Segmented temperature control fermentation organic fertilizer and preparation method thereof

Abstract

The application discloses a kind of segmented temperature control fermentation organic fertilizer and preparation method thereof, it is related to organic waste resource utilization technical field;The method comprises: after organic waste raw materials pretreatment, place in fermentation device;Sequentially execute the segmented temperature control fermentation of first mesophilic stage, high temperature stage and second mesophilic stage;In first mesophilic stage, with liquid deep layer directional injection mode, to the interior of pile body inoculates the matured bacterial inoculant comprising cellulose degradation bacteria and lignin degradation bacteria;Between first mesophilic stage and high temperature stage, between high temperature stage and second mesophilic stage, according to the automatic switching temperature stage of real-time detection fermentation substrate physicochemical parameter;Intermittent positive pressure oxygen supply and natural convection ventilation are alternately operated in high temperature stage, form aerobic facultative anaerobic alternate microenvironment;The application realizes intelligent self-adaptive control of fermentation process, significantly shortens fermentation period, improves the degradation rate and rot degree of organic matter, and enriches the high-activity functional flora simultaneously.

Description

Technical Field

[0001] This invention relates to the field of organic waste resource utilization technology, specifically a segmented temperature-controlled fermentation organic fertilizer and its preparation method. Background Technology

[0002] The essence of organic fertilizer fermentation is to utilize microbial community succession to achieve the mineralization and humification of organic matter. While existing segmented temperature control technologies divide the temperature range, the switching between each stage relies entirely on manually set timeframes, failing to respond to changes in the actual decomposition state of the fermentation substrate. This leads to a disconnect between microbial metabolic activity and substrate degradation kinetics. Furthermore, traditional high-temperature stages typically employ continuous forced ventilation to maintain an aerobic environment, but this method excessively consumes readily degradable carbon sources and inhibits the activity of lignin-degrading fungi such as basidiomycetes, resulting in significant residues of recalcitrant components such as cellulose and lignin.

[0003] To address the aforementioned issues, the shortcomings of existing technical solutions are that they cannot adaptively adjust the fermentation stage according to the real-time biochemical state of the fermentation substrate, the oxygen supply mode during the high-temperature period is too singular to induce the synthesis and expression of lignin-degrading enzymes, and the crude inoculation method of the microbial agent results in low survival rate and uneven distribution of functional microorganisms, thus limiting the degradation efficiency of organic matter. Therefore, in order to address the above technical problems, it is urgent to develop a more suitable segmented temperature-controlled fermentation organic fertilizer and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a segmented temperature-controlled fermentation organic fertilizer and its preparation method, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing segmented temperature-controlled fermentation organic fertilizer. Step 1: Pre-treat the organic waste raw materials by adjusting their moisture content, carbon-nitrogen ratio, pH value and porosity to a range suitable for microbial growth to obtain a fermentation substrate; Step 2: Place the fermentation substrate into the fermentation device and execute the first mesophilic fermentation stage. Control the temperature of the fermentation substrate to be maintained within the optimal growth temperature range of the thermophilic bacteria. In the first mesophilic fermentation stage, inoculate the fermentation substrate with a composting agent by liquid deep directional injection. The composting agent contains at least one microbial strain with cellulose degradation ability and at least one microbial strain with lignin degradation ability. Step 3: During the first mesophilic fermentation stage, at least one physicochemical parameter of the fermentation substrate is continuously or intermittently monitored in real time. When the physicochemical parameter reaches a first preset threshold, the fermentation device is automatically triggered to switch to the high-temperature fermentation stage. The temperature of the fermentation substrate is controlled to be maintained within the optimal growth temperature range of thermophilic bacteria. In the high-temperature fermentation stage, a strategy of alternating intermittent positive pressure oxygen supply and natural convection ventilation is adopted to form an alternating aerobic and facultative anaerobic microenvironment inside the fermentation substrate. Step 4: During the high-temperature fermentation stage, the physicochemical parameters are continuously monitored. When the physicochemical parameters reach the second preset threshold, the fermentation device is automatically switched to the second mesophilic fermentation stage to control the temperature of the fermentation substrate to be maintained within the optimal growth temperature range of facultative anaerobic fungi. Step 5: Continuously monitor the physicochemical parameters until they reach the fermentation termination threshold, and end the segmented temperature-controlled fermentation process.

