce the production cost. At the same time, the mixing ratio of municipal sludge and carbon-based materials and the optimization of fermentation conditions make the aerobic fermentation process more efficient and faster, further reducing the processing cost and time.

[0031] (4) The organic fertilizer produced by the present invention has balanced nutrients and high biological activity through activation and modification treatment, and has good soil improvement performance. The fertilizer is not only suitable for the planting of various crops, such as cereals, vegetables, fruit trees, etc., but also can significantly improve the soil's water and fertilizer retention capacity, enhance soil microbial activity and increase soil fertility, improve the soil's structure and ecological environment, and promote the sustainable development of agricultural production.

[0032] (5) The organic fertilizer produced by the present invention is not only suitable for the cultivation of field crops, but also suitable for the cultivation of horticultural plants and cash crops. The fertilizer product has high market acceptance and economic benefits, can effectively replace chemical fertilizers, reduce the dependence on chemical fertilizers in agricultural production, and conform to the trend of green agricultural development. In addition, the present invention also has strong environmental benefits, can effectively reduce the negative impact of agricultural production on the environment, and promote the development of agricultural circular economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1This is a flow chart of the preparation method for producing organic fertilizer using waste agricultural and forestry biomass and municipal sludge provided by the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0035] See also Figure 1 The method for producing organic fertilizer using waste agricultural and forestry biomass and municipal sludge comprises the following steps:

[0036] (A) crushing and screening agricultural and forestry wastes such as corn stalks, peanut shells, and wood chips to obtain biomass raw materials;

[0037] (B) subjecting the treated biomass raw material to hydrothermal carbonization to convert it into a carbon-based material rich in organic matter;

[0038] (C) High temperature and high pressure steam sterilization and heavy metal "adsorption-fixation-separation" treatment of municipal sewage sludge;

[0039] (D) mixing the carbon-based material with treated municipal sludge in a certain proportion, and then inoculating a bacterial community for aerobic fermentation, thereby promoting the decomposition of organic matter in the mixture under the action of the microbial community;

[0040] (E) activating and modifying the fermented mixture to obtain an organic fertilizer with balanced nutrients and soil improvement performance.

[0041] Preferably, in step (A), the particle size of the agricultural and forestry waste is controlled at 0.5-2.5 mm, and the proportions of corn stalks, peanut shells and wood chips are 30-50%, 20-40% and 10-30% respectively, so as to improve the conversion efficiency of subsequent hydrothermal carbonization treatment.

[0042] Preferably, in step (B), the temperature of the hydrothermal carbonization treatment is controlled at 180-250° C., the pressure is controlled at 1.5-3.0 MPa, and the treatment time is 1-3 hours to ensure that the biomass raw material is fully carbonized.

[0043] Preferably, in step (C), the sterilization treatment of municipal sludge adopts a high temperature and high pressure steam method, the treatment temperature is 120-150°C, the pressure is 0.15-0.25MPa, and the treatment time is 30-60 minutes.

[0044] Preferably, the heavy metal "adsorption-immobilization-separation" treatment in step (C) comprises the following steps:

[0045] (C1) adding adsorbent materials to municipal sludge, such as zeolite, bentonite or chitosan, to adsorb heavy metals in the sludge;

[0046] (C2) solidifying the adsorbed heavy metals by chemical fixatives, such as phosphates, lime, etc.;

[0047] (C3) Separating the fixed heavy metal particles by gravity separation or centrifugation.

[0048] Preferably, in step (D), the mixing ratio of the carbon-based material to the municipal sludge is 1:2 to 1:5 to achieve the best fermentation effect.

[0049] Preferably, in step (D), the bacterial community includes thermophilic cellulose decomposing bacteria, lactic acid bacteria, yeast and nitrifying bacteria, thereby enhancing the decomposition rate of organic matter and improving the stability of the fermentation product.

[0050] Preferably, in step (D), the aerobic fermentation process is carried out at a temperature of 50-65° C. for 15-25 days, and the compost is turned regularly during the fermentation to ensure sufficient oxygen supply.

[0051] Preferably, in step (E), the activation modification treatment includes adding humic acid, amino acids and seaweed extracts to enhance the nutrient content and biological activity of the organic fertilizer.

[0052] Preferably, the organic fertilizer is suitable for the planting of a variety of crops, including but not limited to the planting of grains, vegetables and fruit trees, and it also has the functions of improving soil structure, increasing soil water and fertilizer retention capacity, enhancing soil microbial activity and increasing soil fertility.

