Method for preparing phosphorus-rich organic fertilizer from phosphogypsum compost
By adding phosphogypsum to livestock and poultry manure and inoculating it with phosphate-solubilizing and polyphosphate-accumulating bacteria, the aerobic composting process was optimized, solving the problem of recycling and processing livestock and poultry manure and phosphogypsum, improving the bioavailability and utilization rate of phosphorus, and promoting sustainable agricultural development and environmental protection.
Patent Information
- Application Number
- CN202610434373.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-03
- Publication Date
- 2026-05-26
AI Technical Summary
The recycling and treatment of livestock and poultry manure and phosphogypsum, as well as the utilization of phosphorus resources, are difficult, leading to environmental pollution and resource waste. The impact of existing composting and fermentation methods on phosphorus conversion mechanisms is unclear, resulting in low phosphorus utilization rates.
By introducing phosphate-solubilizing bacteria and polyphosphate-accumulating bacteria, the aerobic composting process is optimized. This is achieved by adding phosphogypsum to livestock and poultry manure and inoculating phosphate-solubilizing bacteria and polyphosphate-accumulating bacteria during the composting process. The phosphate-solubilizing bacteria utilize organic acids and phosphatases secreted by the phosphate-solubilizing bacteria to convert insoluble phosphorus, while the polyphosphate-accumulating bacteria increase the phosphorus content of the microbial biomass, thereby promoting the bioavailability of phosphorus.
It significantly improves the bioavailability and utilization rate of phosphorus, enhances soil fertility, reduces environmental pollution, and provides a scientific basis for the efficient treatment and resource utilization of livestock and poultry manure and phosphogypsum.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of organic fertilizer technology, and specifically, it relates to a method for producing phosphorus-rich organic fertilizer by using phosphate-solubilizing bacteria and polyphosphate-accumulating bacteria in combination with phosphogypsum compost. Background Technology
[0002] With global population growth, socio-economic development, and improved living standards, the demand for meat, eggs, milk, and other livestock and poultry products is constantly increasing, leading to the rapid expansion of the livestock and poultry farming industry. In particular, China's livestock industry has experienced significant growth over the past 50 years, with total output increasing by 13.3%, and the discharge of livestock and poultry manure has also increased significantly. According to data from the Ministry of Agriculture and Rural Affairs, my country's annual production of livestock and poultry manure is 3.8 billion tons. The indiscriminate discharge or direct application of large amounts of livestock and poultry manure to farmland easily causes regional agricultural non-point source pollution. At the same time, livestock and poultry manure contains large amounts of nutrients necessary for plant growth, such as nitrogen, phosphorus, and potassium. Among these, phosphorus, as an essential element for plant growth, plays an irreplaceable role in agricultural production. Research reports that as of 2016, the total phosphorus (P2O5) content in my country's livestock and poultry manure reached 11.5 million tons, accounting for 138.2% of the phosphorus fertilizer applied that year. This indicates that the utilization of livestock and poultry manure as fertilizer has enormous potential in replacing mineral phosphate fertilizers to supplement phosphorus in farmland soil. Surveys show that the production of phosphate fertilizer, a fundamental substance in agricultural production, consumes over 80% of my country's phosphate rock resources. In 2023, China used 14.4359 million tons of chemical phosphate fertilizer (measured as pure P2O5). Meanwhile, the ever-increasing demand for grain production has highlighted the inadequacy of my country's sustainable phosphate rock resource security, urgently requiring the discovery of more environmentally friendly and sustainable phosphate fertilizer production methods. Therefore, promoting the efficient utilization of phosphorus in livestock and poultry manure is not only crucial for the sustainable development of agricultural production but also of great significance in alleviating the phosphorus resource shortage problem.
