Aerobic fermentation tank sludge treatment method

Abstract

The application discloses an aerobic fermentation tank sludge treatment method, and belongs to the technical field of sludge treatment. The method comprises the following steps: S1, raw material pretreatment: mixing dewatered sludge with a water content of 70-85% with auxiliary materials, adjusting the water content to 50-65% and the carbon-nitrogen ratio to 20-30:1, and crushing and uniformly mixing; S2, aerobic fermentation: feeding the pretreated material into an aerobic fermentation tank, monitoring the material temperature in real time through a multi-point temperature sensor, controlling the fermentation temperature at 55-65 DEG C through an intelligent temperature control system, and performing three-dimensional circulating stirring on the material through a stirring device during a fermentation period of 7-15 days, and dynamically adjusting the ventilation volume through a variable frequency fan according to the fermentation stage; and S3, post-treatment: screening and cooling the fermentation product, removing impurities, and obtaining an organic fertilizer product. Through the synergistic control of intelligent temperature control, three-dimensional stirring and dynamic ventilation, the application realizes accurate regulation and control of the fermentation process, has a short fermentation period, high treatment efficiency, reduces the sludge volume by 60-70%, reduces the water content of the product to below 30%, and can be used as a high-quality organic fertilizer resource, thereby having remarkable environmental and economic benefits.

Description

Technical Field

[0001] This invention relates to the field of sludge treatment technology, specifically to an aerobic fermentation tank sludge treatment method, which is particularly suitable for the harmless treatment and resource utilization of organic wastes such as municipal sludge, livestock manure, kitchen waste, and agricultural waste. Background Technology

[0002] With the continuous acceleration of urbanization and the sustained improvement of sewage treatment rates in my country, sludge production has been increasing year by year. Currently, my country's annual sludge production has exceeded 60 million tons (based on a moisture content of 80%). Sludge in sewage treatment mainly comes from primary sedimentation tanks, secondary sedimentation tanks, and advanced treatment processes. After mechanical dewatering, the moisture content of the sludge is typically 60%–85%, still presenting problems of high moisture content and large volume, which is detrimental to downstream disposal and resource utilization. Currently, the principles of sludge disposal in China are mainly "reduction, stabilization, harmlessness, and resource recovery."

[0003] In existing technologies, municipal sewage sludge, after mechanical dewatering, is typically treated and disposed of using processes such as sanitary landfill, sludge incineration, anaerobic digestion, and aerobic fermentation. However, these disposal methods all have varying degrees of drawbacks: Sanitary landfills typically require significant land resources, and the process generates leachate and methane gas. Leachate is a highly polluting liquid that contaminates the surrounding land and groundwater, while methane gas poses a risk of explosion and combustion if not properly managed. With increasingly stringent environmental regulations, landfilling is being banned in more and more regions.

[0004] Sludge incineration is a relatively thorough disposal method with significant volume reduction, but the equipment investment and operating costs are relatively high, and there is a risk of secondary air pollution, such as the emission of harmful gases like dioxins. At the same time, my country's sludge has low organic matter and high water content, resulting in high incineration costs and a lack of technical standards.

[0005] Anaerobic digestion technology has the advantages of energy recovery and environmental protection, but its investment and operating costs are high, and it requires a high organic content in the sludge.

[0006] Aerobic fermentation (also known as aerobic composting) is a process that utilizes aerobic thermophilic bacteria to decompose organic matter in sludge, forming humus. The fermentation products can be reused as fertilizer, making it a comprehensive treatment technology for achieving sludge harmlessness, volume reduction, stabilization, and resource utilization. However, existing aerobic fermentation technologies still face many problems that urgently need to be solved: First, the fermentation cycle is long and requires a large area. Traditional aerobic fermentation usually uses windrow or trough composting, requiring sludge to be spread out over a large area, resulting in low land utilization. The problem of insufficient processing capacity is particularly prominent due to the low temperatures in winter.

