Feces full-amount resource recycling process

Abstract

The invention discloses a full-amount resource recycling process for livestock and poultry manure. The full-amount resource recycling process comprises three links of anaerobic fermentation, three-stage membrane separation and resource utilization. The method comprises the following steps: firstly, realizing efficient degradation of organic matters in feces through anaerobic fermentation and producing biogas; then, the biogas slurry is concentrated and separated step by step through a three-stage membrane separation technology, biogas residues, concentrated water and recyclable fresh water are obtained, the biogas residues can be processed and prepared into organic bacterial manure, the concentrated water is converted into high-nutrient water-soluble fertilizer, and the fresh water can be recycled. The produced biogas is used for power generation, and the obtained electric energy is further used for heating of an anaerobic fermentation tank and evaporation and drying of a concentrated solution, so that gradient utilization and internal self-circulation of energy are realized. Compared with a traditional excrement treatment mode, the method has the advantages that full-quantization, harmless and efficient resource utilization of the excrement is achieved, nitrogen, phosphorus, potassium and small-molecular-weight organic matter are reserved to the maximum extent, and the nutrient value and market competitiveness of the water-soluble fertilizer are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of manure resource utilization technology, specifically to a process for the full-volume resource recovery of manure. Background Technology

[0002] In recent years, with rapid economic development, animal husbandry is rapidly transforming from the traditional free-range, extensive model to a large-scale, intensive, and standardized approach. While this transformation has significantly improved breeding efficiency and productivity, it has also led to a sharp increase in livestock and poultry manure emissions. According to relevant statistics, by 2025, my country's annual livestock and poultry manure production will exceed 4 billion tons, containing 95.8% of chemical oxygen demand (COD) and 56.4% of nitrogen and phosphorus pollutants, respectively, posing a severe challenge to environmental safety and sustainable agricultural development.

[0003] The core contradiction in the treatment and utilization of livestock and poultry manure lies in the conflict between the environmental pressure brought about by high pollution loads and the insufficient efficiency of resource utilization. This contradiction is mainly manifested in the following aspects: 1) Environmental protection: Livestock and poultry manure is a typical wastewater with high COD and high ammonia nitrogen. If traditional discharge standards are met, the process is not only complex and costly, but also difficult to achieve economic feasibility and widespread application in large-scale farming scenarios.

[0004] 2) Resource Utilization: Currently, the resource utilization of manure mainly relies on returning it to the fields. However, the amount of manure generated by large-scale, intensive livestock farms far exceeds the absorption capacity of surrounding land. Due to limited land resources, manure cannot be completely disposed of locally and must be transported to other locations and centrally treated, thus increasing transportation and disposal costs and bringing the risk of secondary pollution. At the same time, some farms have not fully assessed the land's carrying capacity and have applied excessive amounts of manure, leading to the accumulation of nitrogen and phosphorus in the soil, inducing problems such as soil compaction and acidification, and potentially causing eutrophication of water bodies through runoff or seepage, posing a serious threat to the regional water environment and ecosystem.

[0005] 3) Engineering applications: Existing technologies mostly convert manure into liquid fertilizer, but there are technical and economic challenges in the storage, transportation, and long-distance distribution of liquid fertilizer, which restricts its widespread application. Although solid fertilizer can alleviate transportation pressure to some extent, its preparation process is energy-intensive and has poor nutrient stability, which can easily lead to a decline in fertilizer quality and affect the resource utilization effect.

[0006] In summary, existing approaches to livestock and poultry manure treatment and resource utilization all suffer from high environmental risks, low resource recovery efficiency, and poor economic applicability. Therefore, there is an urgent need to develop a comprehensive, harmless, and highly efficient livestock and poultry manure recycling process to overcome the bottlenecks of traditional models in environmental protection, resource recycling, and engineering applications. This would enable the reduction, stabilization, and high-value utilization of livestock and poultry manure, providing technical support for the green and sustainable development of animal husbandry. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a process for the complete resource recovery of fecal waste.