[0006] As a further aspect of the present invention: the physicochemical parameters are selected from at least one of volatile fatty acid concentration or pH value; the first preset threshold is the range where the volatile fatty acid concentration decreases to 30% to 50% of its initial concentration, or the pH value rises to the range of 8.0 to 8.5; the second preset threshold is the range where the volatile fatty acid concentration decreases again to 20% to 40% of the peak concentration reached in the high-temperature fermentation stage, or the pH value falls back and stabilizes in the range of 7.5 to 8.0.

[0007] As a further aspect of the present invention, the strategy of alternating intermittent positive pressure oxygen supply and natural convection ventilation specifically includes: supplying heated or unheated air to the fermentation substrate with a forced ventilation device for 3 to 8 minutes, stopping the forced ventilation and opening the exhaust port of the fermentation device to utilize natural convection for ventilation for 10 to 30 minutes, repeating the alternating cycle of forced ventilation and natural convection ventilation, so that the oxygen concentration in the deep region of the fermentation substrate exhibits periodic fluctuations within the range of 5% to 15%.

[0008] As a further aspect of the present invention, the method of liquid deep directional injection is as follows: the fermentation agent is dispersed in a liquid carrier to form a bacterial suspension, and the bacterial suspension is injected into the internal region of the fermentation substrate at a controllable flow rate through an injection tube pre-embedded inside the fermentation substrate or inserted deep into the fermentation substrate. The spatial distribution of the injection points allows the bacterial suspension to form a basically uniform penetration and diffusion within the fermentation substrate.

[0009] As a further aspect of the present invention: the organic waste raw material includes a mixture of livestock and poultry manure and crop straw, the pretreatment includes mixing the livestock and poultry manure and the crop straw at a weight ratio of 1:0.5 to 3, adding a conditioner to adjust the moisture content of the resulting mixture to 50% to 65% and the carbon-nitrogen ratio to 20:1 to 35:1, adding at least one pH adjuster selected from calcium oxide, calcium hydroxide or calcium carbonate to adjust the pH value of the mixture to the range of 6.5 to 8.5, and adding at least one expansion agent selected from rice husk, perlite, sawdust or expanded perlite to make the free space of the mixture not less than 30%.

[0010] As a further aspect of the present invention: during the transition from the first mesophilic fermentation stage to the high-temperature fermentation stage, and from the high-temperature fermentation stage to the second mesophilic fermentation stage, the power of the heating device or cooling device is continuously adjusted to allow the temperature of the fermentation substrate to increase or decrease linearly at a rate not exceeding 5°C / day.

[0011] As a further aspect of the present invention: the microbial strains with cellulose degradation ability in the composting agent are selected from the Trichoderma genus, and the microbial strains with lignin degradation ability are selected from the target strains of white-rot fungi; and the composting agent is domesticated and cultured before inoculation so that the optimal operating temperature range of the cellulase and lignin-degrading enzyme produced by it matches the temperature range of the second mesophilic fermentation stage.

[0012] Furthermore, as a further aspect of the present invention: a segmented temperature-controlled fermentation organic fertilizer, wherein the number of viable cellulose-degrading bacteria in the organic fertilizer is not less than... CFU / g, the number of viable lignin-degrading bacteria is not less than The organic fertilizer contains CFU / g and humic acid content of not less than 15%, and the cellulose-degrading bacteria and the lignin-degrading bacteria are intertwined in the organic fertilizer.