[0007] Second, the operation is highly manual and lacks automation. Most existing small-scale aerobic composting studies are conducted through direct stacking and manual turning. Manual turning easily leads to heat loss in the pile, affecting the aerobic composting process. At the same time, pile temperature monitoring mostly relies on taking average values ​​at regular intervals with thermometers, which cannot achieve real-time monitoring and makes it difficult to provide timely feedback on the effectiveness of ventilation volume and turning frequency.

[0008] Third, oxygen supply and ventilation control are rudimentary. The ventilation volume and frequency of forced oxygen supply cannot be automatically controlled. During fermentation, the sludge pile gradually compacts due to gravity, leading to poorer and uneven aeration from the aeration device, thus affecting the fermentation effect and prolonging the fermentation cycle.

[0009] Fourth, the equipment has low integration and high energy consumption. Existing aerobic fermentation equipment often separates functions such as stirring, ventilation, and temperature control, resulting in low system integration, large equipment footprint, high operating energy consumption, and high maintenance costs.

[0010] In conclusion, developing an aerobic fermenter sludge treatment method with a short fermentation cycle, small footprint, high degree of automation, low energy consumption, and stable treatment effect has significant practical significance and application value. Summary of the Invention

[0011] Therefore, addressing the technical problems of existing aerobic fermentation sludge treatment methods, such as long fermentation cycles, large land area requirements, extensive manual operation, low automation, crude oxygen supply control, and high energy consumption, this invention provides an aerobic fermentation tank sludge treatment method, aiming to achieve high efficiency, intelligent operation, volume reduction, and resource recovery in sludge treatment. A method for treating sludge from an aerobic fermenter, characterized by comprising the following steps: S1: Raw material pretreatment: Dewatered sludge with a moisture content of 70%~85% is mixed with auxiliary materials in a certain proportion, the moisture content of the materials is adjusted to 50%~65% and the carbon-nitrogen ratio is adjusted to 20~30:1, and then crushed and mixed evenly to obtain pretreated materials; S2: Aerobic fermentation: The pretreated material is fed into an aerobic fermentation tank and aerobic fermentation is carried out under oxygen supply conditions. During the fermentation process, the material temperature is monitored in real time by multiple temperature sensors, and the fermentation temperature is controlled at 55~65℃ by an intelligent temperature control system. The fermentation cycle is 7~15 days, and the fermentation product is obtained. S3: Post-processing: The fermentation product is screened and cooled to remove impurities and obtain organic fertilizer product; In the aerobic fermentation process, the material is stirred in a three-dimensional circulation using a stirring device, and the ventilation volume is dynamically adjusted by a variable frequency fan according to the fermentation stage to provide oxygen for microbial metabolism.

[0012] According to the aerobic fermenter sludge treatment method of the present invention, the auxiliary material in step S1 includes at least one of straw and sawdust.

[0013] According to the aerobic fermentation tank sludge treatment method of the present invention, the aerobic fermentation in step S2 is carried out in a vertical aerobic fermentation tank, the volume of which is 10~1000 m³.

[0014] According to the aerobic fermentation tank sludge treatment method of the present invention, the aerobic fermentation process in step S2 includes a heating stage, a high temperature stage, a cooling stage and a composting stage; the temperature of the high temperature stage is controlled at 55~65℃ and the duration is 3~7 days.

[0015] According to the aerobic fermentation tank sludge treatment method of the present invention, the aerobic fermentation tank is characterized by integrating a stirring system, a ventilation system, a temperature control system, and a deodorization system; the stirring system uses a spiral stirring paddle to achieve three-dimensional circulation and uniform mixing of materials; the ventilation system supplies oxygen evenly to the materials through a bottom air distribution device; the temperature control system monitors the temperature data of materials at different levels in real time through multi-point high-precision temperature sensors and automatically adjusts the ventilation volume to maintain the fermentation temperature; the deodorization system purifies the waste gas generated during the fermentation process through a biological filter or a chemical washing device.

[0016] According to the aerobic fermentation tank sludge treatment method of the present invention, the variable frequency fan adopts variable frequency control and dynamically adjusts the air volume according to the fermentation stage; the stirring device has an anti-sticking structure to prevent the material from forming a crust on the tank wall.

