Method for controlling composting for producing fertilizer from degraded organic waste

Abstract

The present application belongs to the technical field of waste treatment, and relates to a compost control method for producing and preparing fertilizer based on degradation of organic garbage, which comprises the following steps: mixing the organic garbage with wood chips and carrying out fermentation; the fermentation reaction comprises two same stages, fresh air is first introduced into a closed tunnel workshop, and the oxygen content of the tunnel workshop is controlled to be not less than 5%; then the temperature is increased, the temperature in the tunnel workshop is controlled to be increased to 70-80 DEG C, and pasteurization is carried out for three days; after the pasteurization is completed, the temperature is started to be decreased at a rate of 2-4 DEG C / h, until the temperature is decreased to 45-54 DEG C, and then the temperature is kept for a period of time, and finally the temperature is decreased to the ambient temperature; the fermented fertilizer is exposed to the sun until it is dried; and finally, the fertilizer product is obtained through fine treatment and screening. The compost control method of the present application produces fertilizer by using organic garbage, realizes waste-to-resource, and is helpful for large-scale planting of green vegetation in desert areas (such as Saudi Arabia), and effectively reduces greenhouse gas emissions.

Description

Technical Field

[0001] This invention belongs to the field of waste treatment technology, and relates to the conversion of organic waste into organic fertilizer rich in organic matter and nutrients through advanced composting control technology. Specifically, it relates to a composting control method for producing fertilizer based on the degradation of organic waste. Background Technology

[0002] In recent years, with rapid economic development and the continuous improvement of people's living standards, the production of organic waste worldwide has been increasing daily. Organic waste needs to be disposed of promptly and properly. Improper handling of organic waste will lead to a series of environmental and social problems, such as land encroachment, water and soil pollution, air pollution, and the spread of diseases. However, currently, waste in most countries is not effectively utilized or has a low utilization rate.

[0003] Organic waste treatment refers to the physical, chemical, or biological treatment of organic waste and its pollutants. Basic methods include composting, incineration, and sanitary landfill. Composting is an effective way to treat organic solid waste. It involves piling up easily decomposable waste such as food waste and garden waste, allowing the organic matter to biodegrade and form well-rotted organic fertilizer. Composting transforms the biodegradable organic matter in organic waste into nutrient-rich organic soil, effectively solving the problem of solid organic waste treatment and providing suitable humus for agricultural production. Most desert regions worldwide are unsuitable for vegetation growth, resulting in low crop yields and food shortages in large parts of the world, leaving many still struggling with hunger. Therefore, composting is particularly suitable for treating organic waste in desert areas.

[0004] Current composting systems suffer from poor odor control and low conversion rates, easily causing environmental pollution. Therefore, this invention proposes a composting control technology based on the degradation of organic waste to produce high-efficiency fertilizer, which can transform these organic wastes into organic fertilizer rich in organic matter and nutrients. Summary of the Invention

[0005] The purpose of this invention is to solve the aforementioned problems in the prior art and to propose a composting control method for producing fertilizer based on the degradation of organic waste. Organic fertilizer produced using the composting control technology of this invention can effectively improve the water retention capacity of plants, significantly reduce fertilizer usage compared to other chemical fertilizers, and effectively prevent soil and plant diseases, thereby increasing crop yields. This organic fertilizer is suitable for various geological conditions, especially for desert regions in the Middle East.

[0006] The technical solution of this invention is: This invention provides a composting control method for producing fertilizer based on the degradation of organic waste. The composting control method uses a composting system to control the reaction conditions and degrade and ferment the organic waste.

[0007] This control method can decompose organic waste at the fastest speed, possibly through anaerobic hydrolysis and acid production (both anaerobic processes), and consume the reaction products volatile fatty acids (VFA) as efficiently as possible in the aerobic zone (particle surface).

[0008] By controlling the input and process parameters of organic waste in composting tunnels, the goal of producing high-efficiency organic chemical fertilizers can be achieved. Composting is a complex chemical-biological reaction, and the control of reaction conditions, i.e., the amount of reactants, is crucial to the chemical reaction process. High-efficiency organic fertilizers produced using this control method have shown good application results in desert regions.

