Organic-inorganic sintered fertilizer taking sludge and biogas residues as main materials and preparation method thereof

Abstract

The invention discloses an organic-inorganic sintered fertilizer using sludge and biogas residue as main materials and a preparation method thereof, the preparation method comprises the following steps: (1) weighing calcium superphosphate and potassium chloride, and uniformly mixing to obtain an inorganic fertilizer; (2) weighing the sludge cake and the biogas residue, and uniformly mixing the sludge cake and the biogas residue to obtain a mixture A; uniformly mixing the mixture A with an inorganic fertilizer to obtain a mixture B; and (3) mixing the mixture B with calcium powder, extruding the mixture to prepare columnar particles, drying the columnar particles in a constant-temperature drying box, putting the columnar particles into a muffle furnace, carrying out oxygen-isolated pyrolysis at 400-450 DEG C for 60-70 minutes, and carrying out curing treatment to obtain the stable organic-inorganic sintered fertilizer. According to the organic-inorganic sintered fertilizer, the municipal sludge is used as a main raw material, the biogas residues are used as a mixed auxiliary material, the organic-inorganic sintered fertilizer is not subjected to a fermentation and decomposition step, and the organic-inorganic sintered fertilizer contains a large amount of cellulose materials, so that the organic-inorganic sintered fertilizer is beneficial to nutrient storage and retention, is also beneficial to improvement of soil physical properties and soil microflora, and can promote resource utilization.

Description

Technical Field

[0001] This invention belongs to the field of fertilizer preparation technology, specifically relating to an organic-inorganic sintered fertilizer with sludge and biogas residue as the main materials and its preparation method. Background Technology

[0002] Sludge is a byproduct of wastewater treatment, with a massive annual output. It is estimated that in 2020, my country's annual municipal sludge production reached 60 million tons (based on an 80% moisture content). With rapid urbanization, the annual sludge production is expected to continue to increase year by year, exceeding 90 million tons by 2025. Common sludge treatment and disposal methods include land application (agricultural use), building material processing, pyrolysis, and sanitary landfill. Among these, pyrolysis, with its advantages of reducing sludge volume and rendering it harmless, is becoming the preferred method for sludge management. However, direct pyrolysis of sludge, due to its high moisture content, is not only technically expensive but also results in insufficient pyrolysis, producing pyrolysis ash that poses a potential environmental hazard.

[0003] With the adjustment of rural industrial structure and the implementation of new rural construction, my country's biogas engineering construction has developed rapidly in the past decade. However, while biogas projects have shown economic benefits, they have also generated a large amount of anaerobic fermentation byproducts—biogas residue and biogas slurry. Statistics show that my country's annual production of biogas residue and biogas slurry reaches as high as 400 million tons. For a long time, the main method of biogas fertilizer disposal has been the return of biogas residue and biogas slurry to the fields as biogas fertilizer.

[0004] However, existing sludge or biogas residue fertilizers require a long fermentation and composting process before they can be used. This process is time-consuming, requires a large area, and is costly, which hinders its widespread application.

[0005] Therefore, how to provide a simple method for preparing fertilizer from sludge and biogas residue is a technical problem that those skilled in the art continue to solve. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned technical problems and provide an organic-inorganic sintered fertilizer with sludge and biogas residue as the main materials and its preparation method.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing an organic-inorganic sintered fertilizer mainly composed of sludge and biogas residue includes the following steps: (1) Weigh out superphosphate and potassium chloride, mix them evenly to obtain inorganic fertilizer; (2) Weigh out the sludge cake and biogas residue, mix them evenly to obtain mixture A; mix the obtained mixture A with the inorganic fertilizer prepared in step (1) evenly to obtain mixture B; (3) Mix the mixture B obtained in step (2) with calcium powder and then extrude it to make columnar particles. After drying in a constant temperature drying oven, put it into a muffle furnace and pyrolyze it in the absence of air at 400~450℃ for 60~70 minutes. After curing, a stable organic-inorganic sintered fertilizer is obtained.

[0008] Preferably, the mass ratio of superphosphate to potassium chloride in step (1) is 1:0.8~1.2.

[0009] Preferably, the sludge cake in step (2) has a moisture content of 70-75% and an organic matter content of ≥300g / kg; the biogas residue has a moisture content of ≤8% and a cellulose content of ≥63%, and is dried at a high temperature of 250-400℃.