[0013] Compared with existing technologies, the beneficial effects of this invention are as follows: By setting an adaptive segmented temperature control strategy that automatically switches temperature stages based on real-time physicochemical parameters of the fermentation substrate, the shortcomings of traditional timed intermittent switching that ignores the actual decomposition state of the substrate are solved, making the metabolic activity of microorganisms highly matched with the degradation kinetics of the substrate; at the same time, an alternating operation mode of intermittent positive pressure oxygen supply and natural convection ventilation is introduced in the high-temperature stage to construct an alternating aerobic and facultative anaerobic microenvironment inside the pile, effectively inducing the synthesis and expression of lignin-degrading enzyme systems, and significantly improving the decomposition efficiency of stubborn components such as cellulose and lignin; in addition, in the second meso-temperature stage, a liquid deep-layer directional injection method is used to inoculate the composting agent, taking advantage of the window period when the porosity of the pile increases and the temperature is suitable for the survival of functional bacteria, the bacterial suspension is accurately delivered to the internal area of ​​the pile, which significantly improves the survival rate and distribution uniformity of functional bacteria. Attached Figure Description

[0014] Figure 1 This is a main flowchart of a segmented temperature-controlled fermentation method for preparing organic fertilizer in an embodiment of the present invention. Detailed Implementation

[0015] The technical solutions of 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.

[0016] Example 1: This embodiment provides a method for preparing segmented temperature-controlled fermentation organic fertilizer, including the following steps: (1) Pre-treat the organic waste raw materials, adjust the moisture content and carbon-nitrogen ratio to obtain the fermentation substrate: mix pig manure and corn stalks at a weight ratio of 1:1.5, add wheat bran as a conditioner, adjust the moisture content of the mixture to 60% and the carbon-nitrogen ratio to 28:1 to obtain the fermentation substrate.

[0017] (2) Perform the first mesophilic fermentation stage, controlling the temperature of the fermentation substrate within the optimal growth range for thermophilic bacteria: Place the above-mentioned fermentation substrate into a fermenter equipped with a heating device and a ventilation system, controlling the temperature at 38℃ (the optimal growth temperature for thermophilic bacteria), while maintaining a low ventilation rate (0.1 m³ / s). 3 / (min·m 3 Maintain the oxygen content of the material and monitor the concentration of volatile fatty acids (VFA) and pH value of the fermentation substrate daily; simultaneously, prepare a composting inoculum (a 1:1 mixture of *Trichoderma reesei* and *Procambarus jaundice*, acclimatized to an optimal enzyme production temperature of 45-50℃), and inoculate using a liquid deep-layer directional injection method: prepare the inoculum into a bacterial suspension (concentration of...). (CFU / mL) is injected at a flow rate of 1.0 L / min through multi-layer injection tubes pre-embedded inside the reactor body, with an injection volume of 20 L per cubic meter of reactor body.

[0018] (3) Real-time monitoring of physicochemical parameters; automatic switching to the high-temperature stage when the first preset threshold is reached; and the alternating mode of intermittent positive pressure oxygen supply and natural convection ventilation to form an aerobic-facultative anaerobic alternating microenvironment: when the VFA concentration in the fermentation substrate is detected to drop to 40% of the initial concentration (i.e., reaching the first preset threshold), the fermenter is automatically triggered to switch to the high-temperature fermentation stage. The temperature is controlled to rise to 63℃ (the optimal growth temperature for thermophilic bacteria), and the alternating mode of intermittent positive pressure oxygen supply and natural convection ventilation is started: forced ventilation is stopped after 5 minutes, and natural ventilation is started at the exhaust port for 20 minutes, and this cycle is repeated. During the operation of the high-temperature stage, the oxygen concentration in the deep layer of the pile fluctuates periodically between 5-15%. The VFA concentration and pH value are continuously monitored.

[0019] (4) Continuously monitor the physicochemical parameters. When the second preset threshold is reached, switch to the second meso-temperature stage and inoculate the inside of the pile with a composting agent containing cellulose-degrading bacteria and lignin-degrading bacteria by liquid deep directional injection. When the VFA concentration drops to 30% of the peak concentration of the high-temperature stage (i.e., the second preset threshold is reached), automatically trigger the fermenter to switch to the second meso-temperature fermentation stage and control the temperature to gradually drop to 47℃ (the optimal growth temperature for facultative anaerobic fungi). The heating / cooling transition rate is 3℃ / day.