[0009] Biochemical equation for composting: C a H b O c N d + O2 → a CO2 + b / 2 H2O + d NH3 : heat + biomass The control method includes the following steps: (1) Organic waste collection and mixing process: Organic waste and wood chips are mixed and stirred evenly, and transported to a tunnel workshop for composting, where fermentation reaction is carried out under closed conditions; wherein the mass ratio of wood chips to organic waste is not less than 30%; (2) Organic waste fermentation reaction process: The composting fermentation reaction includes two stages. In the first stage, fresh air is first introduced into the closed tunnel workshop to control the oxygen content of the tunnel workshop to be no less than 5%. Then the temperature is raised to control the temperature in the tunnel workshop to rise to 70~80℃ and maintain it for three days for pasteurization. After sterilization, the temperature is lowered at a rate of 2~4℃ / h until the temperature drops to 45~54℃, which is maintained for a period of time, and finally the temperature is lowered to the ambient temperature. After the first stage of fermentation is completed, the compost material is transferred to another tunnel workshop to begin the second stage of fermentation. The second stage of fermentation is the same as the first stage. (3) Maturation process: Spread the fermented fertilizer evenly and expose it to the sun until it is completely dry; (4) Fine processing and screening process: The sawdust and other large-sized impurities in the fertilizer are screened out, and the resulting fine fertilizer is then separated according to its density to obtain the fertilizer product.

[0010] Furthermore, the composting system includes a composting tunnel, an air handling system, a measurement system, and a control system; The composting tunnel consists of five tunnel workshops and one pretreatment workshop. Each tunnel workshop is equipped with 12 to 20 oxygen delivery channels spaced 0.6 m apart. Each tunnel workshop is equipped with an air supply fan for providing oxygen and a recirculation fan for air circulation. The air handling system is used to purify the air in the tunnel workshop and includes a biomass filter fan, an exhaust gas treatment unit, a condenser, and a biomass filter. The measurement system includes a temperature sensor and a pressure sensor; the control system adopts a SCADA system.

[0011] Furthermore, in step (1), the mass ratio of wood chips to organic waste is 30% to 50%.

[0012] Furthermore, in step (1), organic waste is mixed with wood chips to compensate for the low pH value of the organic waste and ensure that the pH value after mixing is 6-8; at the same time, the porosity is increased.

[0013] Furthermore, in step (2), the temperature setting of the composting fermentation reaction includes: a heating stage, in which the temperature is raised to 70°C within one day and maintained at 70°C for three days for pasteurization; after the sterilization stage, the temperature is lowered to 54°C within one day and maintained at 54°C for 10 days to decompose organic matter into compost products; and finally, a cooling stage, in which the temperature is lowered from 54°C to 30°C or ambient temperature within one day.

[0014] Furthermore, in step (3), after the fermentation reaction is completed, the fertilizer obtained from the fermentation is transported out of the tunnel workshop, spread evenly in the sun for sun exposure, and turned over according to the dryness of the fertilizer until it is completely dry.

[0015] Furthermore, in step (4), the fertilizer is screened using a fine treatment device, which includes a drum screen, a hard particle separator, and a hard particle collection box. The hard particle separator includes a blower and its pipeline. After the fertilizer passes through the drum screen, large pieces of wood chips and other large-sized impurities are screened out and removed. Fine fertilizer that meets the size standard is transported to the hard particle separator. The fertilizer is blown out from bottom to top by a blower. The low-density fertilizer is transported and stored through pipelines, while the high-density impurities settle at the bottom and are conveyed to the hard particle collection box by a conveyor belt.

[0016] The beneficial effects of this invention are: (1) The composting control method for producing fertilizer based on the degradation of organic waste provided by this invention can effectively treat compost odor and process a large amount of organic waste in a short time, reducing landfill and transportation costs. When using this composting control method to treat organic waste, the organic matter will decrease less and the nitrogen loss will be less, requiring only a one-time investment.

[0017] (2) The composting control method of the present invention utilizes organic waste to produce high-efficiency fertilizer, realizing the transformation of waste into treasure, which helps desert areas (such as Saudi Arabia) to plant green vegetation on a large scale and greatly increase crop yields; at the same time, through composting, inorganic carbon is effectively converted into organic compounds, effectively reducing greenhouse gas emissions. Attached Figure Description

[0018] Figure 1 Temperature curves provided for this invention. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention provides a composting control method for the efficient production of fertilizer from microbial degradation of organic waste, applicable to desert regions such as Saudi Arabia. This composting control method decomposes organic waste by controlling conditions such as oxygen input, temperature, moisture, and pH value through a composting system. Oxygen remains on the surface of the organic waste throughout the process and cannot penetrate into the waste particles. Over 98% of the composting process is carried out under anaerobic conditions.