[0003] Phosphorus in livestock and poultry manure mainly exists in extractable forms, with a high proportion of inorganic phosphorus. If discharged directly into the environment without proper treatment, it can lead to eutrophication, causing algal blooms, oxygen depletion, and other ecological problems, seriously threatening aquatic environmental safety. Currently, composting and fermentation are two common methods for treating livestock and poultry manure. Composting is a traditional method that primarily degrades organic matter through natural fermentation; while fermentation is a more modern method that accelerates the decomposition and transformation of organic matter by controlling temperature, humidity, and aeration. However, the impact of different treatment methods on the phosphorus transformation mechanism, phosphorus form, and bioavailability in livestock and poultry manure remains unclear. Further systematic research will help optimize livestock and poultry manure treatment processes and achieve efficient recovery and utilization of phosphorus. Furthermore, the phosphorus content and form characteristics of manure from different animals also vary significantly. For example, pig manure typically has a high phosphorus content, but its phosphorus forms are mainly insoluble inorganic phosphorus, resulting in low phosphorus utilization when directly applied to the soil. Cow manure, on the other hand, has a relatively low phosphorus content, but a higher proportion of easily mineralized organic phosphorus. Therefore, clarifying the phosphorus characteristics of different animal manure composts will facilitate the precise resource utilization of different types of livestock and poultry manure and improve phosphorus utilization efficiency.
[0004] Besides livestock and poultry manure, phosphogypsum, a byproduct of the phosphate chemical industry, also contains abundant phosphorus resources. However, the phosphorus in it is mostly insoluble, resulting in low utilization. Statistics show that my country currently has over 800 million tons of phosphogypsum stockpiles, with an annual production of 80 million tons. The large accumulation of phosphogypsum not only occupies land resources but also pollutes water bodies, the atmosphere, and soil. Against this backdrop, developing a new type of phosphate fertilizer that can effectively utilize phosphogypsum and livestock and poultry manure while improving soil fertility and reducing environmental pollution is particularly urgent. Summary of the Invention
[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for producing phosphorus-rich organic fertilizer by gypsum composting, so as to solve the problem of difficulty in recycling and processing livestock and poultry manure and phosphogypsum and in the resource utilization of phosphorus.
[0006] To achieve the above-mentioned technical objectives, the inventors have significantly improved the bioavailability of phosphorus in livestock and poultry manure and phosphogypsum compost by introducing phosphate-solubilizing bacteria and continuously optimizing the process steps and technical parameters of aerobic composting. Specifically, the objective of this invention is achieved as follows: a method for producing phosphorus-rich organic fertilizer from phosphogypsum compost, the method comprising the following steps:
[0007] (1) Weigh out the sawdust and livestock manure in proportion, mix them evenly to obtain the mixture;
[0008] (2) Add phosphogypsum to the mixture obtained in step (1) in proportion, mix evenly to obtain compost material;
[0009] (3) Add the compost material obtained in step (1) into a closed reactor, adjust the moisture content, and then inoculate with phosphorus-solubilizing bacteria for aerobic composting. During the composting process, ventilation and manual turning are carried out. The ventilation rate is controlled at 0.3-0.5 L / min / kg compost material, and ventilation is carried out for 25-35 minutes and stopped for 25-35 minutes. On the 28th to 32nd day of composting, polyphosphate-accumulating bacteria are inoculated. Turn the compost every 3 days from the 0th to 15th day. From the 16th to 45th day, the turning frequency is adjusted to once every 5 days. From the 46th to 60th day, the turning frequency is reduced to once every 10 days to obtain phosphorus-rich organic fertilizer.
[0010] It should be noted that the phosphate-solubilizing bacterium described in this invention is *Brevibacillus laterosporus* G-40, which was deposited at the China Center for Type Culture Collection (CCTCC) on June 30, 2017, at Wuhan University, China, with accession number CCTCC NO: M2017400; and the polyphosphate-accumulating bacterium is *Candida Tropicalis* G-94, which was deposited at the CCTCC on June 30, 2017, at Wuhan University, China, with accession number CCTCC NO: M2017402.
[0011] More preferably, in the method of producing phosphorus-rich organic fertilizer by composting phosphogypsum as described above, the mixing mass ratio of sawdust and livestock manure in step (1) is 1:(3-5).