[0017] According to the aerobic fermentation tank sludge treatment method of the present invention, the aerobic fermentation process in step S2 is characterized by real-time monitoring of temperature and oxygen concentration through an intelligent monitoring system, wherein the intelligent monitoring system supports simultaneous display on touch screen and cloud multi-terminal.

[0018] According to the aerobic fermentation tank sludge treatment method of the present invention, the organic fertilizer product in step S3 has a moisture content reduced to below 30% and a volume reduction of 60% to 70%.

[0019] The aerobic fermenter sludge treatment method according to the present invention is characterized in that the method adopts a fully enclosed treatment, and the leachate and odor generated during the fermentation process are 100% treated after collection.

[0020] The aerobic fermentation tank sludge treatment method according to the present invention is characterized in that the aerobic fermentation tank is made of stainless steel and adopts an integrated design that integrates stirring, ventilation, temperature control and deodorization functions to achieve fully automated operation.

[0021] The aerobic fermentation tank sludge treatment method according to the present invention is characterized in that the method is applicable to the treatment of at least one organic waste among municipal sludge, livestock farm manure, kitchen waste and agricultural waste.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses multi-point temperature sensors to monitor the temperature data of different layers of the material in real time, and combines this with an intelligent temperature control system to automatically adjust the ventilation volume, precisely controlling the fermentation temperature within the optimal range of 55-65℃. The high-temperature period (55-65℃) lasts for 3-7 days, effectively killing pathogens, parasite eggs, and weed seeds, achieving harmless treatment of the material. Simultaneously, the variable frequency fan dynamically adjusts the ventilation volume according to the fermentation stage, avoiding the drawbacks of fixed ventilation volume and inability to supply oxygen as needed in traditional processes. The synergistic effect of multi-point real-time temperature monitoring and intelligent feedback adjustment mechanism ensures that the fermentation process is always under optimal conditions, effectively shortening the fermentation cycle (7-15 days) and improving the quality stability of the fermentation product.

[0023] 2. This invention employs a specially designed spiral stirring paddle to achieve three-dimensional circulation and uniform mixing of materials. Compared to traditional manual turning or simple mechanical stirring, three-dimensional circulation stirring enables materials to be rotten and mixed in all directions within the tank, eliminating anaerobic dead zones and effectively preventing ventilation problems caused by material compaction due to gravity. The special anti-sticking structure of the stirring device effectively prevents material from forming a crust on the tank wall, ensuring continuous and stable heat and mass transfer. The synergistic effect of three-dimensional stirring and the uniform oxygen supply from the bottom gas distribution system ensures consistent fermentation progress in all areas of the tank, avoiding localized hypoxia or overheating, and significantly improving fermentation uniformity and processing efficiency.

[0024] 3. This invention employs a vertical aerobic fermentation tank structure, integrating stirring, ventilation, temperature control, and deodorization functions. The vertical structure fully utilizes vertical space, significantly increasing the processing capacity per unit area compared to traditional windrow or trough composting. The integrated design reduces material transfer links between equipment, lowering system energy consumption. The intelligent adjustment of the variable frequency fan saves over 30% more energy compared to traditional fixed-frequency ventilation. Furthermore, the stainless steel tank body is highly corrosion-resistant and has a long service life, while the fully enclosed design ensures 100% collection and treatment of leachate and odor generated during fermentation, preventing secondary pollution.

[0025] 4. After treatment by the method of this invention, the sludge volume is reduced by 60%~70%, and the moisture content of the organic fertilizer product is reduced to below 30%, achieving a significant volume reduction effect. The fermentation product is a high-quality organic fertilizer rich in humus, which can be widely used in soil improvement, landscaping, and organic agriculture. The product has a high organic matter content, which can improve soil aggregate structure and enhance water and fertilizer retention capacity. This invention completely changes the predicament of unusable sludge nutrients under traditional landfill methods, transforming sludge from "waste" into "resource," realizing high-value resource utilization by "turning waste into treasure."