[0020] (5) Continuously monitor the physicochemical parameters until the fermentation termination threshold is reached, and end the segmented temperature-controlled fermentation process: continuously monitor the VFA concentration, and end the fermentation when it drops to a stable low value (less than 10% of the initial concentration). Let the fermentation product age and pile it under natural conditions for 7 days, keeping the moisture content not exceeding 35%, to obtain the finished organic fertilizer.

[0021] Testing revealed that the viable count of cellulose-degrading bacteria in the organic fertilizer prepared in this embodiment was 1.2 × 10⁻⁶. CFU / g, viable count of lignin-degrading bacteria is 8.5× The concentration of CFU / g and the humic acid content is 18.5%. The fermentation cycle is 14 days, which is 44% shorter than that of traditional constant temperature composting (25 days). The organic fertilizer has a 76% control effect on bacterial wilt in potted tomatoes, which is significantly better than the 32% of commercially available ordinary organic fertilizers.

[0022] Sources and acclimatization methods of composting inoculants: The *Trichoderma reesei* (CICC 40357) and *Phanerochaete chrysosporium* (CICC 40299) used were both purchased from the China Industrial Microbial Culture Collection Center (CICC). The optimal growth temperatures of the original strains were 28-30℃ and 37-39℃, respectively, and the optimal enzyme production temperatures were 30℃ and 37℃, respectively. To match the optimal temperature ranges for the cellulase and lignin-degrading enzymes produced by the strains with the temperature range of the first mesophilic fermentation stage, the strains underwent gradient acclimatization culture: using a modified PDA medium containing 0.5% cellobiose and 0.2% guaiacol as the base, the initial culture temperature was set at 30℃ (*Trichoderma reesei*) or 39℃ (*Phanerochaete chrysosporium*), and the culture temperature was increased by 2℃ every 48 hours. At the same time, heat-resistant colonies were screened, and the culture was continuously subcultured for 14 days to finally obtain an acclimatized strain that could stably produce enzymes at 47±2℃. The cellulase activity (CMC) of the domesticated Trichoderma reesei at 47℃ was 85% of that of the original strain at 30℃, and the laccase activity of the domesticated Protozoa jaundice at 47℃ was 78% of that of the original strain at 37℃, meeting the practical requirements.

[0023] The above-mentioned domesticated strains can be preserved for a long time by conventional slant culture (4℃) or glycerol cryopreservation (-80℃). When using them, they can be activated and cultured according to the method described in the examples.

[0024] Example 2: This embodiment repeats the steps of Embodiment 1, but adjusts the following parameters: chicken manure and rice straw are mixed at a weight ratio of 1:2, the moisture content is adjusted to 55%, and the C / N ratio is adjusted to 25:1; the temperature for the first meso-temperature stage is 40℃; the temperature for the high-temperature stage is 65℃; and the temperature for the second meso-temperature stage is 50℃. The composting inoculants used are *Trichoderma viride* and *Pleurotus ostreatus*. Other conditions are the same as in Embodiment 1. The resulting organic fertilizer has a fermentation cycle of 16 days, a humic acid content of 17.2%, and a cellulose-degrading bacteria viable count of 8.6 × 10⁻⁶. CFU / g, viable count of lignin-degrading bacteria 6.2× CFU / g.

[0025] Example 3: This embodiment repeats the steps of Embodiment 1, but changes the stage switching criterion from VFA concentration to pH value: the first preset threshold is when the pH value rises to 8.3; the second preset threshold is when the pH value falls back and stabilizes at 7.8. Other conditions are the same as in Embodiment 1. The various indicators of the obtained organic fertilizer are basically the same as those in Embodiment 1, and the fermentation cycle is 15 days, verifying the feasibility of using pH value as the switching criterion.