[0012] More preferably, in the method for producing phosphorus-rich organic fertilizer by composting phosphogypsum as described above, the wood chips are sawdust, and the livestock and poultry manure is fresh chicken manure or pig manure.
[0013] More preferably, in the method for producing phosphorus-rich organic fertilizer by composting phosphogypsum as described above, the mass ratio of C / N in the mixture in step (1) is (20-30):1.
[0014] More preferably, in the method for producing phosphorus-rich organic fertilizer by composting phosphogypsum as described above, the amount of phosphogypsum added in step (2) accounts for 8 to 12% of the mass of the mixture.
[0015] More preferably, in the method for producing phosphorus-rich organic fertilizer from phosphogypsum compost as described above, step (3) involves adjusting the moisture content of the compost material to 55-65%.
[0016] More preferably, in the method for producing phosphorus-rich organic fertilizer from phosphogypsum compost as described above, the inoculation amount of phosphate-solubilizing bacteria or polyphosphate-accumulating bacteria in step (3) is not less than 5 × 10⁻⁶. 8 CFU / kg compost material.
[0017] Compared with the prior art, the method for producing phosphorus-rich organic fertilizer from phosphogypsum compost provided by the present invention has the following advantages and significant progress:
[0018] (1) Phosphorus enrichment treatment was carried out by adding phosphogypsum to livestock and poultry manure. At the same time, phosphorus-solubilizing bacteria were inoculated in the early stage of composting. The phosphorus-solubilizing bacteria can convert insoluble phosphorus into readily available phosphorus that can be absorbed by plants by secreting organic acids and phosphatases, thereby improving the fertilizer efficiency of compost. Subsequently, polyphosphate-accumulating bacteria were inoculated during the cooling period of composting, which is conducive to increasing the phosphorus content of microbial biomass, thereby reducing the fixation of phosphorus in the soil and further improving the phosphorus utilization efficiency.
[0019] (2) Under the combined treatment of adding phosphogypsum and inoculating with phosphate-solubilizing bacteria and polyphosphate-accumulating bacteria, the composition of the microbial community in the compost was significantly changed. The relative abundance of microorganisms related to phosphorus dissolution and transformation (such as Bacillus, Corynebacterium, Pseudogracilibacillus) and the abundance of genes related to organic phosphorus mineralization or inorganic phosphorus dissolution, such as phoD, mdh and maeA, were increased in high-phosphorus manure. This promoted the transformation of difficult-to-use phosphorus components and the phosphorus bioavailability of compost products.
[0020] (3) This invention will provide a scientific basis and technical support for the efficient treatment of livestock and poultry manure and phosphogypsum and the resource utilization of phosphorus, which is of great significance for promoting the resource utilization of agricultural waste, sustainable agricultural development and environmental protection. Detailed Implementation
[0021] The following examples further describe the implementation process and beneficial effects of the method of the present invention. These examples are for illustrative purposes only and do not limit the scope of protection of the present invention. Obvious modifications made by those skilled in the art based on the examples are also included within the scope of the present invention. The basic physicochemical properties of the raw materials used in the following examples and test cases are shown in Table 1.
[0022] Table 1 Basic Physicochemical Properties of Raw Materials
[0023]
[0024] Note: a: Calculated on a wet basis; b: Calculated on a dry basis.
[0025] Example 1: Production of Phosphorus-Enriched Organic Fertilizer
[0026] (1) Weigh 2 kg of sawdust and 8 kg of fresh chicken manure at a mass ratio of 1:4, mix them evenly to obtain a mixture. The mass ratio of C / N in the mixture is about 25:1.