[0008] The technical solution of this invention is: a process for the complete resource recovery of fecal waste, comprising the following steps: S1, Anaerobic fermentation treatment The manure is pretreated to remove floating matter and solid particles, and the manure is preheated to 18~20℃. Then the manure is introduced into the CSTR anaerobic digester for mesophilic fermentation at a temperature of 30~40℃. The fermentation liquid produced by mesophilic fermentation is then separated into solid and liquid components to collect biogas, biogas slurry, and biogas residue. S2, Three-stage membrane treatment The biogas slurry collected in S1 is pretreated by nitrogen fixation-air flotation process to obtain pretreated biogas slurry with SS < 50 mg / L. Then, the pretreated biogas slurry is introduced into the membrane treatment system and subjected to primary concentration, primary separation, secondary separation, secondary concentration and tertiary concentration treatment in sequence to obtain organic sludge, concentrated water with salt content ≥ 80000 mg / L and fresh water with salt content ≤ 1000 mg / L. Regarding the nitrogen fixation-air flotation process, the SS (suspended solids) of the biogas slurry after S1 anaerobic fermentation is approximately 1-1.5% (mainly humic acid). Traditional processes use coagulation sedimentation followed by natural settling for pretreatment, but the results are unsatisfactory and can easily cause membrane clogging. By adjusting the pH of the biogas slurry to less than 5.5, it is possible to prevent ammonia nitrogen from escaping during air flotation and to quickly remove humic acid through simple filtration by utilizing the principle of humic acid precipitation. The filtered humic acid, combined with KOH to adjust the pH, can be compounded with soluble liquid fertilizer to prepare organic-inorganic compound fertilizer. S3, Resource Utilization S3-1, Utilization of concentrated water: The concentrated water obtained in S2 is evaporated and dried, and used to prepare solid water-soluble fertilizer according to fertilizer standards; S3-2, Utilization of biogas residue and organic sludge: Organic microbial fertilizer is prepared by using aerobic fermentation tank composting process to prepare biogas residue collected in S1 and organic sludge obtained in S2. S3-3, Utilization of biogas: The biogas collected in S1 is fed into the biogas purification system (desulfurization tower, dehydration tank) for treatment. After meeting the requirements of the generator set, it is temporarily stored in the tank and used to power the power systems of each process link of the generator set. The heat energy generated by the generator set is also recovered. Part of the heat energy is used to raise the temperature of the anaerobic digester, and the other part is used for the evaporation and drying of the concentrated water. S3-4. Utilization of fresh water: The fresh water obtained in S2 is mixed with the evaporated water from S3-1 and then treated by an end-of-pipe water treatment system, and then recycled.

[0009] Furthermore, the pretreatment includes using mechanical bar screens and a desanding tank to remove floating matter and solid particles from the sewage.

[0010] Explanation: Mechanical bar screens have high separation efficiency and can intercept floating impurities in sewage with an interception rate of over 90%, significantly reducing the load on subsequent treatment and being easy to maintain; while sand removal tanks can effectively remove sand particles with a diameter >2mm, with a removal rate of over 70%. The combination of mechanical bar screens and sand removal tanks can effectively remove floating matter and solid particles from sewage for subsequent processes.

[0011] Furthermore, it also includes: collecting the odor generated during the pretreatment in S2 and the odor generated during the resource utilization in S3, and centrally treating the collected odor using a biological deodorization method.

[0012] Description: This method utilizes a biological deodorization process to treat collected odorous gases. All structures and equipment in the wastewater treatment and resource utilization systems that generate odors are covered. After being drawn in under negative pressure, the odorous gases are centrally treated using a biological deodorization method, ensuring that the exhaust gas is harmless after deodorization. Spraying increases the humidity of the odorous gases and adjusts the temperature. The humidified and temperature-controlled odors adhere to microorganisms on the biological packing material, which, through metabolism, degrade them into carbon dioxide, water, and other harmless or low-harm substances. This method has high purification efficiency, requires no complex equipment, does not produce secondary pollution, and leaves no chemical residues. Relying on natural microbial degradation, it is more environmentally friendly.

[0013] Furthermore, in S3-4, the method of using a point-of-use water treatment system is as follows: removing SS, COD, ammonia nitrogen, and total nitrogen from fresh water and evaporated water, and disinfecting and sterilizing the fresh water and evaporated water.

[0014] Explanation: By passing the water treated by the membrane and evaporated into the intermediate water tank, if the effluent does not meet the reinjection standards, it can be passed into the end-of-pipe water treatment system, such as the buffer equalization tank, denitrification tank, BIOROTOR-C, disinfection booster tank, etc., to remove SS, COD, ammonia nitrogen, total nitrogen, etc., so that it can be safely applied to farmland.