[0010] Preferably, the biogas residue mentioned in step (2) is biogas residue obtained by anaerobic fermentation of livestock and poultry manure or straw raw materials and solid-liquid separation; the livestock and poultry manure is one or more of cow manure, chicken manure, and pig manure; the straw is one or more of corn straw, vegetable straw, wheat straw, and rice straw.

[0011] Preferably, in step (2), the mass ratio of sludge cake to biogas residue is 2~4:1; and the mass ratio of mixture A to inorganic fertilizer is 2~4:1.

[0012] Preferably, in step (3), the mass ratio of mixture B to calcium powder is 80~120:2; the heating rate during pyrolysis is 15~25℃ / min; the drying temperature is 50-60℃; and the moisture content of the columnar particles after drying is 15-20%.

[0013] Preferably, the columnar particles in step (3) have a diameter of 5-7 mm and a height of 5-6 mm.

[0014] Preferably, the curing process in step (3) is as follows: the pyrolyzed particles are transferred to a sealed curing room for curing. The curing conditions are: temperature 20-40℃, relative humidity 65-75%, and curing time 2-3 days.

[0015] The beneficial effects of this invention are as follows: 1. The organic-inorganic sintered fertilizer of the present invention uses urban sludge and biogas residue as the main raw materials. It does not undergo fermentation and composting. Biogas residue contains about 30% organic matter, which helps to store and retain nutrients and improves soil physical properties and soil microbial flora. The nitrogen, phosphorus and potassium elements contained in urban sludge can provide nutrients for soil crops. Using urban sludge as the main raw material can promote the resource utilization of sludge from urban sewage treatment plants.

[0016] 2. The organic-inorganic sintered fertilizer of the present invention uses biogas residue as a mixed auxiliary material. It does not undergo fermentation and composting steps. The biogas residue retains more cellulose material, which not only helps to store and retain nutrients, but also helps to improve soil physical properties and soil microbial flora. Furthermore, the use of biogas residue as an auxiliary material can promote the resource utilization of agricultural and forestry waste biomass.

[0017] 3. The organic-inorganic sintered fertilizer of the present invention contains 17-27% nitrogen, phosphorus and potassium nutrients, and 8-18% exogenous chemical fertilizer nutrients. The ratio of nitrogen, phosphorus and potassium is scientific and suitable for the nutrient requirements of rice.

[0018] 4. When the organic-inorganic sintered fertilizer of the present invention is applied to crop planting, the yield increase effect is significant, and it has significant effects such as environmental friendliness, improvement of soil quality and mitigation of agricultural non-point source pollution, and has broad industrialization prospects.

[0019] 5. The organic-inorganic sintered fertilizer of the present invention has a low production cost, a simple preparation process, and does not require fermentation or composting, thus effectively reducing the fertilizer production cycle and procedures. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the following embodiments of the present invention, the sludge was taken from the Fenghuang Wastewater Treatment Plant in Huzhou City, Zhejiang Province. The sludge was obtained by concentration and centrifugation, with a water content of 72% and an organic matter content of 500g / kg.

[0022] The biogas residue was taken from Zhejiang Yijing Animal Husbandry Co., Ltd. It was made from cow manure through anaerobic fermentation and biogas fermentation. After solid-liquid separation and drying, the biogas residue had a moisture content of 12.34% and an organic matter content of 63.01%.

[0023] Example 1 An organic-inorganic sintered fertilizer with sludge and biogas residue as the main materials uses the following amounts of raw materials: 6 kg sludge, 2 kg superphosphate, 2 kg potassium chloride, 3 kg biogas residue, and 0.4 kg calcium powder.

[0024] The preparation method is as follows: (1) Weigh 2 kg of superphosphate and 1.6 kg of potassium chloride and mix them evenly to obtain inorganic fertilizer; (2) Weigh 6 kg of sludge cake and 3 kg of biogas residue, mix them evenly to obtain mixture A; mix the obtained mixture A with the inorganic fertilizer prepared in step (1) evenly to obtain mixture B; (3) Mix the mixture B obtained in step (2) with calcium powder and then extrude it to make columnar particles with a diameter of 6 mm and a height of 5 mm. After drying in a constant temperature drying oven, put it into a muffle furnace and pyrolyze it at 450°C in the absence of air for 70 min. After curing, a stable organic-inorganic sintered fertilizer is obtained. The heating rate during pyrolysis is 20°C / min. The drying temperature is 55°C. The moisture content of the columnar particles after drying is about 17%. The curing process is as follows: transfer the pyrolyzed particles into a sealed curing room for curing. Curing conditions: temperature 30°C, relative humidity 70%, curing time 2 days.