[0021] In one specific embodiment, taking a large-scale solid waste treatment plant in Saudi Arabia that utilizes organic waste to produce high-efficiency fertilizer as an example, its composting system includes a composting tunnel, an air handling system, a measurement system, and a control system. All instruments, equipment, and devices used in the composting system can be purchased commercially.

[0022] in: The measurement system includes temperature and pressure sensors, which can adjust and control the temperature and pressure inside the composting tunnel and monitor the composting status in real time.

[0023] The control system adopts a SCADA system, which controls the input parameters and process parameters of organic waste in the composting tunnel to achieve the goal of efficient production of organic fertilizer.

[0024] The composting tunnel is a concrete structure with excellent sealing. It consists of five tunnel workshops and one pre-treatment workshop. The pre-treatment workshop serves as a temporary storage and mixing area for organic waste, while the five tunnel workshops are the main areas where the composting fermentation process takes place.

[0025] Each tunnel workshop measures 6 meters by 16 meters. Within each tunnel workshop, 18 oxygen delivery channels are set along the length, one channel every 0.6 meters.

[0026] Five tunnel workshops share a single air supply fan to provide fresh air with sufficient oxygen content. Each tunnel workshop is equipped with a variable frequency air recirculation fan, which draws in air from the top of the tunnel and discharges it through evenly spaced holes at the bottom of the tunnel via a bypass, ensuring sufficient air circulation and fermentation reactions within the tunnel. Temperature and pressure sensors are installed at the inlet and outlet of the fan. Each tunnel workshop has a temperature sensor on both the front and back sides for real-time temperature monitoring. Before starting operation, the tunnel doors must be closed and sealed. Sealing rings are installed around the doors to effectively isolate airflow between the inside and outside of the tunnel when closed.

[0027] The air handling system, used to purify exhaust gas from the composting tunnel, consists of a variable frequency bio-filter fan, a scrubber, a condenser, and a bio-filter workshop. The bio-filter workshop has two levels: the lower level is a plastic mesh approximately 1 meter high with small pores; the upper level is composed of larger wood chips, sized to prevent them from falling through the plastic mesh.

[0028] The biomass filter fan provides negative pressure to the composting tunnel workshop. The negative pressure and air extraction volume are adjusted by baffle gates. The extracted air passes through an exhaust pipe, then through a condenser, and finally enters the waste gas treatment unit. After being discharged by the fan into the biomass filter workshop, it is released into the atmosphere. The condenser is located at the top of the system, where it condenses and dehydrates the high-humidity waste gas, and the waste liquid is discharged into a ditch through a pipe. The waste gas treatment unit purifies harmful substances in the exhaust gas through two stages of treatment. First, soluble impurities are initially cleaned by water washing, and then further purified by a sulfuric acid solution with a pH of 3-3.5. The biomass filter is composed of suspended stacked wood. Domestic water is sprayed for 2 hours a day to keep the wood moist. When the waste gas passes through the wooden biomass filter, the odor is absorbed.

[0029] In one specific embodiment, taking a large-scale solid waste treatment plant in Saudi Arabia that utilizes organic waste to produce high-efficiency fertilizer as an example, the composting control method employed includes the following steps: (1) Organic waste collection and mixing process Organic waste is mainly kitchen waste, which comes from staff canteens, hotels and other catering establishments.

[0030] Specialized garbage trucks transport kitchen waste to the pre-treatment workshop of the composting tunnel, where it is mixed with sawdust (a small amount of reeds may also be added). The resulting organic waste is then transferred by loading equipment to the unused tunnel workshop.

[0031] The composting system has a rated capacity of 5299 t / y, or an average daily capacity of 14.6 tons. Wood chips are used to absorb excess moisture from the organic waste, provide airflow gaps for the composting materials, and provide some of the energy required for the reaction. According to the manufacturer's standards, the proportion of wood chips should be greater than 30% of the organic waste.

