A method for preparing a fertilizer using organic waste
By using an iron-manganese bimetallic additive and a pulse oscillation control mode during the fermentation process of organic waste, free ammonia is catalyzed to be converted into stable macromolecular nitrogen, solving the problems of nitrogen loss and sensor damage, and achieving efficient nitrogen conversion and system stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BAODING REEVES ENVIRONMENTAL TECH CO LTD
- Filing Date
- 2026-03-18
- Publication Date
- 2026-06-09
Smart Images
Figure CN122167202A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of solid waste treatment and resource utilization technology, specifically a method for preparing fertilizer using organic waste. Background Technology
[0002] Organic wastes such as livestock and poultry manure and crop straw are typically processed into fertilizers through aerobic fermentation. This method converts the nutrients in the waste into forms that plants can absorb, thus achieving the recycling of agricultural resources. Retaining nitrogen during fermentation is crucial for producing high-quality fertilizers.
[0003] Currently, when dealing with ammonia production during fermentation, the industry often adds inorganic acids or porous materials like zeolites directly into the fermentation pile. Adding acid can instantly neutralize the volatilized ammonia. The porous materials, utilizing their large specific surface area, quickly adsorb free ammonia molecules into their pores, resulting in a very rapid initial effect. Regarding fermentation airflow control, factories generally use continuous forced ventilation or intermittent air supply at fixed intervals. Continuous airflow ensures sufficient oxygen in the material layer, allowing aerobic microorganisms to multiply rapidly and quickly raise the pile temperature. Timed intermittent airflow greatly simplifies the design of the workshop's electrical control system. To obtain operational data from the fermentation pile, the probes of physicochemical sensors are typically inserted directly into the fermentation substrate. This in-situ direct insertion method eliminates the need for cumbersome external gas sampling pipelines and provides real-time internal readings without delay.
[0004] However, these conventional practices have significant limitations in complex solid-state fermentation systems. The internal temperature of the fermentation pile often reaches high levels of 60℃-70℃, requiring constant turning. Physical adsorption is extremely fragile under such high temperatures and mechanical disturbances. Ammonia temporarily trapped in the pores easily dissipates again, resulting in a significant loss of total nitrogen later on. Conventional ventilation logic exacerbates this loss. Continuous air pressure generates a strong physical stripping effect, forcibly blowing away the ammonia just generated between materials. Blindly starting and stopping on a timed schedule completely deviates from the actual biochemical oxygen demand rhythm inside. The control system has no idea whether the reaction is currently oxygen-deficient, and cannot find a balance between retaining ammonia and maintaining an aerobic state. Directly inserting measurements into the solid-phase pile is also unsustainable in long-term engineering applications. Real composting sites are characterized by high temperatures and humidity, mixed with large amounts of dust and corrosive gases. Precision probes are directly exposed to the murky multiphase mud, and their surfaces are easily covered by condensate and particulate matter. Moisture and blockage of the probe can lead to serious inaccuracies and drifts in measurement data, and may even cause expensive equipment to corrode and become unusable prematurely, making precise feedback control of the entire microenvironment impossible. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing fertilizer using organic waste. This method addresses the problems of nitrogen loss due to the volatilization of free ammonia during the fermentation process of organic waste, low reaction efficiency of conventional nitrogen retention methods in solid-state fermentation systems, and the easy damage and inaccuracy of conventional sensor probes when directly inserted into the harsh environment of the waste pile.
[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing fertilizer using organic waste includes the following steps: (1) The organic waste substrate is fed into the fermentation tank for stacking, the bottom fan is turned on for continuous forced ventilation, and the temperature of the core area of the stack is monitored; (2) When the temperature in the core area of the pile rises to the preset high temperature threshold, spray the composite additive aqueous solution evenly into the organic waste matrix and mix it evenly; the composite additive aqueous solution contains sodium lignosulfonate, ferrous sulfate heptahydrate and manganese sulfate monohydrate. (3) After the composite additive aqueous solution is sprayed, the continuous forced ventilation mode is cut off and switched to the pulse oscillation control mode controlled by the gas phase oxygen concentration analyzer; the oxygen concentration is measured by extracting the interstitial gas in the stack and sending it into the oxygen concentration analyzer, and the start and stop of the bottom fan is controlled according to the preset upper and lower limit thresholds of the interstitial gas oxygen concentration. (4) After the control period of the pulse oscillation control mode ends, the interlock control is released, intermittent ventilation is restored, and fertilizer products are obtained when the temperature and moisture content of the core area of the pile drop to the preset discharge standard.
[0007] By employing the above technical solution, this invention combines a specific lignin adjuvant containing iron and manganese bimetallic compounds with pulse oscillation control based on interstitial oxygen concentration feedback. The high-temperature heat energy generated by the fermentation pile itself drives the chemical reaction, thereby converting highly volatile free ammonia into stable, macromolecularly bound organic nitrogen. The specific reaction principle mainly consists of catalytic fixation at the chemical level and gas-solid mass transfer regulation at the engineering level.
[0008] In terms of chemical transformation, when the reactor temperature rises to the high-temperature stage, with the intervention of composite additives, ferrous sulfate heptahydrate and manganese sulfate monohydrate dissociate into iron and manganese ions in the liquid film. At this time, during the pulsed oxygen supply stage, oxygen acts as an electron acceptor, and the iron-manganese bimetallic ions undergo cyclical transformations of redox potential in this microenvironment. This synergistic effect of the bimetallic compounds can effectively catalyze the single-electron transfer of the phenolic hydroxyl groups in sodium lignin sulfonate, removing hydrogen protons and subsequently oxidizing them into highly chemically active quinones, mainly ortho- or para-quinone structures.
[0009] The specific process of the catalytic oxidation reaction is as follows: Under the synergistic catalytic action of iron ions and manganese ions, the phenolic hydroxyl groups on the lignin macromolecular skeleton undergo an oxidation-reduction reaction with oxygen in the system. The phenolic hydroxyl groups are dehydrogenated and oxidized to quinone structures, while water is generated.
[0010] Along with the formation of the aforementioned highly reactive quinones, these strongly electrophilic intermediates immediately undergo a Michael nucleophilic addition reaction with the ammonia gas released from the degradation of organic matter. Specifically, the lone pair of electrons on the ammonia molecule directly attacks and binds to the carbon atoms on the quinone ring, forming a stable carbon-nitrogen covalent bond. Through this reaction step, the ammonia, which was originally in a gaseous state and easily dissipated, is firmly fixed within the macromolecular framework of lignin.
[0011] The specific process of the nucleophilic addition reaction is as follows: the highly active lignin intermediate with quinone structure undergoes Michael addition with free ammonia molecules, and the nitrogen atom in the ammonia molecule is covalently bonded to the lignin backbone, ultimately generating a structurally stable aminated lignin macromolecule polymer.