[0025] Example 2 The quantities of raw materials used in this embodiment are: 9 kg of sludge, 2 kg of superphosphate, 2 kg of potassium chloride, 3 kg of biogas residue, and 0.4 kg of calcium powder.

[0026] The preparation method is the same as in Example 1.

[0027] Example 3 The quantities of raw materials used in this embodiment are: 12 kg of sludge, 2 kg of superphosphate, 2 kg of potassium chloride, 3 kg of biogas residue, and 0.4 kg of calcium powder.

[0028] The preparation method is the same as in Example 1.

[0029] Comparative Example 1, The scheme differs from that in Example 1: the pyrolysis temperature is 300℃, while other conditions remain unchanged.

[0030] Comparative Example 2 The scheme differs from that in Example 1, where the pyrolysis temperature is 600°C.

[0031] Comparative Example 3 The scheme differs from that in Example 1, where the pyrolysis time is 50 minutes.

[0032] Comparison of Implementation Results The product properties of the above embodiments and comparative examples are shown in Table 1.

[0033] Table 1. Product properties of examples and comparative examples

[0034] As can be seen from Table 1, the sintered fertilizer is a complete columnar granule in the form of carbon black, with an organic matter content of more than 20%, a potassium content of 9-12%, a phosphorus content of 4-6%, a nitrogen content of 1-2%, and a total nutrient content of more than 15%. It can be used as a base fertilizer in combination with other chemical fertilizers.

[0035] When the pyrolysis temperature is low (Comparative Example 1), although the organic matter content is high, the product's appearance is gray, indicating light carbonization, which is not conducive to commercial sales. Conversely, excessively high pyrolysis temperatures (Comparative Example 2) severely reduce the product's organic matter and nitrogen content, while also consuming too much heat energy, making it unrecommended. When the pyrolysis time is less than 60 minutes (Comparative Example 3), the product's appearance also turns gray, or even appears muddy, which is detrimental to sales and promotion.

[0036] Application Example 1. The effect of sintered fertilizer on watermelon yield Two watermelon experimental plots were selected for field trials. Each plot had identical conditions and was 100 square meters in size, designated as Experimental Plot 1 and Experimental Plot 2. Experimental Plot 2 used a commercially available chicken-sheep mixed nitrogen-phosphorus-potassium fertilizer (China Agricultural Inputs Compound Fertilizer N-P2O5-K2O14-16-15, total nutrients ≥45%), while Experimental Plot 1 used the organic-inorganic sintered fertilizer prepared in Example 1, supplemented with nitrogen fertilizer (the amount of nitrogen fertilizer and the total amount of phosphorus and potassium fertilizer were the same as in Experimental Plot 2). After the watermelons matured and were harvested, the watermelons from the two plots were compared: the watermelon seedlings in Experimental Plot 1 sprouted earlier, had well-developed root systems, thicker stems, faster growth, higher sweetness, and fewer pests and diseases. The average yield per mu was 6550 kg, compared to the average yield of 5980 kg per mu in Experimental Plot 2, representing a yield increase of 12.88%.

[0037] Application Example 2. The Effect of Sintered Fertilizer on Wheat Yield Two wheat experimental plots were selected for field trials. Each plot had identical conditions and an area of ​​100 square meters, designated as Experimental Plot 1 and Experimental Plot 2. Experimental Plot 2 used commercially available nitrogen, phosphorus, and potassium fertilizer (China Agricultural Inputs Maihuangjin Wheat-Specific Fertilizer), while Experimental Plot 1 used the organic-inorganic sintered fertilizer prepared in Example 2, supplemented with nitrogen fertilizer (the amount of nitrogen fertilizer and the total amount of phosphorus and potassium fertilizer were the same as in Experimental Plot 2). After wheat maturity and harvest, the two experimental plots were compared: wheat seedlings in Experimental Plot 1 emerged faster, exhibited stronger drought, cold, and lodging resistance, higher sugar content, better taste, and better storage and transportability. The average yield per mu (667 square meters) of wheat in Experimental Plot 1 was 13.42% higher than that in Experimental Plot 2.