[0015] Further, in S2, the membrane treatment system includes a primary concentration unit, a primary separation unit, a secondary separation unit, a secondary concentration unit, and a tertiary concentration unit, and the treatment method is as follows: 1) The pretreated biogas slurry is introduced into the primary thickening unit to intercept and remove impurities and suspended solids in the pretreated biogas slurry, resulting in preliminary sludge and primary concentrated permeate. The primary concentrated permeate is introduced into the primary separation unit to remove residual suspended solids, resulting in primary separated permeate and primary separated sludge. The primary separated sludge and the preliminary sludge are mixed to form organic sludge. 2) The primary separation permeate is introduced into the secondary separation unit to separate the high-value nitrogen, phosphorus, potassium and small molecule organic matter from the primary separation permeate, resulting in secondary separation permeate and secondary separation concentrate; 3) The secondary separation permeate is introduced into the secondary concentration unit to further separate the remaining high-value nitrogen, phosphorus, potassium and small molecule organic matter in the secondary separation permeate, to obtain secondary concentrated permeate and secondary concentrated concentrate. The secondary separation concentrate and secondary concentrated concentrate are then introduced into the tertiary concentration unit to obtain tertiary concentrated permeate and tertiary concentrated concentrate. 4) Collect the tertiary concentrate, which yields concentrate with a salt content ≥80000mg / L. Collect the secondary and tertiary concentrates, which yield freshwater with a salt content ≤1000mg / L.

[0016] Explanation: The process involves primary concentration in a first-stage concentration unit, such as a rapid filter, multi-media filter, or ultrafiltration system, to remove suspended solids and other solids from the water. Raw water enters the primary concentration unit, and the concentrated wastewater, meeting standards, is discharged into the wastewater tank. A large amount of suspended solids is retained and discharged along with the concentrate into the downstream concentrate tank. A primary separation unit, such as a mechanically stirred clarifier, triplet tank, or resin softening system, removes suspended solids and selectively reduces unwanted salt content in some products. A secondary separation unit, such as a nanofiltration membrane, resin bed, or electrostatic desalination system, extracts high-value ions from the water, further purifying the biogas slurry while extracting some high-value nutrients. The process continues with a secondary concentration unit... The system undergoes secondary concentration treatment, such as membrane treatment, EDI, and extraction processes, to further purify nutrients and clean the water, meeting the requirements for high-concentration brine (salt content ≥10000mg / L). A tertiary concentration unit, using processes such as STRO, DTRO, and EDR, further concentrates and reduces the volume of the secondary concentrate and secondary separation concentrate (i.e., the influent to the tertiary concentration unit is a mixture of the concentrates from the secondary concentration and separation units). This reduces investment and operating costs for downstream evaporation and crystallization equipment, ultimately achieving a salt content of ≤1000mg / L in the freshwater and ≥80000mg / L in the concentrated water after membrane treatment, meeting the process requirements for full-scale resource recovery.

[0017] Furthermore, the method for preparing the organic microbial fertilizer is as follows: 1) The biogas residue collected by S1 and the organic sludge obtained by the S2 membrane treatment system are mixed in a sludge conditioning tank to obtain organic microbial fertilizer raw materials. The organic microbial fertilizer raw materials are processed by a high-pressure plate and frame filter press until the moisture content reaches below 70%. Then, the moisture content is controlled at 30~65% by adding dry materials, product return, heat drying and sun drying. After that, a closed high-temperature aerobic fermentation process is adopted, and the fermentation temperature is controlled at 70~100℃, and the high temperature of 70~100℃ is maintained for more than 5~7 days. 2) During the closed-loop high-temperature aerobic fermentation process, high-carbon materials are added to the organic microbial fertilizer raw materials to adjust the C / N ratio of aerobic fermentation to 25~35:1; the pH value of aerobic fermentation is adjusted to 6~8 using a regulator. The high-carbon materials are one of sawdust, straw powder, and fallen leaves, and the regulator is one of CaCO3, lime, and gypsum.

[0018] Explanation: Since anaerobic fermentation cannot decompose all organic matter into small molecules such as methane, carbon dioxide, water, acetic acid, and propionic acid, a certain amount of solids still remain in the biogas slurry. Aerobic fermentation can kill pathogens and insect eggs, and at the same time, it can aerobically decompose organic matter that cannot be decomposed by anaerobic fermentation. Organic fertilizer can also be obtained through this treatment, thereby achieving the harmless treatment and fertilizer utilization of livestock and poultry manure.

[0019] Furthermore, in S3-1, the evaporation adopts a heat pump low-temperature evaporation, and the drying adopts a drum scraper dryer and a flash dryer.