[0053] Embodiment 1:

[0054] This embodiment provides a method for producing high-quality organic fertilizer using waste agricultural and forestry biomass and municipal sludge. First, corn stalks, peanut shells and sawdust are used as the main agricultural and forestry waste raw materials, mixed in a ratio of 50%, 30% and 20%, and these raw materials are crushed so that their particle size is controlled at about 1.0 mm. This particle size control not only improves the efficiency of subsequent hydrothermal carbonization treatment, but also ensures that the raw materials participate in the reaction more evenly during the fermentation process. Next, the treated biomass raw material is placed in a hydrothermal reaction device for hydrothermal carbonization treatment, and the reaction conditions are a temperature of 220°C, a pressure of 2.5MPa, and a duration of 2 hours. In this process, the biomass raw material is converted into a carbon-based material rich in organic matter, and its physical and chemical properties are more suitable for subsequent organic fertilizer production. Subsequently, the municipal sludge is subjected to high temperature and high pressure steam sterilization treatment, the temperature is controlled at 140°C, the pressure is 0.2MPa, and the duration is 45 minutes to ensure that the pathogenic microorganisms in the sludge are completely eliminated. The sterilized sludge is then subjected to heavy metal "adsorption-fixation-separation" treatment. The specific steps include: adding a mixture of zeolite and chitosan (1:1) accounting for 5% of the total mass of the sludge as an adsorbent to effectively adsorb the heavy metals in the sludge; then, using calcium phosphate and lime (1:2) as chemical fixatives to solidify the adsorbed heavy metals, and the addition amount is 3% of the mass of the sludge; finally, the solidified heavy metal particles are separated by centrifugation to ensure that the residual heavy metal content in the sludge meets environmental protection requirements. After completing the above treatment, the carbon-based material is mixed with the treated municipal sludge in a ratio of 1:3, and a mixed bacterial community containing thermophilic cellulose decomposing bacteria, lactic acid bacteria, yeast and nitrifying bacteria is inoculated to promote the decomposition and fermentation of organic matter. Aerobic fermentation is carried out at a temperature of 55°C for 20 days, and the pile is turned every 5 days to ensure sufficient oxygen supply during the fermentation process, thereby obtaining a stable fermentation product. Finally, the fermentation product is activated and modified by adding 3% humic acid, 1% amino acid and 0.5% seaweed extract to the total material to obtain high-quality organic fertilizer.

[0055] Embodiment 2:

[0056] This embodiment provides a method for producing high-quality organic fertilizer using waste agricultural and forestry biomass and municipal sludge. First, corn stalks, peanut shells and sawdust are used as the main agricultural and forestry waste raw materials, mixed in a ratio of 45%, 40% and 15%, and these raw materials are crushed so that their particle size is controlled at about 1.5 mm. This particle size control not only improves the efficiency of subsequent hydrothermal carbonization treatment, but also ensures that the raw materials participate in the reaction more evenly during the fermentation process. Next, the treated biomass raw material is placed in a hydrothermal reaction device for hydrothermal carbonization treatment, and the reaction conditions are a temperature of 230 ° C, a pressure of 2.2 MPa, and a duration of 1.5 hours. In this process, the biomass raw material is converted into a carbon-based material rich in organic matter, and its physical and chemical properties are more suitable for subsequent organic fertilizer production. Subsequently, the municipal sludge is subjected to high temperature and high pressure steam sterilization treatment, the temperature is controlled at 130 ° C, the pressure is 0.18 MPa, and the duration is 50 minutes to ensure that the pathogenic microorganisms in the sludge are completely eliminated. The sterilized sludge is then subjected to heavy metal "adsorption-fixation-separation" treatment. The specific steps include: adding a mixture of bentonite and chitosan (2:1) accounting for 3% of the total mass of the sludge as an adsorbent to effectively adsorb the heavy metals in the sludge; then, potassium phosphate and lime (1:2) are used as chemical fixatives to solidify the adsorbed heavy metals, and the addition amount is 2% of the mass of the sludge; finally, the solidified heavy metal particles are separated by centrifugation to ensure that the residual heavy metal content in the sludge meets environmental protection requirements. After completing the above treatment, the carbon-based material is mixed with the treated municipal sludge in a ratio of 1:4, and a mixed bacterial community containing thermophilic cellulose decomposing bacteria, lactic acid bacteria, yeast and nitrifying bacteria is inoculated to promote the decomposition and fermentation of organic matter. Aerobic fermentation is carried out at a temperature of 60°C for 22 days, and the pile is turned every 3 days to ensure sufficient oxygen supply during the fermentation process, thereby obtaining a stable fermentation product. Finally, the fermentation product is activated and modified by adding 2% humic acid, 2% amino acid and 2% seaweed extract to the total material to obtain high-quality organic fertilizer.