[0038] Application Example 3. The Impact of Sintered Fertilizer on Corn Yield Two maize experimental fields were selected for field trials. Each field had identical conditions and was 200 square meters in size, designated as Experimental Field 1 and Experimental Field 2. Experimental Field 2 used a general-purpose NPK fertilizer (China Agricultural Inputs Compound Fertilizer N-P2O5-K2O 15-15-15, total nutrients ≥45%), while Experimental Field 1 used the organic-inorganic sintered fertilizer prepared in Example 3, supplemented with nitrogen fertilizer (the amount of nitrogen fertilizer and the total amount of phosphorus and potassium fertilizer were the same as in Experimental Field 2). After maize maturity and harvest, the two experimental fields were compared: the maize kernels in Experimental Field 1 were larger and fuller, free from pests and diseases, with robust roots and stems, and the soil was not compacted. The maize yield was higher, with an average yield increase of 11.04% per mu.

[0039] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0040] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An organic-inorganic sintered fertilizer mainly composed of sludge and biogas residue, and its preparation method, characterized in that, Includes the following steps: (1) Weigh out superphosphate and potassium chloride, mix them evenly to obtain inorganic fertilizer; (2) Weigh out the sludge cake and biogas residue, mix them evenly to obtain mixture A; mix the obtained mixture A with the inorganic fertilizer prepared in step (1) evenly to obtain mixture B; (3) Mix the mixture B obtained in step (2) with calcium powder and then extrude it into columnar particles. After drying in a constant temperature drying oven, put it into a muffle furnace and pyrolyze it at 400~450℃ in the absence of air for 60~70 minutes. After curing, a stable organic-inorganic sintered fertilizer is obtained.

2. The method for preparing an organic-inorganic sintered fertilizer based on sludge and biogas residue as described in claim 1, characterized in that, In step (1), the mass ratio of superphosphate to potassium chloride is 1:0.8~1.

2.

3. The method for preparing an organic-inorganic sintered fertilizer based on sludge and biogas residue as described in claim 1, characterized in that, The sludge cake mentioned in step (2) has a moisture content of 70-75% and an organic matter content of ≥150g / kg; the biogas residue has a moisture content of ≤8%, a cellulose content of ≥63%, and an organic matter content of ≥400g / kg.

4. The method for preparing an organic-inorganic sintered fertilizer based on sludge and biogas residue as described in claim 1, characterized in that, The biogas residue mentioned in step (2) is the biogas residue obtained after solid-liquid separation of biogas slurry from a normally operating biogas project; the straw is one or a combination of two or more of corn straw, vegetable straw, wheat straw, and rice straw.

5. The method for preparing an organic-inorganic sintered fertilizer based on sludge and biogas residue as described in claim 1, characterized in that, In step (2), the mass ratio of sludge cake to biogas residue is 2~4:1; the mass ratio of mixture A to inorganic fertilizer is 2~4:

1.

6. The method for preparing an organic-inorganic sintered fertilizer based on sludge and biogas residue as described in claim 1, characterized in that, In step (3), the mass ratio of mixture B to calcium powder is 80~120:2; the heating rate during pyrolysis is 15~25℃ / min; the drying temperature is 50-60℃, and the moisture content of the columnar particles after drying is 15-20%.

7. The method for preparing an organic-inorganic sintered fertilizer based on sludge and biogas residue as described in claim 1, characterized in that, The columnar particles described in step (3) have a diameter of 5-7 mm and a height of 5-6 mm.

8. The method for preparing an organic-inorganic sintered fertilizer based on sludge and biogas residue as described in claim 1, characterized in that, The curing process described in step (3) is as follows: the pyrolyzed particles are transferred to a sealed curing room for curing. The curing conditions are: temperature 20-40℃, relative humidity 65-75%, and curing time 2-3 days.

9. The organic-inorganic sintered fertilizer prepared by the preparation method according to any one of claims 1-8, with sludge and biogas residue as the main materials.

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