[0020] Note: Since the water-soluble fertilizer cannot be denatured during evaporation and concentration, and is a heat-sensitive material, it is produced into a dry powder by using a heat pump for low-temperature evaporation and employing a drum scraper dryer and a flash dryer. This reduces nitrogen loss and improves the quality of the solid water-soluble fertilizer.

[0021] The beneficial effects of this invention are: Compared with traditional manure treatment methods, such as the traditional environmentally friendly method of solid-liquid separation followed by solid-to-fertilizer production and liquid-to-liquid treatment and discharge, this invention does not fully utilize the nitrogen resources in manure, easily leading to resource waste. Furthermore, to meet nitrogen emission standards, the aerobic digestion process requires additional carbon sources due to the high nitrogen content, and the pH fluctuations during the conversion of nitrate nitrogen to ammonia nitrogen necessitate the addition of NaOH to maintain system balance. The traditional resource-based treatment method of directly returning the biogas slurry produced from anaerobic fermentation of manure to the fields results in biogas slurry production far exceeding farmland needs. Farmland demand is greatly affected by seasonal fluctuations, while biogas slurry production remains relatively constant, posing a problem for transporting excess biogas slurry. In contrast, this invention achieves full-scale, harmless, and highly efficient resource utilization of manure, maximizing the retention of nitrogen, phosphorus, potassium, and small-molecule organic matter, significantly improving the nutrient value and market competitiveness of water-soluble fertilizers. Meanwhile, the process of this invention effectively solves industry problems such as high manure treatment costs, insufficient resource utilization, and heavy land carrying capacity, and provides a green and sustainable technical path for the transformation of livestock and poultry farming from extensive to large-scale, intensive, and standardized operations, with good prospects for industrial promotion and application. Specifically, it is as follows: The heat generated by biogas is recycled to the anaerobic digester for heating and the concentrated water for evaporation and drying, and the electricity generated is recycled to the various power systems in the process. By utilizing biogas residue to produce organic microbial fertilizer and biogas slurry (concentrated water) to produce solid water-soluble fertilizer, the high-value nitrogen, phosphorus, potassium and small-molecule organic matter in the water can be retained to the greatest extent, thereby producing higher-quality water-soluble fertilizer products; at the same time, it solves the transportation problem of liquid water-soluble fertilizers prepared by traditional resource utilization methods.

[0022] By utilizing biogas slurry (freshwater), it can be treated and reused, or directly discharged in compliance with standards. This achieves comprehensive resource recovery in the entire process of full resource recovery of manure and sewage. Moreover, the overall process is energy-saving and environmentally friendly, and has great potential for large-scale development.

[0023] Meanwhile, the process of this invention maximizes biogas production by directly fermenting manure without solid-liquid separation. This biogas can then be used for power generation or direct heating, solving the problem of high energy consumption required in fertilizer concentration. Furthermore, the self-production and self-sale of biogas avoids transportation costs. It also lays the foundation for membrane separation and concentration processes to produce high-quality water-soluble fertilizers. This invention effectively solves industry problems such as high manure treatment costs, insufficient resource utilization, and heavy land burden. It provides a green and sustainable technological path for the transformation of livestock and poultry farming from extensive to large-scale, intensive, and standardized operations, and has promising prospects for industrial promotion and application. Attached Figure Description

[0024] Figure 1 This is a process roadmap for the complete resource recovery of fecal waste according to the present invention. Detailed Implementation

[0025] The present invention will now be described in more detail with reference to specific embodiments, so as to better demonstrate the advantages of the present invention.