[0012] However, simply adding agents to solid compost has very limited actual reaction efficiency. This leads to the physical control mechanism at the engineering level in this solution. This invention relies on interlocked control of interstitial gas oxygen concentration to construct a pulsed oscillating microenvironment. Specifically, when the blower stops and the compost pile is in an oxygen-deficient, static state, a large amount of ammonia gas will be released and accumulated in the material voids. This greatly prolongs the contact time between ammonia gas and the composite additive liquid film, providing a sufficient window for the aforementioned chemical addition reaction to occur. When the oxygen concentration drops to the set lower limit, the system automatically triggers a short-term air supply. This instantaneous oxygen replenishment operation can maintain the aforementioned metal catalytic cycle without interruption. More importantly, this solution uses a method of extracting interstitial gas from inside the compost pile to the outside for oxygen partial pressure measurement, completely detaching the sensor probe from the fermentation substrate layer filled with corrosive substances and a large number of solid particles, fundamentally solving the problem of probe damage. By combining these aspects synergistically, the total nitrogen retention rate is ultimately improved and the process system is operated stably.
[0013] Preferably, in step (1), the organic waste substrate is prepared by mixing fresh chicken manure and corn stalks crushed to a particle size of less than 5 mm at a dry basis mass ratio of 2-4:1. The initial carbon-nitrogen ratio of the organic waste substrate is 20:1-30:1, and the initial mass moisture content is 55.0%-65.0%.
[0014] By employing the above technical solution and limiting the initial carbon-nitrogen ratio and moisture content within this range, the main purpose is to create a suitable nutrient and moisture foundation for the aerobic microbial community inside the fermentation pile. With these basic conditions, the fermentation pile can rapidly heat up, thereby reaching the thermodynamic temperature threshold necessary for subsequent bimetallic catalytic reactions in a relatively short time.
[0015] Preferably, the aqueous solution of the composite additive is prepared from the following raw materials in parts by weight: 2.0-5.0 parts sodium lignosulfonate, 1.5-3.0 parts ferrous sulfate heptahydrate, 0.2-1.0 parts manganese sulfate monohydrate, and 20.97-27.0 parts water.
[0016] By adopting the above technical solution, the iron element introduced into the formulation is mainly responsible for providing the basic catalytic oxidation power, while the manganese element acts as a buffer to regulate the redox potential of the entire system. The combination of the two can prevent the lignin substrate from being over-oxidized or even decomposed. In addition, preparing the adjuvant into an aqueous solution can reduce the viscosity during mixing, allowing metal ions and lignin macromolecules to be more evenly dispersed in the complex fermentation compost. This macroscopically increases the effective collision probability at the solid-liquid-gas multiphase interface.
[0017] Preferably, the sodium lignosulfonate has a weight-average molecular weight of 5000 Da to 50000 Da, a sulfonic acid group content of 0.5 mmol / g to 2.5 mmol / g, and a phenolic hydroxyl group mass fraction of greater than or equal to 1.5%.
[0018] By employing the above technical solution and limiting the mass fraction of phenolic hydroxyl groups, it is possible to ensure that the lignin adjuvant itself has a sufficient number of reactive sites to generate the required quinone groups. Keeping the molecular weight between 5000 Da and 50000 Da is beneficial in two ways: firstly, the polymer needs good water solubility to ensure liquid film flowability; secondly, appropriate steric hindrance and its sulfonic acid groups help the final fermentation product better retain moisture.
[0019] Preferably, the preparation steps of the composite auxiliary aqueous solution are as follows: sodium lignosulfonate, ferrous sulfate heptahydrate and manganese sulfate monohydrate are put into a mixing tank equipped with mechanical stirring, water at a temperature of 15℃-30℃ is added, and the mixture is stirred continuously at a speed of 200r / min for 30 minutes to prepare a homogeneous aqueous solution with a total solute mass concentration of 15.0%-25.0%.
[0020] The above technical solution is adopted to prepare an aqueous solution under these process parameters, mainly because sodium lignosulfonate is prone to self-aggregation and clumping if the concentration is too high or the temperature is unsuitable. By controlling the water temperature between 15℃ and 30℃ and the concentration boundary between 15.0% and 25.0%, a homogeneous solution that is not prone to stratification can be stably prepared.
[0021] Preferably, in step (1), thermocouples are used to monitor the temperature of the reactor core area, and the ventilation volume for continuous forced ventilation is set to 0.05 m³ / s. 3 / (min·m 3 -0.15m 3 / (min·m 3 ).
[0022] By adopting the above technical solution, a relatively mild and continuous forced ventilation volume can be provided in the early stage of pile fermentation, which can provide the necessary basic oxygen support for the early reproduction and metabolism of aerobic microorganisms, thereby helping the entire pile to shorten the early heating period.
[0023] Preferably, in step (2), the preset high temperature threshold is 55℃-65℃; the absolute mass of the sprayed composite additive aqueous solution in every 100kg of dry organic waste matrix is 24.67kg-36.0kg.
[0024] The choice of spraying the additive within the temperature window of 55℃ to 65℃, achieved through the aforementioned technical solution, is because this stage coincides with the peak period of ammonia volatilization in the entire fermentation system. Injecting the additive at this time allows the high-temperature environment generated by fermentation to lower the activation energy of subsequent nucleophilic addition reactions. Furthermore, strictly defining the relationship between the amount of additive sprayed and the dry substrate avoids situations where insufficient addition fails to achieve nitrogen fixation, or excessive addition leads to a surge in localized moisture content in the material, thereby causing abnormal cooling of the pile and localized anaerobic problems.
[0025] Preferably, the specific parameters in step (3) are set as follows: the lower limit threshold for interstitial oxygen concentration is set to 1.0 vol%-2.0 vol%, and the upper limit threshold is set to 10.0 vol%-15.0 vol%; when the interstitial oxygen concentration is greater than the upper limit threshold, the bottom fan stops; when the interstitial oxygen concentration drops to the lower limit threshold, forced ventilation is triggered, and the ventilation volume is 0.30 m³ / h. 3 / (min·m 3 -0.50m 3 / (min·m 3 The duration of a single pulse air supply is 3 to 10 minutes; when the oxygen concentration in the interstitial air rises back to the upper limit threshold, the system is forced to shut down again; the control period of the pulse oscillation control mode is 48 to 72 hours.
[0026] By adopting the above technical solution, this set of parameters essentially artificially creates a regular oscillation of the oxygen partial pressure in the reactor microenvironment between 1.0 vol% and 15.0 vol%. When the blower stops and the reactor is stationary, the blow-off effect caused by ventilation is weakened, and the volatilized ammonia is temporarily trapped inside the material. When the oxygen is consumed to the near-oxygen-deficient range of 1.0 vol% to 2.0 vol%, a short but high-intensity pulse airflow is triggered. This high-pressure airflow can instantly break through the gas film resistance between the material layers, rapidly replenishing oxygen electron acceptors to the iron-manganese catalytic centers waiting to react. The total duration of 48 to 72 hours basically covers the core high-temperature and intense ammonia production period, maximizing the conversion rate of free ammonia.
[0027] Preferably, in step (3), a stainless steel sintered mesh filter head inserted into the reactor body is used to continuously extract interstitial gas from the reactor body and send it to a gas phase oxygen concentration analyzer.
[0028] By adopting the above technical solution, the stainless steel sintered mesh filter head is directly inserted into the reactor core. Utilizing its inherent microporous interception characteristics, preliminary physical-level gas-solid separation can be completed as the gas is extracted. This effectively prevents dust particles and excess condensate from flowing back into the analyzer through the gas pipe, thus preserving the authenticity and accuracy of oxygen concentration monitoring data at the hardware connection level.