[0032] The performance test verified the processing capacity of the tunnel workshop by starting the fermentation process of one composting tunnel with a collection volume every 6 days. That is, the amount of organic waste in each tunnel is >87.6 tons and the amount of wood chips is >26.3 tons (adjusted according to the organic waste content).

[0033] (2) Fermentation reaction process of organic waste After the mixed organic waste is transferred to the tunnel workshop for composting, the tunnel door is closed and the fermentation process is started.

[0034] The composting fermentation process is divided into two stages: the first stage lasts 16 days and the second stage lasts 15 days, for a total of 31 days to complete the composting fermentation process.

[0035] like Figure 1 As shown, the first stage includes: (11) Aeration stage: The opening of the fresh air intake damper and exhaust damper is greater than 80%. After the aeration time is manually set, it will automatically enter the next stage after the SCADA control ends. This stage is used to increase the oxygen content in the tunnel workshop, providing sufficient oxygen for the fermentation reaction.

[0036] (12) Heating stage: The stage of rapid bacterial growth in the tunnel workshop; the bacterial metabolism converts the chemical energy in the organic waste into internal energy, thereby gradually increasing the temperature inside the tunnel. The temperature rises from 20℃ to 70℃ within one day (see...). Figure 1 (Leveling and warm-up phase curve) During the heating process, the oxygen content must be greater than 5%, and the fresh air intake damper participates in the control of oxygen content under automatic adjustment.

[0037] (13) Pasteurization stage: The temperature is raised to 70°C and maintained for three days (see Figure 1 (Pasteurization phase curve), starting high-temperature sterilization.

[0038] During this stage, the fresh air intake damper is fully closed, the bypass damper is fully open, and the exhaust damper is slightly open to maintain negative pressure inside the tunnel.

[0039] (14) Cooling stage: After the pasteurization stage ends, the fresh air damper is opened, the bypass damper is closed, the exhaust damper opening is increased, and the temperature inside the tunnel begins to decrease at a rate of 2~4℃ until the temperature drops to 54℃ (see Figure 1 (The cooldown for composting stage in the middle).

[0040] (15) Conditioning phase: The temperature is maintained at 54℃ for 10 days (see Figure 1 The composting phase curve shows that organic matter decomposes into stable compost products. This phase requires the evaporation of most of the moisture. Maintaining a large opening of the fresh air intake and exhaust dampers at a temperature of 54°C helps reduce system humidity.

[0041] (16) Cooling stage: The fresh air intake and exhaust dampers are opened to the maximum extent to cool the tunnel at a rate of 2-4 °C / h until the temperature approaches the ambient temperature. Specifically, for example... Figure 1 The cooling down foremptying phase curve shown indicates that the temperature dropped from 54°C to 30°C within one day.

[0042] The first stage of the composting process has now concluded.

[0043] Because the reaction rate within the composting tunnel workshop is highly correlated with the uniformity of mixing during the pretreatment stage, the materials are re-mixed during the transfer to another tunnel workshop after the first stage. This helps to mitigate the effects of uneven mixing during the initial stage. The loader transfer takes approximately 3-4 hours. Since the first stage causes the materials to lose most of their moisture, the spray pump must be manually activated to humidify the materials during the transfer process.

[0044] The second stage of the composting process is basically the same as the first stage.

[0045] (3) Maturation process After the composting fermentation process is complete, the tunnel hatch is opened, and the fertilizer is transported to the maturation area by a loader, where it is spread evenly to be exposed to sunlight. The material is turned over according to its surface dryness until it is completely dry.

[0046] (4) Fine processing and screening process Since the source of composting materials has not undergone strict screening, some impurities may be mixed in with organic waste and wood chips, and the compost products may contain unqualified impurities due to the influence of the natural environment during the maturation process. Therefore, fine processing and screening are required.

[0047] Before feeding the refined processing equipment, it should be started in the following order from the terminal to the upstream: fertilizer product storage room conveyor belt → hard particle collection box conveyor belt → hard particle separator → hard particle separator conveyor belt → drum screen → drum screen conveyor belt → transport platform.

[0048] After all parts of the equipment are started, the loader delivers the compost material to the fine processing and transport platform. After passing through a drum screen, large pieces of sawdust (wood blocks or chips) and other large-sized impurities are screened out and transported to the screened-out stockpile area. Fine compost products that meet size standards are transported to the hard pellet separator. The hard pellet separator consists of a blower and its piping. The outlet is equipped with a manually adjustable damper to control the airflow. Because the compost product itself has a low density and is fibrous, the blower blows the product upwards, transporting it through pipes and a conveyor belt to the fertilizer storage room. Hard, high-density impurities settle at the bottom due to low air resistance, are screened out by a vibrating screen, and are transported by a conveyor belt to the hard pellet collection box.