[0026] The working principle of this invention is as follows: Step 1: Pre-treat the organic waste raw material, adjust its moisture content, carbon-nitrogen ratio, pH value and porosity to a range suitable for microbial growth, and obtain a fermentation substrate; Step 2: Place the fermentation substrate into the fermentation device and execute the first mesophilic fermentation stage. Control the temperature of the fermentation substrate to be maintained within the optimal growth temperature range of the thermophilic bacteria. In the first mesophilic fermentation stage, inoculate the fermentation substrate with a composting agent by liquid deep directional injection. The composting agent contains at least one microbial strain with cellulose degradation ability and at least one microbial strain with lignin degradation ability. Step 3: During the first mesophilic fermentation stage, at least one physicochemical parameter of the fermentation substrate is continuously or intermittently monitored in real time. When the physicochemical parameter reaches a first preset threshold, the fermentation device is automatically triggered to switch to the high-temperature fermentation stage. The temperature of the fermentation substrate is controlled to be maintained within the optimal growth temperature range of thermophilic bacteria. In the high-temperature fermentation stage, a strategy of alternating intermittent positive pressure oxygen supply and natural convection ventilation is adopted to form an alternating aerobic and facultative anaerobic microenvironment inside the fermentation substrate. Step 4: During the high-temperature fermentation stage, the physicochemical parameters are continuously monitored. When the physicochemical parameters reach the second preset threshold, the fermentation device is automatically switched to the second mesophilic fermentation stage. The temperature of the fermentation substrate is controlled to be maintained within the optimal growth temperature range of facultative anaerobic fungi. In the second mesophilic fermentation stage, a composting agent is inoculated into the fermentation substrate by liquid deep-layer directional injection. The composting agent contains at least one microbial strain with cellulose degradation ability and at least one microbial strain with lignin degradation ability. Step 5: Continuously monitor the physicochemical parameters until they reach the fermentation termination threshold, and end the segmented temperature-controlled fermentation process.

[0027] In summary, by setting an adaptive segmented temperature control strategy that automatically switches temperature stages based on real-time physicochemical parameters of the fermentation substrate, the shortcomings of traditional timed intermittent switching that ignores the actual decomposition state of the substrate are solved, and the metabolic activity of microorganisms is highly matched with the degradation kinetics of the substrate. At the same time, the introduction of an alternating operation mode of intermittent positive pressure oxygen supply and natural convection ventilation in the high-temperature stage creates an alternating aerobic and facultative anaerobic microenvironment inside the pile, which effectively induces the synthesis and expression of lignin-degrading enzymes and significantly improves the decomposition efficiency of stubborn components such as cellulose and lignin. In addition, in the second mesophilic stage, the fermentation agent is inoculated by liquid deep-layer directional injection. Taking advantage of the window period when the porosity of the pile increases and the temperature is suitable for the survival of functional bacteria, the bacterial suspension is accurately delivered to the internal area of ​​the pile, which significantly improves the survival rate and distribution uniformity of functional bacteria.

[0028] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A preparation method of a segmented temperature-controlled fermented organic fertilizer, characterized by, include: Step 1: Pre-treat the organic waste raw materials by adjusting their moisture content, carbon-nitrogen ratio, pH value and porosity to a range suitable for microbial growth to obtain a fermentation substrate; Step 2: Place the fermentation substrate into the fermentation device and execute the first mesophilic fermentation stage. Control the temperature of the fermentation substrate to be maintained within the optimal growth temperature range of the thermophilic bacteria. In the first mesophilic fermentation stage, inoculate the fermentation substrate with a composting agent by liquid deep directional injection. The composting agent contains at least one microbial strain with cellulose degradation ability and at least one microbial strain with lignin degradation ability. Step 3: During the first mesophilic fermentation stage, at least one physicochemical parameter of the fermentation substrate is continuously or intermittently monitored in real time. When the physicochemical parameter reaches a first preset threshold, the fermentation device is automatically switched to the high-temperature fermentation stage. The temperature of the fermentation substrate is controlled to be maintained within the optimal growth temperature range of thermophilic bacteria. In the high-temperature fermentation stage, a strategy of alternating intermittent positive pressure oxygen supply and natural convection ventilation is adopted to form an aerobic-facultative anaerobic alternating microenvironment inside the fermentation substrate. Step 4: During the high-temperature fermentation stage, the physicochemical parameters are continuously monitored. When the physicochemical parameters reach the second preset threshold, the fermentation device is automatically switched to the second mesophilic fermentation stage to control the temperature of the fermentation substrate to be maintained within the optimal growth temperature range of facultative anaerobic fungi. Step 5: Continuously monitor the physicochemical parameters until they reach the fermentation termination threshold, and end the segmented temperature-controlled fermentation process.