[0057] Embodiment 3:

[0058] This embodiment provides a method for producing high-quality organic fertilizer using waste agricultural and forestry biomass and municipal sludge. First, corn stalks, peanut shells and sawdust are used as the main agricultural and forestry waste raw materials, mixed in a ratio of 40%, 40% and 20%, and these raw materials are crushed so that their particle size is controlled at about 2.0 mm. This particle size control not only improves the efficiency of subsequent hydrothermal carbonization treatment, but also ensures that the raw materials participate in the reaction more evenly during the fermentation process. Next, the treated biomass raw material is placed in a hydrothermal reaction device for hydrothermal carbonization treatment, and the reaction conditions are a temperature of 250°C, a pressure of 2.2MPa, and a duration of 3 hours. In this process, the biomass raw material is converted into a carbon-based material rich in organic matter, and its physical and chemical properties are more suitable for subsequent organic fertilizer production. Subsequently, the municipal sludge is subjected to high temperature and high pressure steam sterilization treatment, the temperature is controlled at 150°C, the pressure is 0.22MPa, and the duration is 30 minutes to ensure that the pathogenic microorganisms in the sludge are completely eliminated. The sterilized sludge is then subjected to heavy metal "adsorption-fixation-separation" treatment. The specific steps include: adding a mixture of bentonite and chitosan (1:1) accounting for 4% of the total mass of the sludge as an adsorbent to effectively adsorb the heavy metals in the sludge; then, potassium phosphate and lime (1:1) are used as chemical fixatives to solidify the adsorbed heavy metals, and the addition amount is 3% of the mass of the sludge; finally, the solidified heavy metal particles are separated by centrifugation to ensure that the residual heavy metal content in the sludge meets environmental protection requirements. After completing the above treatment, the carbon-based material is mixed with the treated municipal sludge in a ratio of 1:2, and a mixed bacterial community containing thermophilic cellulose decomposing bacteria, lactic acid bacteria, yeast and nitrifying bacteria is inoculated to promote the decomposition and fermentation of organic matter. Aerobic fermentation is carried out at a temperature of 55°C for 20 days, and the pile is turned every 4 days to ensure sufficient oxygen supply during the fermentation process, thereby obtaining a stable fermentation product. Finally, the fermentation product is activated and modified by adding 1.5% humic acid, 1.5% amino acid and 2.5% seaweed extract to the total material to obtain high-quality organic fertilizer.

[0059] Comparative Example 1:

[0060] This comparative study purchased organic fertilizer products sold by a company in Shijiazhuang, Hebei Province as a comparison. The main raw materials of this product are chicken manure and cow manure.

[0061] Comparative Example 2:

[0062] This comparative example purchases an organic fertilizer product sold by a company in Qingdao, Shandong as a comparison. The main raw materials of this product are bean cake residue and chicken manure.

[0063] Comparison of organic fertilizer index test results:

[0064] According to industry standards, a third-party agricultural testing agency in Wuhan was commissioned to test the organic fertilizers provided in the above three embodiments and two comparative examples. The results and analysis are as follows.

[0065] Table 1 is a comparison of the technical index test results of several organic fertilizers.

[0066] Organic matter is one of the key indicators for measuring the quality of organic fertilizers, which directly affects the improvement of soil structure and the activity of soil microorganisms. According to the data in Table 1, the mass fractions of organic matter in Example 1, Example 2 and Example 3 are 55.2%, 52.8% and 53.3%, respectively, which are significantly higher than 42.3% of Comparative Example 1 and 39.5% of Comparative Example 2. This shows that the organic fertilizer provided by the present invention can more effectively increase the organic matter content of the soil, improve soil fertility and water retention capacity, and contribute to sustainable development in agricultural production.

[0067] Total nutrients include nitrogen, phosphorus, potassium and other major nutrient elements required for crop growth, and their content is directly related to the fertilizer efficiency of organic fertilizer. The total nutrient mass fractions of Example 1, Example 2 and Example 3 are 23.6%, 22.9% and 23.5% respectively, far exceeding 13.9% of Comparative Example 1 and 15.7% of Comparative Example 2. This means that the organic fertilizer of the present invention can better promote the healthy growth of crops and increase yield while providing rich nutrition.