[0049] The system shutdown sequence is the reverse of the startup sequence. The key points for commissioning the fine treatment equipment are the normal operation of each rolling device, the automatic control sequence of the start-up and shutdown devices, and the opening degree of the hard particle separator fan damper.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, alterations, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composting control method based on the production and preparation of fertilizer from degraded organic waste, characterized in that, The composting control method uses a composting system to control reaction conditions to degrade and ferment organic waste, including the following steps: (1) Organic waste collection and mixing process: Organic waste and wood chips are mixed and stirred evenly, and transported to a tunnel workshop for composting, where fermentation reaction is carried out under closed conditions; wherein the mass ratio of wood chips to organic waste is not less than 30%; (2) Organic waste fermentation reaction process: The composting fermentation reaction includes two stages. In the first stage, fresh air is first introduced into the closed tunnel workshop to control the oxygen content of the tunnel workshop to be no less than 5%. Then the temperature is raised to control the temperature in the tunnel workshop to rise to 70~80℃ and maintain it for three days for pasteurization. After sterilization, the temperature is lowered at a rate of 2~4℃ / h until the temperature drops to 45~54℃, which is maintained for a period of time, and finally the temperature is lowered to the ambient temperature. After the first stage of fermentation is completed, the compost material is transferred to another tunnel workshop to begin the second stage of fermentation. The second stage of fermentation is the same as the first stage. (3) Maturation process: Spread the fermented fertilizer evenly and expose it to the sun until it is completely dry; (4) Fine processing and screening process: The sawdust and other large-sized impurities in the fertilizer are screened out, and the resulting fine fertilizer is then separated according to its density to obtain the fertilizer product.

2. The method according to claim 1, characterized in that, The composting system includes a composting tunnel, an air handling system, a measurement system, and a control system; The composting tunnel consists of five tunnel workshops and one pretreatment workshop. Each tunnel workshop is equipped with 12 to 20 oxygen delivery channels spaced 0.6 m apart. Each tunnel workshop is equipped with an air supply fan for providing oxygen and a recirculation fan for air circulation. The air handling system is used to purify the air in the tunnel workshop and includes a biomass filter fan, an exhaust gas treatment unit, a condenser, and a biomass filter. The measurement system includes a temperature sensor and a pressure sensor; the control system adopts a SCADA system.

3. The method according to claim 1, characterized in that, In step (1), the mass ratio of wood chips to organic waste is 30% to 50%.

4. The method according to claim 1, characterized in that, In step (1), organic waste is mixed with wood chips to compensate for the low pH value of the organic waste and ensure that the pH value after mixing is 6-8; at the same time, the porosity is increased.

5. The method according to claim 1, characterized in that, In step (2), the temperature setting of the composting fermentation reaction includes: a heating stage, in which the temperature is raised to 70°C within one day and maintained at 70°C for three days for pasteurization; after the sterilization stage, the temperature is lowered to 54°C within one day and maintained at 54°C for 10 days to decompose organic matter into compost products; and finally, a cooling stage, in which the temperature is lowered from 54°C to 30°C or ambient temperature within one day.

6. The method according to claim 1, characterized in that, In step (3), after the fermentation reaction is completed, the fertilizer obtained from the fermentation is transported out of the tunnel workshop, spread evenly in the sun for sun exposure, and turned over according to the dryness of the fertilizer until it is completely dry.

7. The method according to claim 1, characterized in that, In step (4), the fertilizer is screened using a fine treatment device. The fine treatment device includes a drum screen, a hard particle separator, and a hard particle collection box. The hard particle separator includes a blower and its pipeline. After the fertilizer passes through the drum screen, large pieces of wood chips and other large-sized impurities are screened out and removed. Fine fertilizer that meets the size standard is transported to the hard particle separator. The fertilizer is blown out from bottom to top by a blower. The low-density fertilizer is transported and stored through pipelines, while the high-density impurities settle at the bottom and are conveyed to the hard particle collection box by a conveyor belt.

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