2. The method for preparing organic fertilizer by segmented temperature-controlled fermentation according to claim 1, characterized in that, The physicochemical parameters are selected from at least one of volatile fatty acid concentration or pH value; the first preset threshold is when the volatile fatty acid concentration drops to 30% to 50% of its initial concentration, or when the pH value rises to 8.0 to 8.5; the second preset threshold is when the volatile fatty acid concentration drops again to 20% to 40% of the peak concentration reached in the high-temperature fermentation stage, or when the pH value falls back and stabilizes in the range of 7.5 to 8.

0.

3. The method for preparing organic fertilizer by segmented temperature-controlled fermentation according to claim 1, characterized in that, The strategy of alternating intermittent positive pressure oxygen supply and natural convection ventilation specifically includes: After supplying heated or unheated air to the fermentation substrate with a forced ventilation device for 3 to 8 minutes, the forced ventilation is stopped and the exhaust port of the fermentation device is opened to allow natural convection for ventilation for 10 to 30 minutes. The alternating cycle of forced ventilation and natural convection ventilation is repeated so that the oxygen concentration in the deep area of ​​the fermentation substrate fluctuates periodically within the range of 5% to 15%.

4. The method for preparing organic fertilizer by segmented temperature-controlled fermentation according to claim 1, characterized in that, The method of deep directional injection of liquid is as follows: The fermentation agent is dispersed in a liquid carrier to form a bacterial suspension. The bacterial suspension is injected into the internal area of ​​the fermentation substrate through an injection tube that is pre-embedded inside the fermentation substrate or can be inserted deep into the fermentation substrate at a controllable flow rate. The spatial distribution of the injection points allows the bacterial suspension to form a basically uniform penetration and diffusion within the fermentation substrate.

5. The method for preparing organic fertilizer by segmented temperature-controlled fermentation according to claim 1, characterized in that, The organic waste raw material includes a mixture of livestock and poultry manure and crop straw. The pretreatment includes mixing the livestock and poultry manure and the crop straw at a weight ratio of 1:0.5 to 3, adding a conditioner to adjust the moisture content of the resulting mixture to 50% to 65% and the carbon-nitrogen ratio to 20:1 to 35:1, adding at least one pH adjuster selected from calcium oxide, calcium hydroxide or calcium carbonate to adjust the pH value of the mixture to the range of 6.5 to 8.5, and adding at least one expansion agent selected from rice husk, perlite, sawdust or expanded perlite to make the free space of the mixture not less than 30%.

6. The method for preparing organic fertilizer by segmented temperature-controlled fermentation according to claim 1, characterized in that, During the transition from the first mesophilic fermentation stage to the high-temperature fermentation stage, and from the high-temperature fermentation stage to the second mesophilic fermentation stage, the temperature of the fermentation substrate is linearly increased or decreased at a rate not exceeding 5°C / day by continuously adjusting the power of the heating or cooling device.

7. The method for preparing organic fertilizer by segmented temperature-controlled fermentation according to claim 1, characterized in that, The microbial strains with cellulose degradation ability in the composting agent are selected from the Trichoderma genus, and the microbial strains with lignin degradation ability are selected from the target strains of white-rot fungi; and the composting agent is acclimatized and cultured before inoculation so that the optimal operating temperature range of the cellulase and lignin-degrading enzyme produced by it matches the temperature range of the second mesophilic fermentation stage.

8. A segmented temperature-controlled fermentation organic fertilizer, characterized in that, The organic fertilizer is prepared by any one of claims 1 to 7, wherein the number of viable cellulose-degrading bacteria in the organic fertilizer is not less than [amount missing]. CFU / g, the number of viable lignin-degrading bacteria is not less than The organic fertilizer contains CFU / g and humic acid content of not less than 15%, and the cellulose-degrading bacteria and the lignin-degrading bacteria are intertwined in the organic fertilizer.

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