[0029] Preferably, in step (4), intermittent ventilation is performed alternately for 10 minutes and standing for 50 minutes; the preset discharge standard is: the temperature of the core area of the pile drops to 5℃-10℃ higher than the ambient temperature, and the mass moisture content drops to 25.0%-29.5%.
[0030] By adopting the above technical solution, after the core pulse control stage is completed, the system switches back to the conventional intermittent ventilation mode. The main purpose is to slowly dissipate the excess metabolic heat and moisture accumulated in the pile. As the temperature gradually drops, the fermented material naturally transitions to the maturation and aging stage until all physicochemical indicators drop to the preset standards, thereby obtaining a final fertilizer product with stable properties and qualified moisture content.
[0031] This invention provides a method for preparing fertilizer using organic waste. It has the following beneficial effects: 1. This invention employs a technical solution of spraying a composite additive containing iron-manganese bimetallic ions and sodium lignin sulfonate onto the fermentation pile during the high-temperature fermentation period. This achieves the technical effect of converting volatile free ammonia into stable macromolecular organic nitrogen in situ. Compared to existing technologies that simply add inorganic acids or porous adsorbent materials for nitrogen retention, this method utilizes the pile's own thermal energy to drive metal catalysis, causing ammonia molecules to be covalently fixed to the lignin framework. This solves the shortcomings of traditional additives, such as low reactivity in complex solid-state fermentation systems and the tendency for physically adsorbed free ammonia to undergo secondary desorption and volatilization.
[0032] 2. This invention addresses fermentation ventilation control by employing a technical solution that uses interlocked pulse start / stop of the blower to set upper and lower thresholds for intermittent oxygen concentration. This mode achieves the technical effect of extending the residence time of free ammonia in the material layer and maintaining the partial pressure of oxygen in the metal catalyst as needed. Compared to the commonly used timed and quantitative continuous ventilation or simple intermittent ventilation techniques in existing technologies, this invention constructs an alternating cycle of anoxic static retention and short-term high-pressure oxygen supplementation. This solves the problem of physical stripping and loss of ammonia caused by conventional continuous air supply, while also compensating for the low gas-liquid-solid multiphase mass transfer efficiency in solid composting systems.
[0033] 3. In terms of microenvironment monitoring, this invention employs a technical solution that utilizes an internally equipped sintered mesh filter to extract interstitial gas from the reactor core to an external oxygen analyzer for measurement. This achieves accurate measurement of oxygen partial pressure in the reaction zone and ensures the long-term stability of the analytical hardware. Compared to existing technologies that directly insert physicochemical sensor probes into the fermentation substrate, this invention implements physical isolation between the measuring components and the multiphase reaction interface. From an engineering application perspective, this solves the problem that traditional in-situ detection methods are prone to probe blockage and corrosion by high-temperature, high-humidity condensates, corrosive gases, and dust, leading to inaccurate data measurements or premature equipment damage. Attached Figure Description
[0034] Figure 1 The following is a comparison chart of the physicochemical index determination results of each embodiment and comparative example of the test examples of the present invention; wherein (a) is a bar chart of the mass fraction of water-soluble humic acid (HA) and the proportion of water-soluble organic nitrogen (WSON), and (b) is a bar chart of the ratio of humic acid to fulvic acid (HA / FA). Figure 2 This is a scatter plot of the mass percentage of the effective transition metal state in fertilizer materials in each embodiment and comparative example of the test examples of the present invention. Figure 3 The following is a comparison chart of ammonia emissions and nitrogen retention throughout the entire fermentation cycle for each embodiment and comparative example of the test examples of the present invention, wherein (a) is a bar chart of the total cumulative ammonia emissions throughout the fermentation cycle, and (b) is a bar chart of the absolute retention rate of total nitrogen in the final fertilizer product. Figure 4 The following are statistical charts showing the operational stability and anti-interference capability of the automatic control system in various embodiments and comparative examples of the test cases of the present invention. Among them, (a) is a bar chart showing the number of sensor signal distortion and drift during the core control period, and (b) is a bar chart showing the frequency of forced manual intervention. Detailed Implementation
[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.
[0036] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.
[0037] Sodium lignosulfonate (CAS No.: 8061-51-6), industrial grade, is extracted from black liquor of sulfite papermaking. Its weight-average molecular weight is 5000 Da to 50000 Da, the sulfonic acid group content is 0.5 mmol / g to 2.5 mmol / g, and the phenolic hydroxyl mass fraction is greater than or equal to 1.5%.
[0038] Ferrous sulfate heptahydrate (CAS No.: 7782-63-0), industrial grade, mass fraction greater than or equal to 90.0%.
[0039] Manganese sulfate monohydrate (CAS No.: 10034-96-5), industrial grade, mass fraction greater than or equal to 95.0%.
[0040] The organic waste substrate is prepared by mixing bulk fresh chicken manure with corn stalks crushed to a particle size of less than 5 mm at a dry basis mass ratio of 3:1. The initial carbon-nitrogen ratio of this mixed substrate is 25:1, the initial mass moisture content is 60.0%, and the initial total nitrogen dry basis mass fraction is 2.8%.
[0041] Preparation Example 1: This preparation example provides a method for preparing an aqueous solution of a composite additive, comprising the following steps: Add 3.5 kg of sodium lignosulfonate, 2.25 kg of ferrous sulfate heptahydrate and 0.6 kg of manganese sulfate monohydrate to a mixing tank equipped with a mechanical stirrer, add 25.4 kg of tap water at 25°C, and stir continuously at 200 r / min for 30 minutes to prepare a homogeneous composite auxiliary aqueous solution with a total solute mass concentration of 20.0% for later use.
[0042] Preparation Example 2: This preparation example provides a method for preparing an aqueous solution of a composite additive, comprising the following steps: Add 2.0 kg of sodium lignosulfonate, 1.5 kg of ferrous sulfate heptahydrate and 0.2 kg of manganese sulfate monohydrate to a mixing tank equipped with a mechanical stirrer, add 20.97 kg of tap water at 15°C, and stir continuously at 200 r / min for 30 minutes to prepare a homogeneous composite auxiliary aqueous solution with a total solute mass concentration of 15.0% for later use.
[0043] Preparation Example 3: This preparation example provides a method for preparing an aqueous solution of a composite additive, comprising the following steps: Add 5.0 kg of sodium lignosulfonate, 3.0 kg of ferrous sulfate heptahydrate and 1.0 kg of manganese sulfate monohydrate to a mixing tank equipped with a mechanical stirrer, add 27.0 kg of tap water at 30°C, and stir continuously at 200 r / min for 30 minutes to prepare a homogeneous composite auxiliary aqueous solution with a total solute mass concentration of 25.0% for later use.
[0044] Example 1:
[0045] This embodiment provides a method for preparing fertilizer using organic waste, including the following steps: (1) Feed the organic waste substrate containing 100kg of dry matter into the fermentation tank, pile it up, and turn on the bottom fan for continuous forced ventilation. The ventilation volume is set to 0.10m³. 3 / (min·m 3 Thermocouples are used to continuously monitor the temperature in the core area of the reactor.