[0026] Example 1: A process for the complete resource recovery of fecal waste, comprising the following steps: S1, Anaerobic fermentation treatment The manure is pretreated to remove floating matter and solid particles. The water quality and quantity are then adjusted as needed according to the mesophilic fermentation process conditions. The manure is preheated to 20°C and then introduced into the CSTR anaerobic digester for mesophilic fermentation at 38°C. The fermentation liquid produced by the mesophilic fermentation is then separated into solid and liquid components to collect biogas, biogas slurry, and biogas residue. The pretreatment includes using mechanical bar screens and sand removal tanks to remove floating objects and solid particles from the sewage. The mechanical bar screens can intercept floating impurities in the sewage with an interception rate of over 90%, significantly reducing the load on subsequent treatment. The sand removal tanks can effectively remove sand particles with a diameter >2mm, with a removal rate of over 70%. S2, Three-stage membrane treatment The biogas slurry collected in S1 is pretreated using a nitrogen fixation-air flotation process to obtain pretreated biogas slurry with SS < 50 mg / L. The pretreated biogas slurry is then introduced into a membrane treatment system for sequential primary concentration, primary separation, secondary separation, secondary concentration, and tertiary concentration treatment. Specifically, the membrane treatment system includes a primary concentration unit, a primary separation unit, a secondary separation unit, a secondary concentration unit, and a tertiary concentration unit. The treatment method is as follows: 1) The pretreated biogas slurry is introduced into the primary thickening unit to intercept and remove impurities and suspended solids in the pretreated biogas slurry, resulting in preliminary sludge and primary concentrated permeate. The primary concentrated permeate is introduced into the primary separation unit to remove residual suspended solids, resulting in primary separated permeate and primary separated sludge. The primary separated sludge and the preliminary sludge are mixed to form organic sludge. 2) The primary separation permeate is introduced into the secondary separation unit to separate the high-value nitrogen, phosphorus, potassium and small molecule organic matter from the primary separation permeate, resulting in secondary separation permeate and secondary separation concentrate; 3) The secondary separation permeate is introduced into the secondary concentration unit to further separate the remaining high-value nitrogen, phosphorus, potassium and small molecule organic matter in the secondary separation permeate, to obtain secondary concentrated permeate and secondary concentrated concentrate. The secondary separation concentrate and secondary concentrated concentrate are then introduced into the tertiary concentration unit to obtain tertiary concentrated permeate and tertiary concentrated concentrate. 4) Collect the tertiary concentrate, which yields concentrate with a salt content ≥80000mg / L; collect the secondary and tertiary concentrates, which yield freshwater with a salt content ≤1000mg / L. Regarding the nitrogen fixation-air flotation process, the SS (suspended solids) of the biogas slurry after S1 anaerobic fermentation is approximately 1-1.5% (mainly humic acid). Traditional processes use coagulation sedimentation followed by natural settling for pretreatment, but the results are unsatisfactory and prone to membrane clogging. By adjusting the pH of the biogas slurry to 4 before the nitrogen fixation-air flotation process, it is possible to prevent ammonia nitrogen from escaping during the air flotation process. On the other hand, the humic acid is quickly removed by simple filtration using the principle of humic acid precipitation. The filtered humic acid, combined with KOH to adjust the pH, can be compounded with soluble liquid fertilizer to prepare organic-inorganic compound fertilizer.

[0027] Regarding the three-stage membrane treatment, the primary concentration unit (such as commercially available rapid filter, multi-media filter, or ultrafiltration system) removes suspended solids and other solids from the water. Raw water enters the primary concentration unit, and the concentrated water, meeting standards, is discharged into the product water tank. A large amount of suspended solids retained are discharged along with the concentrate into the downstream concentrate tank, used to remove most of the suspended impurities in the biogas slurry. The organic sludge generated by the primary concentration unit is utilized for resource recovery. The primary concentrated product water enters the primary separation unit (such as commercially available mechanically stirred clarifiers, triple tanks, or resin softeners) to remove suspended solids and selectively reduce unwanted salt content in some products. The secondary separation unit (such as commercially available nanofiltration membranes, resin beds, or electrostatic desalination) extracts high-value ions from the water, further refining the biogas slurry while extracting some high-value nutrients. (Purification) Removes residual hardness and suspended solids from the water; high-value nitrogen, phosphorus, potassium, and small-molecule organic matter are separated from the water through a secondary separation unit. The secondary separation product water enters a secondary concentration unit (such as membrane treatment, EDI, or extraction processes) to further purify nutrients and improve water quality, meeting the requirements for high-concentration brine (salt content ≥10000mg / L). The remaining high-value nitrogen, phosphorus, potassium, and small-molecule organic matter in the water are separated again. The secondary separation concentrate and the secondary concentration concentrate enter a tertiary concentration unit (such as STRO, DTRO, or EDR treatment processes) to further concentrate and reduce the volume of the secondary concentration concentrate and the secondary separation concentrate (i.e., the influent to the tertiary concentration unit is a mixture of the concentrates produced by the secondary concentration unit and the secondary separation unit), thereby reducing the investment and operating costs of downstream evaporation and crystallization equipment.