[0027] (2) Add 1 kg of phosphogypsum to the mixture obtained in step (1), mix evenly to obtain compost material;
[0028] (3) Add the compost material obtained in step (1) into a closed reactor, adjust the moisture content to 60%, and then inoculate with Bacillus laterosporus G-40 for aerobic composting. The entire composting process lasts for 60 days. During the composting process, ventilation and manual turning are carried out. The ventilation rate is controlled at 0.4 L / min / kg compost material, and ventilation is stopped for 30 minutes and stopped for 30 minutes. On the 30th day of composting, Candida Tropicalis G-94 is inoculated. Turn the compost every 3 days from day 0 to 15. From day 16 to 45, the turning frequency is adjusted to once every 5 days. From day 46 to 60, the turning frequency is reduced to once every 10 days to obtain phosphorus-rich organic fertilizer.
[0029] When preparing phosphate-solubilizing or polyphosphate-accumulating bacteria inoculants, firstly, a small amount of frozen phosphate-solubilizing or polyphosphate-accumulating bacteria inoculum is picked up with a sterile toothpick and streaked onto LB solid medium for isolation. The inoculum is then activated by incubation at 37°C for 12 hours. Next, a single colony is picked up with an inoculation loop and placed in liquid LB medium, shaken at 180 rpm for 3 days. After incubation, the concentration of *Bacillus laterosporus* G-40 or *Candida tropicalis* G-94 is approximately 10. 9 CFU / mL. Before application, dilute the inoculum with sterile water to a concentration of 1.5 × 10⁻⁶ CFU / mL. 8 CFU / mL, inoculation dose is 5 mL / kg (wet weight ratio).
[0030] Comparative Example 1: Production of Phosphorus-Enriched Organic Fertilizer
[0031] (1) Weigh 2 kg of sawdust and 8 kg of fresh chicken manure at a mass ratio of 1:4, mix them evenly to obtain a mixture. The mass ratio of C / N in the mixture is about 25:1.
[0032] (2) Add the compost material obtained in step (1) into a closed reactor, adjust the moisture content to 60%, and then carry out aerobic composting. The entire composting process lasts for 60 days. During the composting process, ventilation and manual turning are carried out. The ventilation rate is controlled at 0.4 L / min / kg compost material, and ventilation is stopped for 30 minutes and stopped for 30 minutes. Turn the compost every 3 days from day 0 to 15. From day 16 to 45, the turning frequency is adjusted to once every 5 days. From day 46 to 60, the turning frequency is reduced to once every 10 days to obtain phosphorus-rich organic fertilizer.
[0033] Comparative Example 2: Production of Phosphorus-Enriched Organic Fertilizer
[0034] (1) Weigh 2 kg of sawdust and 8 kg of fresh chicken manure at a mass ratio of 1:4, mix them evenly to obtain a mixture. The mass ratio of C / N in the mixture is about 25:1.
[0035] (2) Add 1 kg of phosphogypsum to the mixture obtained in step (1), mix evenly to obtain compost material;
[0036] (3) Add the compost material obtained in step (1) into a closed reactor, adjust the moisture content to 60%, and then inoculate with Bacillus laterosporus G-40 (concentration of 1.5 × 10⁻⁶). 8 Aerobic composting was carried out using CFU / mL (inoculation dose of 5 mL / kg) over a period of 60 days. During the composting process, ventilation and manual turning were carried out. The ventilation rate was controlled at 0.4 L / min / kg of compost material, with ventilation lasting 30 minutes and stopping for 30 minutes. The compost was turned every 3 days from day 0 to 15. From day 16 to 45, the turning frequency was adjusted to once every 5 days. From day 46 to 60, the turning frequency was reduced to once every 10 days to obtain phosphorus-rich organic fertilizer.
[0037] Example 2: Study on the phosphorus availability of phosphorus-rich organic fertilizers obtained by different treatment methods
[0038] Treatment 1 (CK): Chicken manure and sawdust were mixed evenly at a mass ratio of 4:1 and composted. For specific methods, please refer to Comparative Example 1.
[0039] Treatment 2 (PSB): Chicken manure and sawdust were mixed evenly at a mass ratio of 4:1, and 10% phosphogypsum was added. The compost was then inoculated with Bacillus laterosporus G-40. For specific methods, please refer to Comparative Example 2.