[0046] (2) When the temperature of the core area of the thermocouple feedback stack rises to 60°C, start the turning machine and spray the 31.75 kg composite additive aqueous solution prepared in Example 1 evenly into the tumbling organic waste matrix and mix it evenly.
[0047] (3) After the additive spraying is completed, the continuous forced ventilation mode is switched off and the pulse oscillation control mode, which is interlocked and controlled by the gas phase oxygen concentration analyzer, is switched off for 60 hours. Interstitial gas is continuously extracted from the reactor body through a stainless steel sintered mesh filter head inserted inside the reactor body and sent to the oxygen concentration analyzer. The lower limit threshold for oxygen concentration is set at 1.5 vol%, and the upper limit threshold is set at 12.0 vol%. When the interstitial gas oxygen concentration is greater than 1.5 vol%, the blower stops, and the system is in a hypoxic static state; when the interstitial gas oxygen concentration drops to 1.5 vol%, the system triggers forced ventilation with a ventilation volume of 0.40 m³ / h. 3 / (min·m 3 The duration of a single pulse air supply is 5 minutes; when the oxygen concentration in the interstitial air rises back to 12.0 vol%, the system is forced to shut down again.
[0048] (4) After the pulse oscillation control period ends, the oxygen concentration interlock control is released and the regular intermittent ventilation is resumed, that is, ventilation for 10 minutes and rest for 50 minutes are alternated. When the temperature of the core area of the pile drops to 8°C higher than the ambient temperature and the mass moisture content drops to 28.5%, the material is discharged to obtain fertilizer product.
[0049] Example 2:
[0050] This embodiment provides a method for preparing fertilizer using organic waste, including the following steps: (1) The organic waste substrate containing 100 kg of dry matter is fed into the fermentation tank, piled up, and the bottom fan is turned on for continuous forced ventilation. The ventilation volume is set to 0.05 m³ / h. 3 / (min·m 3 Thermocouples are used to continuously monitor the temperature in the core area of the reactor.
[0051] (2) When the temperature of the core area of the thermocouple feedback stack rises to 55°C, start the turning machine and spray the 24.67 kg composite additive aqueous solution prepared in Example 2 evenly into the tumbling organic waste matrix and mix it evenly.
[0052] (3) After the additive spraying is completed, the continuous forced ventilation mode is switched off and the pulse oscillation control mode, which is interlocked and controlled by the gas phase oxygen concentration analyzer, is switched off for 48 hours. The interstitial gas in the reactor body is continuously extracted through a stainless steel sintered mesh filter head inserted inside the reactor body and sent to the oxygen concentration analyzer. The lower limit threshold for oxygen concentration is set at 1.0 vol%, and the upper limit threshold is set at 10.0 vol%. When the interstitial gas oxygen concentration is greater than 1.0 vol%, the blower stops, and the system is in a state of oxygen deficiency and quiescence. When the interstitial gas oxygen concentration drops to 1.0 vol%, the system triggers forced ventilation with a ventilation volume of 0.30 m³ / h. 3 / (min·m 3 The duration of a single pulse air supply is 3 minutes; when the oxygen concentration in the interstitial air rises back to 10.0 vol%, the system is forced to shut down again.
[0053] (4) After the pulse oscillation control period ends, the oxygen concentration interlock control is released and the regular intermittent ventilation is resumed, that is, ventilation for 10 minutes and rest for 50 minutes are alternated. When the temperature of the core area of the pile drops to 5°C higher than the ambient temperature and the mass moisture content drops to 25.0%, the material is discharged to obtain fertilizer product.
[0054] Example 3:
[0055] This embodiment provides a method for preparing fertilizer using organic waste, including the following steps: (1) The organic waste substrate containing 100 kg of dry matter is fed into the fermentation tank, piled up, and the bottom fan is turned on for continuous forced ventilation. The ventilation volume is set to 0.15 m³ / h. 3 / (min·m 3 Thermocouples are used to continuously monitor the temperature in the core area of the reactor.
[0056] (2) When the temperature of the core area of the thermocouple feedback stack rises to 65°C, start the turning machine and spray the 36.0 kg composite additive aqueous solution prepared in Example 3 evenly into the tumbling organic waste matrix and mix it evenly.
[0057] (3) After the additive spraying is completed, the continuous forced ventilation mode is switched off and the pulse oscillation control mode, which is interlocked and controlled by the gas phase oxygen concentration analyzer, is switched off for 72 hours. The interstitial gas in the reactor body is continuously extracted through a stainless steel sintered mesh filter head inserted inside the reactor body and sent to the oxygen concentration analyzer. The lower limit threshold for oxygen concentration is set at 2.0 vol%, and the upper limit threshold is set at 15.0 vol%. When the interstitial gas oxygen concentration is greater than 2.0 vol%, the blower stops, and the system is in a hypoxic static state; when the interstitial gas oxygen concentration drops to 2.0 vol%, the system triggers forced ventilation with a ventilation volume of 0.50 m³ / h. 3 / (min·m 3 The duration of a single pulse air supply is 10 minutes; when the oxygen concentration in the interstitial air rises back to 15.0 vol%, the system is forced to shut down again.
[0058] (4) After the pulse oscillation control period ends, the oxygen concentration interlock control is released and the regular intermittent ventilation is resumed, that is, ventilation for 10 minutes and rest for 50 minutes are alternated. When the temperature of the core area of the pile drops to 10°C higher than the ambient temperature and the mass moisture content drops to 29.5%, the material is discharged to obtain fertilizer product.
[0059] Example 4:
[0060] This embodiment provides a method for preparing fertilizer using organic waste, including the following steps: (1) Feed the organic waste substrate containing 100kg of dry matter into the fermentation tank, pile it up, and turn on the bottom fan for continuous forced ventilation. The ventilation volume is set to 0.10m³. 3 / (min·m 3 Thermocouples are used to continuously monitor the temperature in the core area of the reactor.
[0061] (2) When the temperature of the core area of the thermocouple feedback stack rises to 60°C, start the turning machine and spray the 31.75 kg composite additive aqueous solution prepared in Example 1 evenly into the tumbling organic waste matrix and mix it evenly.
[0062] (3) After the additive spraying is completed, the continuous forced ventilation mode is switched off and the pulse oscillation control mode, which is interlocked and controlled by the gas phase oxygen concentration analyzer, is switched off for 60 hours. Interstitial gas in the reactor body is continuously extracted through a stainless steel sintered mesh filter head inserted inside the reactor body and sent to the oxygen concentration analyzer. The lower limit threshold for oxygen concentration is set at 1.5 vol%, and the upper limit threshold is set at 12.0 vol%. When the interstitial gas oxygen concentration is greater than 1.5 vol%, the blower stops, and the system is in a hypoxic static state; when the interstitial gas oxygen concentration drops to 1.5 vol%, the system triggers forced ventilation with a ventilation volume of 0.45 m³ / h. 3 / (min·m 3The duration of a single pulse air supply is 8 minutes; when the oxygen concentration in the interstitial air rises back to 12.0 vol%, the system is forced to shut down again.
[0063] (4) After the pulse oscillation control period ends, the oxygen concentration interlock control is released and the regular intermittent ventilation is resumed, that is, ventilation for 10 minutes and rest for 50 minutes are alternated. When the temperature of the core area of the pile drops to 8°C higher than the ambient temperature and the mass moisture content drops to 28.0%, the material is discharged to obtain fertilizer product.