[0028] S3, Resource Utilization S3-1, Utilization of concentrated water: The concentrated water obtained in S2 is evaporated and dried to prepare solid water-soluble fertilizer according to fertilizer standards. The evaporation is carried out by heat pump low-temperature evaporation, and the drying is carried out by commercially available drum scraper dryer and flash dryer. S3-2, Utilization of biogas residue and organic sludge: Organic microbial fertilizer is prepared by using aerobic fermentation tank composting process to prepare biogas residue collected in S1 and organic sludge obtained in S2. The preparation method of organic microbial fertilizer is as follows: 1) The biogas residue collected in S1 and the organic sludge obtained in S2 are mixed in a sludge conditioning tank to obtain organic microbial fertilizer raw materials. The organic microbial fertilizer raw materials are processed to a moisture content of 69% by a high-pressure plate and frame filter press. Then, the moisture content is controlled at 45% by adding dry materials, returning the finished product, heat drying, and sun drying. After that, a closed high-temperature aerobic fermentation process is adopted, and the fermentation temperature is controlled at 90℃ and maintained at 90℃ for 7 days. 2) During the closed-loop high-temperature aerobic fermentation process, high-carbon materials are added to the organic microbial fertilizer raw materials to adjust the C / N ratio of aerobic fermentation to 30:1; the pH value of aerobic fermentation is adjusted to 6-8 using a regulator, wherein the high-carbon material is sawdust and the regulator is CaCO3.

[0029] S3-3. Utilization of biogas: The biogas collected in S1 is fed into a biogas purification system (which includes commercially available desulfurization towers and dehydration tanks) for treatment. After the biogas meets the requirements of the generator set, it is temporarily stored in a tank for use by the generator set to supply power to the electrical systems of each process stage. The heat energy generated by the generator set is also recovered. Part of the heat energy is used to heat up the anaerobic digester, and the other part is used for the evaporation and drying of the concentrated water.

[0030] S3-4. Freshwater Utilization: The freshwater obtained in S2 and the evaporated water from S3-1 are tested to see if they meet the discharge standards. If they still exceed the discharge standards, the freshwater obtained in S2 and the evaporated water from S3-1 are mixed and treated using a point-of-use water treatment system. The treated water is then recycled. The method of using the point-of-use water treatment system is to remove SS, COD, ammonia nitrogen, and total nitrogen from the freshwater and evaporated water, and to disinfect and sterilize the freshwater and evaporated water. For example, the water from membrane treatment and evaporation can be introduced into an intermediate water tank. If the effluent does not meet the reinjection standards, it can be introduced into a point-of-use water treatment system, such as a commercially available buffer conditioning tank, denitrification tank, BIOROTOR-C, or disinfection booster tank, to remove SS, COD, ammonia nitrogen, and total nitrogen, making it safe for use in farmland.

[0031] Odor Treatment: The odor generated during the pretreatment in S2 and the odor generated during the resource utilization in S3 are collected by negative pressure suction. The collected odor is then centrally treated using a biological deodorization method to ensure that the exhaust gas is harmless after deodorization. Spraying increases the humidity of the odor and adjusts the temperature. The odor after humidification and temperature adjustment adheres to the microorganisms on the biological packing material. Under the action of metabolism, the odor is degraded into carbon dioxide, water and other harmless / low-harm substances, ensuring that the exhaust gas is harmless before being discharged.

[0032] Example 2: This example differs from Example 1 in that the parameters for mesophilic fermentation are different. The manure is preheated to 18°C, and the fermentation temperature for mesophilic fermentation is 30°C.

[0033] Example 3: This example differs from Example 1 in that the parameters for mesophilic fermentation are different. The manure is preheated to 19°C, and the fermentation temperature for mesophilic fermentation is 40°C.

[0034] Example 4: The difference between this example and Example 1 is the nitrogen fixation-air flotation process. The biogas slurry is adjusted to pH=3 before being treated by the nitrogen fixation-air flotation process.

[0035] Example 5: The difference between this example and Example 1 is the nitrogen fixation-air flotation process. The biogas slurry is adjusted to pH=5 before being treated by the nitrogen fixation-air flotation process.

[0036] Example 6: The difference between this example and Example 1 is that the preparation method parameters of the organic microbial fertilizer are different. The biogas residue collected in S1 and the organic sludge obtained in S2 are mixed in a sludge conditioning tank and pretreated by a high-pressure plate and frame filter press until the moisture content reaches 69%. The moisture content is controlled at 30% by adding dry materials, returning the finished product, heat drying and sun drying.

[0037] Example 7: The difference between this example and Example 1 is that the preparation method parameters of the organic microbial fertilizer are different. The biogas residue collected in S1 and the organic sludge obtained in S2 are mixed in a sludge conditioning tank and pretreated by a high-pressure plate and frame filter press until the moisture content reaches 69%. The moisture content is controlled at 65% by adding dry materials, returning the finished product, heat drying and sun drying.