[0026] 5. This invention achieves fully automated control of the entire fermentation process through an intelligent monitoring system, supporting real-time monitoring of key fermentation parameters such as temperature and oxygen concentration across multiple terminals, including touchscreens and the cloud. Operators only need to start the entire fermentation process from feeding to discharging with a single button, eliminating the need for dedicated personnel. Engineers can remotely diagnose faults and adjust parameters, significantly reducing on-site maintenance costs. Fully automated operation avoids the problems of heat loss and high labor intensity caused by traditional manual turning operations, significantly improving the industrial applicability of the process.

[0027] 6. The method of this invention is not only applicable to the treatment of municipal sludge, but can also be extended to the treatment of various organic wastes such as livestock manure, kitchen waste, and agricultural waste. In terms of environmental benefits, this invention reduces the need for landfill space and lowers emissions of greenhouse gases such as methane and carbon dioxide. In terms of economic benefits, the treatment cost of this invention is lower than traditional landfill and incineration processes, and the produced organic fertilizer products can be directly sold to generate income. Furthermore, it complies with national environmental protection policies and can apply for relevant subsidies, thus achieving a unified balance between environmental and economic benefits.

[0028] In summary, this invention, through the synergistic innovation of intelligent temperature control, three-dimensional stirring, dynamic ventilation, and integrated tank design, effectively solves the technical problems existing in current aerobic fermentation sludge treatment technologies, such as long fermentation cycles, large footprints, extensive manual operations, low automation, and high energy consumption. It achieves sludge reduction, harmlessness, stabilization, and resource utilization, demonstrating significant technological advancement and broad prospects for widespread application. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the embodiments, and the technical solutions in the embodiments of the present invention will be clearly and completely described. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] This invention provides a method for treating sludge from an aerobic fermenter, comprising the following steps: S1: Raw material pretreatment: Dewatered sludge with a moisture content of 70%~85% is mixed with auxiliary materials in a certain proportion, the moisture content of the materials is adjusted to 50%~65% and the carbon-nitrogen ratio is adjusted to 20~30:1, and then crushed and mixed evenly to obtain pretreated materials; S2: Aerobic fermentation: The pretreated material is fed into an aerobic fermentation tank and aerobic fermentation is carried out under oxygen supply conditions. During the fermentation process, the material temperature is monitored in real time by multiple temperature sensors, and the fermentation temperature is controlled at 55~65℃ by an intelligent temperature control system. The fermentation cycle is 7~15 days, and the fermentation product is obtained. S3: Post-processing: The fermentation product is screened and cooled to remove impurities and obtain organic fertilizer product; In the aerobic fermentation process, the material is stirred in a three-dimensional circulation using a stirring device, and the ventilation volume is dynamically adjusted by a variable frequency fan according to the fermentation stage to provide oxygen for microbial metabolism.

[0031] The auxiliary materials mentioned in step S1 include at least one of straw and sawdust.

[0032] The aerobic fermentation described in step S2 is carried out in a vertical aerobic fermenter with a volume of 10~1000 m³.

[0033] The aerobic fermentation process in step S2 includes a heating stage, a high-temperature stage, a cooling stage, and a composting stage; the temperature in the high-temperature stage is controlled at 55~65℃ and lasts for 3~7 days.

[0034] The aerobic fermenter is integrated with a stirring system, a ventilation system, a temperature control system, and a deodorization system. The stirring system uses a spiral agitator to achieve three-dimensional circulation and uniform mixing of materials. The ventilation system supplies oxygen evenly to the materials through a bottom air distribution device. The temperature control system monitors the temperature data of materials at different levels in real time through multiple high-precision temperature sensors and automatically adjusts the ventilation volume to maintain the fermentation temperature. The deodorization system purifies the waste gas generated during the fermentation process through a biological filter or chemical washing device.

[0035] The variable frequency fan uses variable frequency control to dynamically adjust the air volume according to the fermentation stage; the stirring device has an anti-sticking structure to prevent the material from forming a crust on the tank wall.

[0036] During the aerobic fermentation process described in step S2, the temperature and oxygen concentration are monitored in real time by an intelligent monitoring system, which supports simultaneous display on touch screens and cloud platforms.