[0064] Comparative Example 1: Compared to Example 1, the difference is that no composite additive aqueous solution was added, and within 60 hours after the temperature in the reactor core region rose to 60°C, the pulse oscillation control mode was not switched to, but instead remained at 0.10m. 3 / (min·m 3 ) continuous forced ventilation, the rest are the same.
[0065] Comparative Example 2: Compared with Example 1, the difference is that sodium lignosulfonate was not added to the sprayed composite adjuvant aqueous solution; that is, the solute consisted only of 2.25 kg of ferrous sulfate heptahydrate and 0.6 kg of manganese sulfate monohydrate, while the rest were the same.
[0066] Comparative Example 3: Compared with Example 1, the difference is that no manganese sulfate monohydrate was added to the sprayed composite additive aqueous solution, that is, the solute consisted only of 3.5 kg sodium lignosulfonate and 2.25 kg ferrous sulfate heptahydrate, and the rest were the same.
[0067] Comparative Example 4: Compared to Example 1, the difference lies in that: after the temperature in the reactor core region rose to 60°C and the composite additive aqueous solution was sprayed, the pulse oscillation control mode was not switched to, but instead remained at 0.10m. 3 / (min·m 3 The continuous forced ventilation lasted for 60 hours, and all other aspects were the same.
[0068] Comparative Example 5: Compared with Example 1, the difference is that the composite additive aqueous solution is sprayed and mixed at once during the stacking process in step (1), instead of being added when the temperature in the core area of the stack rises to 60°C in step (2). The rest are the same.
[0069] Comparative Example 6: Compared with Example 1, the difference is that in step (3), the interstitial gas is not extracted to measure the oxygen concentration. Instead, the industrial liquid phase ORP probe is directly inserted into the reactor body. The lower limit threshold of ORP is set to -150mV and the upper limit threshold is +50mV to control the start-stop interlock of the blower. All other aspects are the same.
[0070] Test Example 1: Test objective: To verify the mechanism of quinone-amine nucleophilic addition and abiotic humification macromolecular polymerization that occurs under the coupling of composite additives and pulsed oxygen supply process.
[0071] Test steps: 1. Sample collection and pretreatment: After the cooling and aging period of each embodiment and comparative example is over and the material is discharged, 200g of the final fertilizer product is weighed using a multi-point mixed sampling method. After being naturally air-dried at room temperature, the product is physically crushed, ground, and passed through a 100-mesh sieve for later use.
[0072] 2. Extraction and determination of humic acid (HA) and fulvic acid (FA): Weigh 2.00 g of the prepared pulverized sample and place it in a centrifuge tube. Add 50 mL of a mixed extraction solution containing 0.1 mol / L sodium hydroxide and 0.1 mol / L sodium pyrophosphate. Extract for 24 hours in a constant temperature shaking oven at 25℃. Then centrifuge to obtain the supernatant of the humic extract. Acidify the extract with 0.5 mol / L dilute sulfuric acid to adjust the pH to 1.0. After standing for 12 hours, centrifuge again. The precipitate at the bottom is humic acid (HA), and the supernatant is fulvic acid (FA). The total carbon content of both is determined by potassium dichromate titration method. Based on this, the mass fraction of water-soluble humic acid is calculated, and the ratio of humic acid to fulvic acid is calculated.
[0073] 3. Determination of the proportion of water-soluble organic nitrogen (WSON): Weigh 5.00g of the pulverized sample and place it in an Erlenmeyer flask. Add 50mL of deionized water and extract by vigorous shaking at room temperature for 2 hours. Centrifuge and filter to obtain the aqueous extract. Determine the total dissolved nitrogen (TDN) concentration in the aqueous extract using alkaline potassium persulfate digestion combined with ultraviolet spectrophotometry. At the same time, determine the dissolved inorganic nitrogen (DIN, including ammonium nitrogen and nitrate nitrogen) concentration in the aqueous extract using a continuous flow analyzer. Calculate the content of water-soluble organic nitrogen (WSON) by the difference between total dissolved nitrogen and dissolved inorganic nitrogen, and calculate its mass percentage of total dissolved nitrogen.
[0074] The test data is shown in Table 1.
[0075] Table 1: Results of Physicochemical Indicators of Final Fertilizer Product ; Conclusion: Based on Table 1 and Figure 1The data shows that the mass fraction of water-soluble humic acid and the proportion of water-soluble organic nitrogen in the final fertilizer product of Example 1 showed a substantial increase compared to Comparative Example 1. Traditional aerobic fermentation, due to its over-reliance on the slow humification pathway of indigenous microorganisms, often results in a large amount of free ammonia being lost through volatilization during high-temperature periods, leading to extremely low efficiency in converting free inorganic nitrogen into bound organic nitrogen. The test results of this invention confirm the underlying chemical reaction logic. By precisely intervening in the sodium lignin sulfonate and iron-manganese bimetallic system during the peak release period of free ammonia at 55°C to 65°C, a purely chemical humification channel independent of biological metabolism was successfully constructed within the reaction matrix. Driven by the thermal energy of the pile, high-valence metal ions capture electrons from the phenolic hydroxyl groups of lignin and generate highly reactive quinone groups. These electrophilic groups directly launch nucleophilic attacks on free ammonia at the porous solid-liquid interface, resulting in Michael addition reactions, which firmly fix the inorganic ammonia that was originally easily lost with the airflow into stable nitrogen-containing aromatic heterocyclic macromolecules.
[0076] The effective operation of this multiphase catalytic system is highly dependent on the integrity of the electron transport chain and the precise matching of process nodes. In Comparative Example 3, where manganese ions were removed, all humification indicators showed a significant decline. During the initial microenvironment monitoring of the process, we observed that the single iron-mediated system was easily limited by hydroxyl complexation in the weakly alkaline fermentation substrate. The obstructed electron transport led to a severe lag in the quinone conversion rate of the polyphenol substrate during the anoxic settling period, preventing the reaction system from capturing sufficient ammonia within the short reaction window. Deviations in the timing of addition also caused the overall failure of the catalytic system. In Comparative Example 5, the composite additive was mixed into the substrate all at once during the initial stack setup. The metal ions were prematurely exposed to the high concentration of low-grade fatty acids accumulated in the early fermentation stage at room temperature, resulting in passivation precipitation. This meant that by the time the stack entered the high-temperature period requiring large-scale capture of free ammonia, the catalyst had already lost most of its activity reserves.
[0077] The gas-phase interlock control strategy provides the macroscopic physical microenvironment necessary for this chemical system to occur. Comparative Example 4, with a complete catalyst formulation, still uses conventional continuous forced ventilation. The strong gas-solid mass transfer forcefully strips ammonia from the matrix system before chemical addition occurs, confirming that chemical nitrogen fixation relies on sufficient residence time provided by the anoxic settling period. In engineering verification, Comparative Example 6 uses a conventional liquid-phase ORP probe directly inserted into the sludge material for control. Biofilm adhesion and inorganic salt scaling on the probe surface caused frequent deadlocks in the later stages of testing, and the disordered air supply sequence completely disrupted the alternating rhythm of anoxic and oxygen-enriched processes. This solution, by extracting interstitial gas to measure the partial pressure of pure gas-phase oxygen, avoids the physical interference of the harsh solid-state fermentation environment on the sensing elements, ensuring that the alternating cycle of anoxic settling for ammonia capture and oxygen-enriched pulse regeneration can be accurately reproduced in a 10,000-ton fermentation tank.