[0040] Treatment 3 (PSB+POA): Chicken manure and sawdust were mixed evenly at a mass ratio of 4:1, and 10% phosphogypsum was added. At the beginning of composting, Bacillus laterosporus G-40 was inoculated, and Candida Tropicalis G-94 was inoculated during the cooling period of composting (30 days). For specific methods, please refer to Example 1.
[0041] The composting process lasted 60 days. Samples were collected at three different depths on days 0, 30, and 60, and then the samples were thoroughly mixed. Approximately 200 grams of sample were collected each time. The mixed sample was aliquoted into two portions: one portion (150g) was stored at 4°C for physicochemical analysis; the other portion (50g) was stored at -80°C for subsequent microbiological analysis.
[0042] Table 2. Phosphorus content in microbial biomass (mg / kg)
[0043]
[0044] Table 3 Available phosphorus content (g / kg)
[0045]
[0046] The data in Tables 2 and 3 show that inoculating the compost with the phosphate-solubilizing bacterium *Bacillus laterosporus* G-40 during the early stage of composting, combined with inoculating the polyphosphate-accumulating bacterium *Candida Tropicalis* G-94 during the cooling period, is beneficial for increasing the available phosphorus content of the compost. Inoculation and fermentation treatment with *Candida Tropicalis* G-94 is beneficial for increasing the phosphorus content of microbial biomass.
Claims
1. A method for producing phosphorus-rich organic fertilizer from phosphogypsum compost, characterized in that, The method includes the following steps: (1) Weigh out the sawdust and livestock manure in proportion, mix them evenly to obtain the mixture; (2) Add phosphogypsum to the mixture obtained in step (1) in proportion, mix evenly to obtain compost material; (3) Add the compost material obtained in step (1) into a closed reactor, adjust the moisture content, and then inoculate with phosphorus-solubilizing bacteria for aerobic composting. During the composting process, ventilation and manual turning are carried out. The ventilation rate is controlled at 0.3-0.5 L / min / kg compost material, and ventilation is carried out for 25-35 minutes and stopped for 25-35 minutes. On the 28th-32nd day of composting, polyphosphate-accumulating bacteria are inoculated. Turn the compost every 3 days from the 0th to the 15th day. From the 16th to the 45th day, the turning frequency is adjusted to once every 5 days. From the 46th to the 60th day, the turning frequency is reduced to once every 10 days to obtain phosphorus-rich organic fertilizer. The phosphate-solubilizing bacteria are Bacillus laterosporus G-40; the polyphosphate-accumulating bacteria are Candida Tropicalis G-94.
2. The method for producing phosphorus-rich organic fertilizer from phosphogypsum compost according to claim 1, characterized in that, In step (1), the mass ratio of wood chips and livestock manure is 1:(3-5).
3. The method for producing phosphorus-rich organic fertilizer from phosphogypsum compost according to claim 2, characterized in that, The wood chips are sawdust; the livestock and poultry manure is fresh chicken manure or pig manure.
4. The method for producing phosphorus-rich organic fertilizer from phosphogypsum compost according to claim 1, characterized in that, The mass ratio of C / N in the mixture in step (1) is (20-30):
1.
5. The method for producing phosphorus-rich organic fertilizer from phosphogypsum compost according to claim 1, characterized in that, The amount of phosphogypsum added in step (2) accounts for 8 to 12% of the mass of the mixture.
6. The method for producing phosphorus-rich organic fertilizer from phosphogypsum compost according to claim 1, characterized in that, In step (3), the moisture content of the compost material is adjusted to 55-65%.
7. The method for producing phosphorus-rich organic fertilizer from phosphogypsum compost according to claim 1, characterized in that, The inoculation amount of phosphate-solubilizing bacteria or polyphosphate-accumulating bacteria mentioned in step (3) shall not be less than 5 × 10⁻⁶. 8 CFU / kg compost material.