[0038] Example 8: This example differs from Example 1 in that the preparation parameters of the organic microbial fertilizer are different. A closed high-temperature aerobic fermentation process is adopted, and the fermentation temperature is controlled at 70°C and maintained at 70°C for 5 days. At the same time, a high carbon content material is added to the raw materials to adjust the C / N ratio of aerobic fermentation to 25:1. The high carbon content material is straw powder. A regulator is used to adjust the pH value of aerobic fermentation to 6. The regulator is lime.

[0039] Example 9: This example differs from Example 1 in that the preparation parameters of the organic microbial fertilizer are different. A closed high-temperature aerobic fermentation process is adopted, and the fermentation temperature is controlled at 100℃ and maintained at 100℃ for 6 days. At the same time, a high carbon content material is added to the raw materials to adjust the C / N ratio of aerobic fermentation to 35:1. The high carbon content material is fallen leaves. A regulator is used to adjust the pH value of aerobic fermentation to 7. The regulator is gypsum.

[0040] Experimental Example: To test the quality difference between the water-soluble fertilizer produced by the process of this invention and existing water-soluble fertilizers, the following experiment was designed: 1. Design Principles: Except for the quality of water-soluble fertilizer, all other conditions (light, temperature, and moisture) should be kept consistent. Each group should contain 10 samples and the experiment should be repeated 3 times. A blank control group without fertilizer and a standard fertilized group should be set up as references, as detailed below: • Blank control group: watered only with plain water; • Standard fertilization group: Use commercially available water-soluble fertilizer that meets the NY1107-2006 standard; • The water-soluble fertilizer group to be tested: The water-soluble fertilizer prepared in Example 1 was used; Note: The concentration of water-soluble fertilizer in both the "standard fertilizer group" and the "water-soluble fertilizer group to be tested" is 75%.

[0041] 2. Selection of test plants: Based on the characteristics of water-soluble fertilizer, cherry tomato "Millennium" (seedling age 20 days) was selected.

[0042] 3. Selection of cultivation substrate: coconut coir: perlite = 3:1, pH = 5.8~6.2.

[0043] 4. Fertilization plan: Fertilizers were applied to each group of test plants using foliar spraying and root irrigation, as detailed below: • Foliar spraying: Dilute the water-soluble fertilizer 300 times and apply it once every 7 days for a total of 3 times; • Root watering: 3 times a week.

[0044] 5. Environmental control: Environmental control was implemented for each group of tested plants, including light, temperature, humidity, and watering, as detailed below: • Sunlight: 12 hours per day; Temperature: 25±2℃; Humidity: 60~70%; • Watering: Keep the growing medium moist but not too wet.

[0045] 6. Data Collection: The plant height of the "Millennium" cherry tomatoes in each group was measured regularly, and the plant height measurement data were statistically analyzed. The results are shown in the table below:

[0046] The results in the table above show that the plant height of the tested water-soluble fertilizer group was significantly higher, and the final yield was much higher than that of the standard fertilization group. The yield per plant of the cherry tomato "Millennium" increased by 18.9%. This demonstrates that the water-soluble fertilizer produced using this process has better planting effects, as it retains nitrogen, phosphorus, potassium, and small molecule organic matter in livestock and poultry manure to the maximum extent, thereby significantly improving the nutrient value and market competitiveness of the water-soluble fertilizer.

Claims

1. A process for the complete resource recovery of fecal waste, characterized in that, Includes the following steps: S1, Anaerobic fermentation treatment The manure is pretreated to remove floating matter and solid particles, and the manure is preheated to 18~20℃. Then the manure is introduced into the CSTR anaerobic digester for mesophilic fermentation at a temperature of 30~40℃. The fermentation liquid produced by mesophilic fermentation is then separated into solid and liquid components to collect biogas, biogas slurry, and biogas residue. S2, Three-stage membrane treatment The biogas slurry collected in S1 is pretreated by nitrogen fixation-air flotation process to obtain pretreated biogas slurry with SS < 50 mg / L. Then, the pretreated biogas slurry is introduced into the membrane treatment system and subjected to primary concentration, primary separation, secondary separation, secondary concentration and tertiary concentration treatment in sequence to obtain organic sludge, concentrated water with salt content ≥ 80000 mg / L and fresh water with salt content ≤ 1000 mg / L. S3, Resource Utilization S3-1, Utilization of concentrated water: The concentrated water obtained in S2 is evaporated and dried, and used to prepare solid water-soluble fertilizer according to fertilizer standards; S3-2, Utilization of biogas residue and organic sludge: Organic microbial fertilizer is prepared by using aerobic fermentation tank composting process to prepare biogas residue collected in S1 and organic sludge obtained in S2. S3-3. Utilization of biogas: The biogas collected in S1 is processed by the biogas purification system and then temporarily stored in a tank. It is used to power the power systems of each process step by the generator set, and the heat energy generated by the generator set is recovered. Part of the heat energy is used to heat up the anaerobic digester, and the other part of the heat energy is used for the evaporation and drying of the concentrated water. S3-4. Utilization of fresh water: The fresh water obtained in S2 is mixed with the evaporated water from S3-1 and then treated by an end-of-pipe water treatment system, and then recycled.