[0078] Test Example 2: Test objective: To demonstrate that in a weakly alkaline composting environment, the iron-manganese bimetallic compound retains its catalytic activity through complexation with lignin and does not transform into an ineffective residual precipitate.
[0079] Test steps: 1. Materials from the core area of the stack at the end of the pulse control period (i.e., before the system is about to enter the cooling and aging period) in Examples 1 to 4 and Comparative Examples 2 to 6 were extracted as test subjects. Comparative Example 1 was not included in this test because no metal additives were added. The collected materials were placed in a vacuum freeze dryer at -60°C for 48 hours, then ground with an agate mortar and passed through a 200-mesh nylon sieve.
[0080] 2. The absolute mass fractions of total iron and total manganese in each group of solid powder samples were determined by microwave digestion combined with inductively coupled plasma atomic emission spectrometry (ICP-AES) and used as the baseline denominator data for subsequent calculations of proportions.
[0081] 3. The Tessier continuous chemical extraction method was used to fractionate and separate the metal speciation in the sample. 1.000 g of powdered sample was weighed and placed in a polytetrafluoroethylene centrifuge tube. 8 mL of 1.0 mol / L magnesium chloride solution was added, and the mixture was continuously shaken at room temperature for 1 hour to extract exchangeable metals. After centrifuging the supernatant, 8 mL of 0.5 mol / L sodium acetate solution adjusted to pH 5.0 was added to the residue, and the mixture was continuously shaken for 5 hours to extract weakly acidic metals. After centrifugation again, 3 mL of 0.02 mol / L nitric acid and 5 mL of 30% hydrogen peroxide were added to the residue, and the mixture was digested in an 85°C water bath for 2 hours to extract organically bound metals.
[0082] 4. Collect the supernatants obtained from the above three extraction steps, and determine the concentrations of iron and manganese ions using inductively coupled plasma atomic emission spectrometry (ICP-AES). Define the sum of the masses of metals in the exchangeable and organically bound states as the effective transition metal, and calculate its percentage of the corresponding total metal mass in the material.
[0083] The test data is shown in Table 2.
[0084] Table 2: Results of determination of the mass percentage of available transition metals in total metals ; Conclusion: Based on Table 2 and Figure 2The data shows that iron and manganese in the example group maintained an effective state ratio of over 80% at the end of the high-temperature period of aerobic fermentation, while the data in Comparative Example 2 showed a sharp drop. Conventional aerobic compost substrates typically exhibit a weakly alkaline porous medium with a pH between 7.5 and 8.5 during the high-temperature period. This physicochemical environment is extremely unfriendly to free transition metals. When inorganic iron and manganese salts are simply added to the system, the metal ions undergo rapid hydrolysis and form highly crystalline hydroxide or oxide precipitates. Once in the residual phase region, the metal atoms are bound by the crystal lattice, thus completely losing their ability to act as electron shuttle mediators. In our preliminary material screening, we observed that sodium lignin sulfonate not only serves as a carbon skeleton acceptor for subsequent nucleophilic addition reactions, but its densely distributed sulfonic acid groups and phenolic hydroxyl groups on its molecular chain are also excellent multidentate ligands. These groups can undergo strong coordination complexation with iron and manganese ions in the micro-aqueous film at the solid-liquid interface, forming large molecular water-soluble complexes with large steric hindrance, thereby significantly inhibiting the thermodynamic transformation of metal ions into the inorganic precipitate phase.
[0085] The maintenance of this homogeneous activity is strongly coupled with the selection of the process trigger point. Comparative Example 5, which incorporated a prepared composite additive solution in a single batch during the initial stage of composting at room temperature, showed a significant reduction in the proportion of available metals to approximately 30%. The initial stage of composting fermentation is often accompanied by intense anaerobic and facultative anaerobic biodegradation processes, resulting in the rapid accumulation of large amounts of lower fatty acids, primarily acetic and butyric acids. Simultaneously, long-lasting anaerobic zones easily form within the material. Under these extreme microenvironments, even with lignin chelation protection, bimetallic complexes are gradually passivated or precipitated by combining with other insoluble inorganic anions during the prolonged heating period. This invention precisely locks the addition point within the temperature range of 55°C to 65°C, effectively avoiding the severe chemical interference in the early stages. This allows the catalyst system to directly intervene in the core reaction window where free ammonia release is most concentrated and thermal driving force is strongest, maximizing the utilization of the initial high-activity state of metal ions.
[0086] Highly active available metal reserves are the material basis for the operation of the entire abiotic humification electron transport chain. The available metal data in Comparative Example 4 showed a certain degree of decline, indicating that the sustained high oxygen partial pressure caused by long-term, single, continuous forced ventilation accelerates the irreversible aging and crystallization of complexed metals. The oxygen concentration interlocked pulse oscillation mode adopted in this scheme enables high-frequency switching between anoxic reduction and oxygen-rich oxidation in the reactor microenvironment. This potential oscillation effectively maintains the reversible cycle of metal ions between different valence states, avoiding activity decay caused by unidirectional oxidation. Comparative Example 6, due to contamination and deadlock of the liquid phase probe leading to disordered start-up and shutdown, disrupted internal gas-phase mass transfer, ultimately exhibiting an abnormal drop in the catalyst's available metal state. Sufficient available metal ensures that during each brief oxygen-rich pulse period, it is rapidly oxidized into highly electron-withdrawing high-valence manganese and iron ions, which then efficiently extract electrons from the lignin polyphenol substrate to generate quinone groups during the subsequent anoxic settling period, providing a continuous source of electrophilic reaction sites for the subsequent nucleophilic addition reaction of free ammonia.
[0087] Test Example 3: Test objective: To visually quantify the superior nitrogen retention effect of this invention in solving the core technical problem of severe ammonia volatilization in aerobic composting.
[0088] Test steps: 1. This test covers the complete fermentation cycle of Examples 1 to 4 and Comparative Examples 1 to 6. A sealed gas duct was connected to the exhaust port at the top of each fermentation tank to guide the exhaust gas to a multi-stage absorption bottle containing 0.05 mol / L sulfuric acid absorbent. The exhaust gas was continuously captured for 24 hours throughout the entire stacking, high-temperature and cooling aging stages, and the absorbent was replaced every 12 hours.
[0089] 2. After collecting sulfuric acid absorption liquid from each time period and adjusting the volume, the concentration of ammonium ions in the absorption liquid was determined by Nessler's reagent spectrophotometry. The total absolute mass of free ammonia discharged throughout the entire cycle was obtained by integration and conversion. This mass was then divided by the total mass of the initial dry matter added during the pile construction to calculate the total cumulative ammonia emissions during the entire fermentation cycle. The unit is recorded as g / kg dry basis.