[0068] Moisture content is one of the important indicators for evaluating the quality stability of organic fertilizers. The moisture contents of Example 1, Example 2 and Example 3 are all about 12%, which are much lower than 13.5% of Comparative Example 1 and 15.2% of Comparative Example 2. The lower moisture content indicates that the organic fertilizer product of the present invention is more stable, is not easy to decompose or deteriorate during storage, and has better use effect.

[0069] The pH value affects the availability of nutrients and the activity of microorganisms in the soil. The pH values ​​of Examples 1, 2, and 3 are all 7.0, which is within the appropriate range of 5.5 to 8.5 and in the neutral range, suitable for the growth of most crops. In contrast, the pH values ​​of Comparative Examples 1 and 2 are 7.2 and 7.1, respectively, which are also within a reasonable range, but slightly alkaline, which may have an adverse effect on certain acidic soils or crops.

[0070] The seed germination index is an important indicator for evaluating whether the organic fertilizer contains substances that inhibit seed germination. The seed germination indexes of Example 1, Example 2 and Example 3 are 98.5%, 97.9% and 97.7% respectively, which are significantly higher than 92.1% of Comparative Example 1 and 91.6% of Comparative Example 2. This shows that the organic fertilizer product of the present invention has a promoting effect on the germination of crop seeds, does not contain harmful substances that inhibit germination, and is more suitable for use in agricultural production.

[0071] Mechanical impurities can affect the uniformity and application effect of organic fertilizers. The mechanical impurities in Example 1, Example 2 and Example 3 are 0.08%, 0.06% and 0.06% respectively, which are much lower than 0.12% in Comparative Example 1 and 0.28% in Comparative Example 2. The lower content of mechanical impurities shows that the organic fertilizer product of the present invention has higher purity, which is conducive to the uniform application of fertilizers and the absorption and utilization of crops.

[0072] Table 1 Comparison of technical index test results of several organic fertilizers

[0073]

[0074]

[0075] Next, Table 2 compares the limit index test results of several organic fertilizers.

[0076] Arsenic is a harmful heavy metal, and excessive intake can cause pollution to soil and crops. The arsenic content in Example 1, Example 2 and Example 3 is 1.23 mg / kg, 1.18 mg / kg and 1.19 mg / kg, respectively, which is much lower than 5.98 mg / kg of Comparative Example 1 and 8.36 mg / kg of Comparative Example 2. This shows that the organic fertilizer of the present invention has lower environmental risks and is conducive to the sustainable development of agriculture.

[0077] Mercury is a highly toxic substance that is seriously harmful to the environment and human health. The mercury content in Example 1, Example 2 and Example 3 was not detected, while the mercury content in Comparative Example 1 and Comparative Example 2 was 0.05 mg / kg and 0.03 mg / kg respectively. The organic fertilizer product of the present invention shows an absolute advantage in mercury content, avoiding the potential risk of mercury pollution.

[0078] Lead pollution has great harm to crop growth and human health. The lead contents of Example 1, Example 2 and Example 3 are 5.26 mg / kg, 3.28 mg / kg and 3.59 mg / kg respectively, which are significantly lower than 15.59 mg / kg of Comparative Example 1 and 14.25 mg / kg of Comparative Example 2. The organic fertilizer of the present invention can effectively reduce the accumulation of lead in the soil and avoid the harm caused by lead pollution.

[0079] Cadmium is a highly toxic heavy metal that can harm the human body through the soil-plant system. The cadmium contents of Example 1, Example 2 and Example 3 are 0.15 mg / kg, 0.29 mg / kg and 0.31 mg / kg, respectively, which are much lower than 1.85 mg / kg of Comparative Example 1 and 2.11 mg / kg of Comparative Example 2. This shows that the organic fertilizer product of the present invention is more effective in controlling soil cadmium pollution and is more environmentally friendly.

[0080] Chromium accumulates in the soil for a long time and can cause environmental pollution. The chromium contents of Example 1, Example 2 and Example 3 are 26.8 mg / kg, 34.7 mg / kg and 29.5 mg / kg, respectively, which are significantly lower than 88.3 mg / kg of Comparative Example 1 and 95.6 mg / kg of Comparative Example 2. The organic fertilizer product of the present invention has obvious advantages in controlling heavy metal chromium and helps to reduce chromium pollution in agricultural soil.

[0081] The fecal coliform count is an important indicator reflecting the content of pathogens in organic fertilizers. The fecal coliform counts of Example 1, Example 2, and Example 3 were 15 / g, 18 / g, and 17 / g, respectively, which were much lower than 68 / g of Comparative Example 1 and 59 / g of Comparative Example 2, showing excellent hygienic safety and reducing the risk of pathogen transmission.