2. The process for full resource recovery of fecal waste according to claim 1, characterized in that, The pretreatment includes using mechanical bar screens and desanding tanks to remove floating matter and solid particles from the sewage.

3. The process for full resource recovery of fecal waste according to claim 1, characterized in that, Also includes: The odor generated during the pretreatment in S2 and the odor generated during the resource utilization in S3 are collected and centrally treated using a biological deodorization method.

4. The process for full resource recovery of fecal waste according to claim 1, characterized in that, In S3-4, the method of using a terminal water treatment system is to remove SS, COD, ammonia nitrogen, and total nitrogen from fresh water and evaporated water, and to disinfect and sterilize the fresh water and evaporated water.

5. The process for full resource recovery of fecal waste according to claim 1, characterized in that, In S2, the pretreated biogas slurry is introduced into a membrane treatment system for sequential primary concentration, primary separation, secondary separation, secondary concentration, and tertiary concentration. The membrane treatment system includes a primary concentration unit, a primary separation unit, a secondary separation unit, a secondary concentration unit, and a tertiary concentration unit. The treatment method is as follows: 1) The pretreated biogas slurry is introduced into the primary thickening unit to intercept and remove impurities and suspended solids in the pretreated biogas slurry, resulting in preliminary sludge and primary concentrated permeate. The primary concentrated permeate is introduced into the primary separation unit to remove residual suspended solids, resulting in primary separated permeate and primary separated sludge. The primary separated sludge and the preliminary sludge are mixed to form organic sludge. 2) The primary separation permeate is introduced into the secondary separation unit to separate the high-value nitrogen, phosphorus, potassium and small molecule organic matter from the primary separation permeate, resulting in secondary separation permeate and secondary separation concentrate; 3) The secondary separation permeate is introduced into the secondary concentration unit to further separate the remaining high-value nitrogen, phosphorus, potassium and small molecule organic matter in the secondary separation permeate, to obtain secondary concentrated permeate and secondary concentrated concentrate. The secondary separation concentrate and secondary concentrated concentrate are then introduced into the tertiary concentration unit to obtain tertiary concentrated permeate and tertiary concentrated concentrate. 4) Collect the tertiary concentrate, which yields concentrate with a salt content ≥80000mg / L. Collect the secondary and tertiary concentrates, which yield freshwater with a salt content ≤1000mg / L.

6. The process for full resource recovery of fecal waste according to claim 1, characterized in that, The method for preparing the organic microbial fertilizer is as follows: 1) The biogas residue collected by S1 and the organic sludge obtained by the S2 membrane treatment system are mixed in a sludge conditioning tank to obtain organic microbial fertilizer raw materials. The organic microbial fertilizer raw materials are processed by a high-pressure plate and frame filter press until the moisture content reaches below 70%. Then, the moisture content is controlled at 30~65% by adding dry materials, product return, heat drying and sun drying. After that, a closed high-temperature aerobic fermentation process is adopted, and the fermentation temperature is controlled at 70~100℃, and the high temperature of 70~100℃ is maintained for more than 5~7 days. 2) During the closed-loop high-temperature aerobic fermentation process, high-carbon materials are added to the organic microbial fertilizer raw materials to adjust the C / N ratio of aerobic fermentation to 25~35:1; the pH value of aerobic fermentation is adjusted to 6~8 using a regulator. The high-carbon materials are one of sawdust, straw powder, and fallen leaves, and the regulator is one of CaCO3, lime, and gypsum.

7. The process for full resource recovery of fecal waste according to claim 1, characterized in that, In S3-1, the evaporation is carried out using a heat pump for low-temperature evaporation, and the drying is carried out using a drum scraper dryer and a flash dryer.

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