[0037] In step S3, the moisture content of the organic fertilizer product is reduced to below 30%, and its volume is reduced by 60% to 70%.

[0038] The method employs a fully enclosed process, and the leachate and odor generated during fermentation are collected and 100% treated.

[0039] The aerobic fermenter is made of stainless steel and features an integrated design that incorporates stirring, ventilation, temperature control, and deodorization functions, enabling fully automated operation.

[0040] The method is applicable to the treatment of at least one organic waste among municipal sludge, livestock manure, kitchen waste, and agricultural waste.

[0041] Example 1 I. Project Overview A municipal wastewater treatment plant (hereinafter referred to as "the plant") has a designed wastewater treatment capacity of 80,000 m³ / d, producing approximately 40 tons of dewatered sludge (with a moisture content of about 80%) daily. For a long time, the plant's sludge has primarily been transported to the municipal landfill for sanitary landfill disposal, with an average annual landfill cost of approximately 3.6 million yuan (based on 250 yuan / ton). With the upgraded implementation of the national standard for "Mixed Landfill Sludge," the compliance threshold for sludge landfill has significantly increased. In response to national policies, to reduce disposal costs, and to achieve sludge resource utilization, the plant initiated the construction of a sludge aerobic fermentation resource utilization project in 2024.

[0042] The project has a total investment of approximately 12 million yuan, covering an area of ​​approximately 1,500 square meters. Construction includes: one unloading and mixing workshop; four vertical aerobic fermentation tanks ranging from 10 to 1,000 m³ (each tank with an effective volume of 50 m³, total processing capacity of 40 tons / day); one aging workshop; one packaging workshop; and supporting waste gas treatment systems (four-stage spray scrubbing towers), wastewater collection and treatment facilities, and an automated control system. The project was completed and put into operation in March 2025, achieving fully automated operation throughout the entire process.

[0043] II. Process Flow This embodiment implements aerobic fermentation tank sludge treatment according to the following steps: (a) Raw material pretreatment The dewatered sludge produced in this plant is transported to the unloading and mixing workshop via screw pumps. The initial moisture content of the sludge is 78%~83%, and the carbon-to-nitrogen ratio is approximately 8~12:1, which does not directly meet the optimal conditions for aerobic fermentation. Operators mix the sludge with straw powder at a mass ratio of approximately 4:1, while adding a small amount of sawdust to increase the material's bulkiness. After being crushed by a crusher, the mixture is thoroughly stirred in a twin-screw mixer to reduce the moisture content to 55%~60% and adjust the carbon-to-nitrogen ratio to 22~28:1, obtaining the pretreated material. The uniformity of mixing directly affects the subsequent fermentation effect; in this embodiment, the mixing quality is ensured through controlled stirring time (no less than 15 minutes) and sampling tests.

[0044] (II) Aerobic fermentation The pretreated material is fed into a vertical aerobic fermenter via a belt conveyor. The fermenter used in this embodiment is a vertical cylindrical structure made of stainless steel, with an effective volume of 50 m³. It integrates a stirring system, a ventilation system, a temperature control system, and a deodorization system. The stirring system uses a spiral agitator to achieve three-dimensional circulation and uniform mixing of the material; the ventilation system supplies oxygen evenly to the material through a bottom air distribution device; the temperature control system uses multiple high-precision temperature sensors at different heights within the tank to monitor the material temperature data in real time.

[0045] After loading, start the fermentation tank operation program. The fermentation process consists of four stages: Heating phase (days 1-2): Microorganisms begin to decompose organic matter, and the material temperature gradually rises from room temperature. During this phase, ventilation is low, and stirring is performed once every 4 hours.

[0046] High-temperature stage (days 3-7): The material temperature rises to 55-65℃. The temperature control system automatically adjusts the ventilation volume based on feedback data from multiple sensors to stabilize the temperature within the optimal fermentation range. This high-temperature period lasts for 5 days, effectively killing pathogens, parasite eggs, and weed seeds, achieving harmless treatment of the material. During this stage, the stirring frequency is increased to once every 2 hours to ensure thorough agitation of the material and even oxygen distribution.