[0082] Ascaris egg mortality is an important indicator for evaluating the hygienic safety of organic fertilizers. The ascaris egg mortality of Examples 1, 2 and 3 is 99.8% and 99.9%, respectively, which is higher than 96.8% of Comparative Example 1 and 97.2% of Comparative Example 2. This indicates that the organic fertilizer of the present invention performs better in terms of hygienic safety and can better prevent crops and the environment from being contaminated by ascaris eggs.

[0083] Table 2 Comparison of test results of limit indicators of several organic fertilizers

[0084] project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Total arsenic (As), mg / kg 1.23 1.18 1.19 5.98 8.36 Total mercury (Hg), mg / kg Not detected Not detected Not detected 0.05 0.03 Total lead (Pb), mg / kg 5.26 3.28 3.59 15.59 14.25 Total cadmium (Cd), mg / kg 0.15 0.29 0.31 1.85 2.11 Total chromium (Cr), mg / kg 26.8 34.7 29.5 88.3 95.6 Fecal coliform count, pieces / g 15 18 17 68 59 Ascaris egg mortality, % 99.8 99.9 99.8 96.8 97.2

[0085] In summary, 3 embodiments of the present invention are superior to the organic fertilizer product of the comparative example in technical indicators such as organic matter content, total nutrients, moisture content, seed germination index, mechanical impurities, etc., showing higher fertilizer efficiency and stability. In terms of limit index, the organic fertilizer product of the present invention is far superior to the comparative example in terms of total arsenic, total mercury, total lead, total cadmium, total chromium, fecal coliform group number and ascaris egg mortality, showing that it has lower environmental and health risks, meets the requirements of modern agriculture for environmental protection and sustainable development. Therefore, the organic fertilizer provided by the present invention has obvious advantages, and is a safer, more efficient and environmentally friendly fertilizer selection.

[0086] The above is only a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A method for producing organic fertilizer using waste agricultural and forestry biomass and municipal sludge, characterized in that: The following steps are involved: (A) crushing and screening agricultural and forestry waste to obtain biomass raw materials; (B) subjecting the treated biomass raw material to hydrothermal carbonization to convert it into a carbon-based material rich in organic matter; (C) High temperature and high pressure steam sterilization and heavy metal "adsorption-fixation-separation" treatment of municipal sewage sludge; (D) mixing the carbon-based material with treated municipal sludge in a certain proportion, and then inoculating a bacterial community for aerobic fermentation, thereby promoting the decomposition of organic matter in the mixture under the action of the microbial community; (E) activating and modifying the fermented mixture to obtain an organic fertilizer with balanced nutrients and soil improvement performance.

2. The method according to claim 1, characterized in that In the step (A), the particle size of the agricultural and forestry waste is controlled to be 0.5-2.5 mm, and the proportions of corn stalks, peanut shells and wood chips are 30-50%, 20-40% and 10-30% respectively.

3. The method according to claim 1, characterized in that In the step (B), the temperature of the hydrothermal carbonization treatment is controlled at 180-250° C., the pressure is controlled at 1.5-3.0 MPa, and the treatment time is 1-3 hours to ensure that the biomass raw material is fully carbonized.

4. The method according to claim 1, characterized in that In the step (C), the municipal sludge is sterilized by high temperature and high pressure steam method, the treatment temperature is 120-150° C., the pressure is 0.15-0.25 MPa, and the treatment time is 30-60 minutes.

5. The method according to claim 1, characterized in that The heavy metal "adsorption-fixation-separation" treatment in step (C) comprises the following steps: (C1) adding adsorbent materials to municipal sludge to adsorb heavy metals in the sludge; (C2) Immobilization of adsorbed heavy metals by chemical fixatives; (C3) Separating the fixed heavy metal particles by gravity separation or centrifugation.

6. The method according to claim 1, characterized in that In the step (D), the mixing ratio of the carbon-based material to the municipal sludge is 1:2 to 1:

5.

7. The method according to claim 1, characterized in that In the step (D), the bacterial community includes thermophilic cellulose decomposing bacteria, lactic acid bacteria, yeast and nitrifying bacteria.

8. The method according to claim 1, characterized in that: In the step (D), the aerobic fermentation process is carried out at a temperature of 50-65° C. for 15-25 days, and the compost is turned regularly during the fermentation period.

9. The method according to claim 1, characterized in that: In the step (E), the activation modification treatment includes adding humic acid, amino acid and seaweed extract.

10. The method according to any one of claims 1 to 9, characterized in that: The organic fertilizer is suitable for planting various crops, including grains, vegetables and fruit trees.

Images