[0090] 3. At the initial stage of composting and at the end of fermentation, solid material samples were collected from each compost pile using a multi-point grid method. After freeze-drying and pulverization, the total nitrogen mass fraction in the material was determined using the Kjeldahl method combined with a fully automated Kjeldahl nitrogen analyzer. Combining the changes in the total dry weight of the initial and final materials, the ratio of the absolute mass of total nitrogen in the final fertilizer product to the absolute mass of total nitrogen in the initial state was calculated using the law of conservation of mass, thus obtaining the absolute retention rate of total nitrogen relative to the initial state.
[0091] The test data is shown in Table 3.
[0092] Table 3: Results of Cumulative Ammonia Emissions and Absolute Retention Rate of Total Nitrogen over the Entire Cycle ; Conclusion: Based on Table 3 and Figure 3 According to the data, the total ammonia emissions in Example 1 were suppressed to an extremely low level of 2.14 g / kg dry basis, and the total nitrogen retention rate exceeded 86%. This nitrogen interception efficiency is difficult to achieve in conventional aerobic composting. The conventional uninterrupted Comparative Example 1 revealed an extremely serious nitrogen loss problem, with more than half of the nitrogenous substances escaping into the atmosphere as free ammonia during the high-temperature period of rapid proliferation of thermophilic microorganisms. In our mechanism verification, we found that simply introducing iron-manganese bimetals into the system could not block this physical volatilization process. In Comparative Example 2, even without sodium lignin sulfonate, the ammonia emissions were still as high as 13.41 g / kg dry basis. Free ammonia molecules have a strong tendency to volatilize; the weak polarization effect of metal ions alone cannot bind them to the porous solid phase at the macroscopic level. An electrophilic acceptor capable of accepting their lone pair electrons must exist in the reaction system. Under the electron shuttle catalysis of bimetals, the lignin polyphenol skeleton is transformed into a highly active quinone group, providing a large number of carbon skeleton grafting sites for free ammonia, so that the originally volatile inorganic nitrogen is completely inserted into the stable aromatic heterocyclic macromolecular network through Michael addition.
[0093] The presence of electrophilic acceptors in the formulation only establishes a potential pathway for chemical reactions; the actual occurrence of this abiotic humification process remains constrained by macroscopic mass transfer and microenvironmental kinetics. Comparative Example 4, which eliminated the shutdown and static setting process, possessed a perfect additive formulation, but its ammonia emissions were almost identical to the completely blank control group, with a nitrogen loss rate approaching 53%. Under the strong convective airflow of continuous forced ventilation, the gas film thickness at the solid-liquid interface was extremely compressed. The physical stripping rate of ammonia desorbing from the liquid phase and diffusing into the gas phase was far greater than the rate of its nucleophilic addition with quinone groups. Continuous oxygen supply also disrupted the potential conditions for metal ion reduction and regeneration. By setting a lower limit for oxygen concentration to force the fan to shut down, the system created an absolutely still and highly oxygen-deficient closed microenvironment inside the reactor, allowing free ammonia to accumulate to extremely high local concentrations in the gaps, thus providing sufficient reaction residence time and kinetic potential energy to drive the complete completion of the macromolecular coupling reaction.
[0094] This precise control over the reaction microenvironment profoundly determines the actual emission reduction effect at the engineering site, and the anti-interference capability of the sensor acquisition end is directly related to the survival of the chemical control logic. Comparative Example 6, controlled using a traditional liquid-phase insertion ORP probe, showed a significant deterioration trend, with the total nitrogen retention rate falling back to around 63%. In our engineering tests, we frequently observed that high-temperature, high-humidity material slurry rich in viscous protein substrates rapidly forms a dense scale layer on the ORP electrode surface, causing the instrument's feedback potential value to stagnate in the heavily reduced range for an extended period without recovery. This signal deadlock triggered an abnormally long-term shutdown of the blower, followed by localized excessive anaerobic denitrification that consumed the previously accumulated nitrate nitrogen as nitrogen gas. This solution uses the method of extracting interstitial gas to measure oxygen partial pressure, completely separating the sensitive sensing element from the turbid solid-liquid multiphase flow. The inherent mass transfer hindrance between the gas phase oxygen concentration and the dissolved oxygen in the liquid phase of the material forms an excellent mapping relationship, which enables the alternating rhythm of oxygen replenishment pulse and oxygen capture to be executed accurately without being disturbed by physical pollution, ultimately ensuring efficient nitrogen preservation operation throughout the entire cycle.
[0095] Test Example 4: Test objective: To specifically verify the engineering reliability and resistance to physical failure of the interlocking control strategy for intermittent oxygen concentration mapping in a high-temperature multiphase fermentation environment.
[0096] Test steps: 1. Examples 1 to 4, which were within the core pulse oscillation control period, and Comparative Example 6, which used a direct-insertion liquid phase ORP probe, were selected as the key monitoring targets. During the 48 to 72-hour period after the system switched to the upper and lower limit threshold control mode set by oxygen concentration or ORP, the background high-frequency data recording module inside the programmable logic controller was activated to continuously store the analog electrical signals fed back by the sensor with a sampling period of 1 minute.
[0097] 2. Set thresholds for judging sensor signal drops or severe distortion drift. For gas phase oxygen concentration sensors, a signal distortion is defined as a sudden change of more than 5% in the oxygen partial pressure reading between two consecutive sampling cycles, or a reading remaining unchanged for up to 2 hours under continuous fan operation. For liquid phase ORP probes that directly contact materials, a signal deadlock or distortion drift is defined as a sudden rise or fall of more than 100mV in the detected potential within 1 minute, or a signal deadlock or distortion drift as the probe feedback value remains locked in the severe reduction potential range for 3 hours after the system has triggered forced ventilation. Count the total number of distortions occurring in each group throughout the entire monitoring period.
[0098] 3. Record the frequency of manual interventions required to maintain the normal operation of the automatic control logic during the monitoring period. When the system main control interface issues a sensor feedback failure alarm or observes that the fan start-stop sequence seriously violates the process settings, on-site engineers must intervene and perform a complete set of maintenance actions, including removing the probe, physically cleaning the surface of dirt and crystallized salt, recalibrating with standard solution, and reinserting and fixing it. Summarize the total number of maintenance operations for each test group during the monitoring period.
[0099] The test data is shown in Table 4.
[0100] Table 4: Statistical Results of Sensor Signal Distortion and Frequency of Human Intervention During the Core Control Period ; Conclusion: Based on Table 4 and Figure 4 The data from Comparative Example 6 shows that within a short core pulse control period of only a few tens of hours, there were as many as 27 instances of severe signal distortion. Engineers were forced to perform 14 manual interventions involving removal, cleaning, and recalibration. Such an extremely high maintenance frequency is completely impractical for industrial continuous production on a scale of tens of thousands of tons. When high-temperature aerobic fermentation enters the core region above 55°C, the material system not only contains extremely high concentrations of viscous depolymerizing proteins and humic acid precursors, but also experiences significant evaporation and condensation of water. When a conventional ORP probe is directly inserted into this extremely muddy and violently physicochemically evolving solid-liquid multiphase medium, the probe's platinum sensing end face is densely enveloped by an organic-rich biofilm and carbonate crystals within tens of minutes. We have frequently confirmed this phenomenon during past on-site equipment commissioning. This thick, dense physical barrier completely severs the electron exchange channel between the probe and the bulk liquid phase, causing the sensor's feedback potential value to remain stagnant in the severely reduced range for a long time. No matter how much forced oxygen supply from the fan, it cannot trigger the upper limit shutdown threshold, ultimately causing the preset alternating pulse sequence to completely collapse.