[0047] Cooling phase (days 8-10): Easily decomposable organic matter is largely depleted, microbial activity weakens, and the material temperature gradually decreases. The variable frequency fan automatically reduces the ventilation volume based on temperature feedback, and the stirring frequency is reduced to once every 6 hours.

[0048] Fermentation stage (days 11-14): The material temperature approaches the ambient temperature, the organic matter is fully degraded into stable humus, and the fermentation process ends.

[0049] The entire fermentation cycle takes 14 days. During fermentation, an intelligent monitoring system displays key parameters such as temperature and oxygen concentration in real time, supporting simultaneous viewing via touchscreen and cloud. The biofilter built into the fermenter biologically purifies the generated waste gas, ensuring no secondary pollution. The leachate produced during fermentation is collected and treated at the plant's wastewater treatment station.

[0050] (III) Post-processing After fermentation, the material is discharged from the bottom outlet of the fermentation tank and conveyed by belt conveyor to the aging workshop for secondary composting (approximately 3-5 days). It then enters the screening process, where a drum screen removes large impurities that have not been fully degraded (such as large pieces of straw residue). The screened material is cooled to room temperature, reducing its moisture content to below 30% and its volume to approximately 65%. Some of the material is directly packaged and stored as powdered organic nutrient soil, while some is processed into granular organic fertilizer products using a granulator. The finished product, after passing inspection, is stored for sale.

[0051] III. Operational Results The monitoring data from 12 consecutive months of operation in this embodiment are as follows: Treatment effect indicators

[0052] (ii) Operational stability After the project goes into operation, it will run for more than 350 days a year. The intelligent temperature control system will precisely control the fermentation temperature within the range of 55~65℃, with a fluctuation range of no more than ±2℃. The three-dimensional circulating stirring effectively eliminates anaerobic dead zones in the tank, ensuring stable product quality for each batch. The variable frequency fan saves approximately 32% more energy than the traditional fixed frequency ventilation mode.

[0053] IV. Benefit Analysis (a) Environmental benefits Reduced land occupation: This embodiment can process approximately 14,600 tons of dewatered sludge annually (based on 40 tons / day × 365 days), with approximately 5,000 tons of processed material, resulting in a volume reduction of approximately 65%, which is equivalent to reducing landfill land occupation by approximately 8 acres per year.

[0054] Reduced carbon emissions: Compared to traditional landfilling, aerobic fermentation avoids the large-scale emission of greenhouse gases such as methane; compared to incineration, it does not require auxiliary fuel, resulting in a significant reduction in carbon emissions.

[0055] Eliminating secondary pollution: The fully enclosed fermentation system, combined with a four-stage spray scrubbing tower, purifies the exhaust gas, reducing odor emission concentration by more than 50% compared to traditional open composting; leachate is 100% collected and treated, achieving zero emissions of pollutants.

[0056] Resource recycling: The organic matter and nitrogen, phosphorus and potassium nutrients in the sludge are "taken from the soil and used in the soil", thus constructing a complete ecological cycle chain.

[0057] (II) Economic Benefits The disposal cost is significantly reduced: the traditional landfill disposal cost is about 250-300 yuan / ton (including transportation and landfill costs). The direct operating cost of the aerobic fermentation treatment in this embodiment is about 57 yuan / ton of wet sludge, and the comprehensive cost (including equipment depreciation, labor, energy consumption, auxiliary materials, etc.) is about 120 yuan / ton. Compared with the landfill method, the annual disposal cost is reduced by about 1.9 million yuan (calculated based on 40 tons / day × 330 days × (250-120) yuan / ton).

[0058] Revenue from resource-based products: The annual production of organic nutrient soil is approximately 5,000 tons. Based on a market price of 300-500 yuan / ton, the annual sales revenue is approximately 1.5-2.5 million yuan. The products are mainly sold to local landscaping companies, nurseries, and organic farms.

[0059] Policy subsidy benefits: The project is in line with the national policy direction for the resource utilization of sludge and can apply for the "three-year exemption and three-year half-reduction" of income tax and local special financial subsidies. It is estimated that the annual subsidy income will be about 500,000 to 800,000 yuan.

[0060] Overall benefits: Considering the cost savings, product sales revenue, and policy subsidies, the project is expected to have a payback period of about 3 to 4 years, demonstrating good economic feasibility.

[0061] Example 2 The difference between this embodiment and Embodiment 1 lies in the type and scale of the objects being processed.

[0062] A large-scale pig farm has approximately 50,000 pigs and generates about 60 tons of livestock manure daily (with a moisture content of about 85%). The traditional method of disposal is open-air dumping, which not only occupies a large amount of land but also causes serious odor pollution and leachate problems, resulting in repeated penalties from environmental protection departments.

[0063] This embodiment uses the same aerobic fermentation tank sludge treatment method as Example 1, but the pretreatment process has been adjusted according to the characteristics of the manure: livestock manure and straw powder are mixed at a ratio of 3:1, and the moisture content is adjusted to 55%~60% and the carbon-nitrogen ratio to 25~30:1. Because livestock manure has a high nitrogen content, the proportion of auxiliary materials added is slightly higher than that used for municipal sludge treatment. The fermentation cycle is 12 days, and the remaining process parameters are the same as in Example 1.

[0064] After treatment, the product's moisture content is reduced to 28%, its volume shrinks by approximately 70%, and its organic matter content is ≥35%. The finished organic fertilizer is used as base fertilizer in surrounding orchards and vegetable bases, replacing some chemical fertilizers and saving approximately 200 yuan per mu in fertilizer costs. It also improves soil structure and enhances the quality of agricultural products. The project processes approximately 22,000 tons of manure annually, producing approximately 7,000 tons of organic fertilizer annually, generating annual sales revenue of approximately 2.8 million yuan, achieving zero emissions and full resource utilization of livestock waste.

[0065] Example 3 The difference between this embodiment and Embodiment 1 lies in the configuration scale of the fermenter.

[0066] A centralized sludge treatment center in a prefecture-level city serves three wastewater treatment plants throughout the city, receiving approximately 100 tons of dewatered sludge daily. The project is equipped with 10 vertical aerobic fermenters with an effective volume of 100 m³, employing a "batch feeding, continuous discharge" operation mode, with each batch of material having a fermentation cycle of 15 days.

[0067] In the pretreatment stage, sludge is mixed with sawdust and recycled materials (part of the fermented products) in a specific ratio, and the moisture content is adjusted to 50%~55%. The addition of recycled materials helps to quickly establish a microbial population and shorten the heating phase. During fermentation, an intelligent temperature control system maintains the temperature at 60~65℃ for 6 days during the high-temperature period to ensure thorough elimination of pathogens.

[0068] The project has an annual sludge treatment capacity of approximately 36,500 tons and an annual production capacity of approximately 13,000 tons of organic nutrient soil. The finished products are mainly supplied to surrounding mine ecological restoration and saline-alkali land improvement projects. The total investment of the project is approximately RMB 35 million, with an annual operating cost of approximately RMB 4.38 million (based on RMB 120 / ton), annual product sales revenue of approximately RMB 5.2 million to 6.5 million (based on RMB 400 to 500 / ton), and a comprehensive annual income of approximately RMB 800,000 to 2.1 million. The investment payback period is approximately 5 to 6 years.

[0069] Example 4 The difference between this embodiment and Embodiment 1 is that it involves the synergistic treatment of multiple organic wastes.

[0070] A certain urban and rural organic waste treatment center simultaneously receives municipal sludge (30 tons / day), kitchen waste (20 tons / day), and garden waste (10 tons / day). The three types of waste are mixed in proportion and then co-treated using the same aerobic fermentation tank treatment method as in Example 1.

[0071] Kitchen waste has a high oil content, so an oil separation process needs to be added during pretreatment. Garden waste (dried branches and leaves, etc.) can be crushed and used as a high-quality auxiliary material to replace part of the straw, which not only solves the problem of garden waste disposal, but also reduces the procurement cost of auxiliary materials. The mixed materials are adjusted to a moisture content of 55%~60% and a carbon-nitrogen ratio of 20~25:1 before entering the fermentation tank.