[0101] The example group, by completely eliminating direct liquid-phase contact measurement, eradicated the engineering pain point of sensor element contamination and scaling at the physical structure level. The data clearly demonstrates the system's high operational resilience under harsh environments, with the vast majority of examples achieving autonomous and stable operation with zero human intervention during the testing period. The stainless steel sintered mesh filter head inserted inside the reactor body serves only as a gas phase channel. The negative pressure of an external air pump forcibly strips free gas from the material pores out of the reaction matrix and delivers it to the optical oxygen concentration analyzer located in a clean control cabinet outside the tank. The sensor probe is always in a relatively clean gas phase airflow containing only water vapor, completely avoiding direct erosion from highly adhesive solid particles and large liquid molecular contaminants, thus ensuring long-term high-fidelity output of the measurement signal. Occasional, very rare data fluctuations are mainly due to the instantaneous accumulation of condensate inside the air extraction pipeline, which can usually be quickly restored by the system's built-in timed automatic backflushing program without on-site personnel intervention.
[0102] The physical path of gas-liquid separation perfectly supports the underlying bimetallic catalytic humification chemical mechanism. Its core lies in the inherent resistance to gas-liquid mass transfer at the solid-liquid interface, which forms an excellent physical mapping bridge. The bimetallic oxidation regeneration and quinone conversion reactions of lignin polyphenols occur within the tiny water film encapsulating the surface of solid particles. Due to the significant mass transfer attenuation caused by oxygen molecules penetrating this liquid film, a stable hysteresis mapping relationship is formed between the macroscopic oxygen concentration in the gas phase and the microscopic redox potential of the liquid film. When the sensor measures that the extracted macroscopic interstitial gas oxygen concentration drops to a low threshold of 1.5 vol%, the mass transfer hindrance ensures that the deep interior of the liquid film is in an absolutely anoxic state. At this point, the extremely low ORP environment perfectly meets the kinetic conditions required for the large-scale nucleophilic addition of free ammonia to newly generated quinone groups. This scheme utilizes this precise gas-phase threshold mapping to accurately replicate the potential oscillation rhythm necessary for complex macromolecular coupling reactions in the liquid phase, while avoiding the fatal flaws of physical probe contamination.
[0103] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for preparing fertilizer using organic waste, characterized in that, Includes the following steps: (1) The organic waste substrate is fed into the fermentation tank for stacking, the bottom fan is turned on for continuous forced ventilation, and the temperature of the core area of the stack is monitored; (2) When the temperature of the core area of the pile rises to the preset high temperature threshold, the composite additive aqueous solution is sprayed evenly into the organic waste matrix and mixed evenly; the composite additive aqueous solution contains sodium lignosulfonate, ferrous sulfate heptahydrate and manganese sulfate monohydrate; (3) After the composite additive aqueous solution is sprayed, the continuous forced ventilation mode is cut off and switched to the pulse oscillation control mode controlled by the gas phase oxygen concentration analyzer; the oxygen concentration is measured by extracting the interstitial gas of the stack and sending it into the oxygen concentration analyzer, and the start and stop of the bottom fan is controlled according to the preset upper and lower limit thresholds of the interstitial gas oxygen concentration. (4) After the control period of the pulse oscillation control mode ends, the interlock control is released, intermittent ventilation is restored, and fertilizer products are obtained when the temperature and moisture content of the core area of the pile drop to the preset discharge standard.
2. The method for preparing fertilizer using organic waste according to claim 1, characterized in that, In step (1), the organic waste substrate is prepared by mixing fresh chicken manure and corn stalks crushed to a particle size of less than 5 mm at a dry basis mass ratio of 2-4:
1. The initial carbon-nitrogen ratio of the organic waste substrate is 20:1-30:1, and the initial mass moisture content is 55.0%-65.0%.
3. The method for preparing fertilizer using organic waste according to claim 1, characterized in that, The aqueous solution of the composite additive is prepared from the following raw materials in parts by weight: 2.0-5.0 parts sodium lignosulfonate, 1.5-3.0 parts ferrous sulfate heptahydrate, 0.2-1.0 parts manganese sulfate monohydrate, and 20.97-27.0 parts water.
4. The method for preparing fertilizer using organic waste according to claim 3, characterized in that, The sodium lignosulfonate has a weight-average molecular weight of 5000 Da to 50000 Da, a sulfonic acid group content of 0.5 mmol / g to 2.5 mmol / g, and a phenolic hydroxyl group mass fraction greater than or equal to 1.5%.
5. The method for preparing fertilizer using organic waste according to claim 1, characterized in that, The preparation steps of the composite auxiliary aqueous solution are as follows: sodium lignosulfonate, ferrous sulfate heptahydrate and manganese sulfate monohydrate are put into a mixing tank equipped with mechanical stirring, water at a temperature of 15℃-30℃ is added, and the mixture is stirred continuously at a speed of 200r / min for 30 minutes to prepare a homogeneous aqueous solution with a total solute mass concentration of 15.0%-25.0%.
6. The method for preparing fertilizer using organic waste according to claim 1, characterized in that, In step (1), thermocouples are used to monitor the temperature of the core area of the reactor, and the ventilation volume of the continuous forced ventilation is set to 0.05 m³ / s. 3 / (min·m 3 -0.15m 3 / (min·m 3 ).
7. The method for preparing fertilizer using organic waste according to claim 1, characterized in that, In step (2), the preset high temperature threshold is 55℃-65℃; the absolute mass of the sprayed composite additive aqueous solution in the organic waste matrix per 100kg of dry matter is 24.67kg-36.0kg.
8. The method for preparing fertilizer using organic waste according to claim 1, characterized in that, The specific parameter settings in step (3) are as follows: The lower limit threshold for interstitial oxygen concentration is set at 1.0 vol%-2.0 vol%, and the upper limit threshold is set at 10.0 vol%-15.0 vol%. When the oxygen concentration in the interstitial air exceeds the upper limit threshold, the bottom fan stops. When the oxygen concentration in the interstitial air drops to the lower threshold, forced ventilation is triggered, with a ventilation volume of 0.30 m³. 3 / (min·m 3 -0.50m 3 / (min·m 3 The duration of a single pulse air supply is 3 to 10 minutes; When the oxygen concentration in the interstitial gas rises back to the upper limit threshold, the system is forced to shut down again. The control period of the pulse oscillation control mode lasts for 48 to 72 hours.
9. The method for preparing fertilizer using organic waste according to claim 1, characterized in that, In step (3), the stainless steel sintered mesh filter head inserted into the reactor body is used to continuously extract the interstitial gas of the reactor body and send it into the gas phase oxygen concentration analyzer.
10. The method for preparing fertilizer using organic waste according to claim 1, characterized in that, In step (4), the intermittent ventilation alternates between 10 minutes of ventilation and 50 minutes of rest; the preset discharge standard is: the temperature of the core area of the pile drops to 5℃-10℃ higher than the ambient temperature, and the mass moisture content drops to 25.0%-29.5%.