[0072] The fermentation cycle is 15 days. After screening, the product yields high-quality organic nutrient soil with an organic matter content of ≥35% and a total nutrient content of ≥4%. The project processes approximately 22,000 tons of organic waste annually and produces approximately 8,000 tons of organic fertilizer annually, achieving synergistic resource utilization of various organic wastes and demonstrating significant comprehensive regional environmental benefits.

[0073] 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. A method for treating sludge from an aerobic fermenter, characterized in that, Includes the following steps: S1: Raw material pretreatment: Dewatered sludge with a moisture content of 70%~85% is mixed with auxiliary materials in a certain proportion, the moisture content of the materials is adjusted to 50%~65% and the carbon-nitrogen ratio is adjusted to 20~30:1, and then crushed and mixed evenly to obtain pretreated materials; S2: Aerobic fermentation: The pretreated material is fed into an aerobic fermentation tank and aerobic fermentation is carried out under oxygen supply conditions. During the fermentation process, the material temperature is monitored in real time by multiple temperature sensors, and the fermentation temperature is controlled at 55~65℃ by an intelligent temperature control system. The fermentation cycle is 7~15 days, and the fermentation product is obtained. S3: Post-processing: The fermentation product is screened and cooled to remove impurities and obtain organic fertilizer product; In the aerobic fermentation process, the material is stirred in a three-dimensional circulation using a stirring device, and the ventilation volume is dynamically adjusted by a variable frequency fan according to the fermentation stage to provide oxygen for microbial metabolism.

2. The method for treating sludge from an aerobic fermenter according to claim 1, characterized in that, The auxiliary materials mentioned in step S1 include at least one of straw and sawdust.

3. The method for treating sludge from an aerobic fermenter according to claim 1, characterized in that, The aerobic fermentation described in step S2 is carried out in a vertical aerobic fermenter with a volume of 10~1000 m³.

4. The method for treating sludge from an aerobic fermenter according to claim 1, characterized in that, The aerobic fermentation process in step S2 includes a heating stage, a high-temperature stage, a cooling stage, and a composting stage; the temperature in the high-temperature stage is controlled at 55~65℃ and lasts for 3~7 days.

5. The method for treating sludge from an aerobic fermenter according to claim 1, characterized in that, The aerobic fermenter is integrated with a stirring system, a ventilation system, a temperature control system, and a deodorization system. The stirring system uses a spiral agitator to achieve three-dimensional circulation and uniform mixing of materials. The ventilation system supplies oxygen evenly to the materials through a bottom air distribution device. The temperature control system monitors the temperature data of materials at different levels in real time through multiple high-precision temperature sensors and automatically adjusts the ventilation volume to maintain the fermentation temperature. The deodorization system purifies the waste gas generated during the fermentation process through a biological filter or chemical washing device.

6. The method for treating sludge from an aerobic fermenter according to claim 5, characterized in that, The variable frequency fan uses variable frequency control to dynamically adjust the air volume according to the fermentation stage; the stirring device has an anti-sticking structure to prevent the material from forming a crust on the tank wall.

7. The method for treating sludge from an aerobic fermenter according to claim 1, characterized in that, During the aerobic fermentation process described in step S2, the temperature and oxygen concentration are monitored in real time by an intelligent monitoring system, which supports simultaneous display on touch screens and cloud platforms.

8. The method for treating sludge from an aerobic fermenter according to claim 1, characterized in that, In step S3, the moisture content of the organic fertilizer product is reduced to below 30%, and its volume is reduced by 60% to 70%.

9. The method for treating sludge from an aerobic fermenter according to claim 1, characterized in that, The method employs a fully enclosed process, and the leachate and odor generated during fermentation are collected and 100% treated.

10. The method for treating sludge from an aerobic fermenter according to claim 1, characterized in that, The aerobic fermenter is made of stainless steel and features an integrated design that incorporates stirring, ventilation, temperature control, and deodorization functions, enabling fully automated operation.

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