Biological waste fermentation and biogas synergistic heat production and fertilizer supply method

Abstract

The invention discloses a biological waste fermentation and biogas synergistic heat production and fertilizer supply method, and relates to the technical field of biological resource treatment, and the method comprises the following specific steps: biological waste classification pretreatment, material proportioning mixing and crushing, anaerobic fermentation synergistic biogas recovery, fermentation material decomposition regulation and control, and flora inoculation and after-ripening. The utilization rate of the raw materials is effectively improved through classification pretreatment of the raw materials, such as impurity cleaning of weeds, normal-temperature soaking of cellulase and stirring and scattering of excrement, and in the material matching, mixing and crushing stages, the uniformity and high efficiency of the fermentation raw materials are ensured by controlling the mass ratio of the weeds to the excrement and the crushing particle size, so that the fermentation efficiency is improved. In the anaerobic fermentation process, biogas is recycled to serve as recycling energy, heat released by fermentation is collected through the heat exchange component to be used for heat supply, multi-stage utilization of energy is achieved, meanwhile, clean and safe utilization of the biogas is guaranteed through gas-liquid separation and desulfurization treatment, and greenhouse gas emission is reduced.

Description

Technical Field

[0001] This invention relates to the field of biological resource treatment technology, specifically a method for the synergistic heat production and fertilizer supply from the fermentation of biological waste and biogas. Background Technology

[0002] With the growth of the global population and the expansion of agricultural activities, the amount of agricultural waste generated is increasing day by day. How to efficiently and environmentally dispose of this waste has become an urgent problem to be solved. Agricultural waste, such as weeds and livestock manure, if not properly disposed of, not only occupies land resources, but may also cause environmental pollution, such as eutrophication of water bodies and soil pollution. At the same time, the demand for efficient and environmentally friendly fertilizers in agriculture is also constantly increasing in order to improve crop yield and quality. Against this background, the technology of resource utilization of biological waste has emerged.

[0003] However, despite some progress in the technology for the resource utilization of biological waste, traditional methods still have many shortcomings in terms of processing efficiency, product quality, and environmental impact. Some traditional technologies have relatively simple pretreatment of raw materials, resulting in low utilization rates of raw materials during fermentation, which affects the yield and quality of organic fertilizer. In the material proportioning and crushing stages, there is a lack of effective control, resulting in poor uniformity of fermentation raw materials and unstable fermentation effects. In addition, traditional technologies are somewhat inadequate in the recovery of biogas produced during fermentation and often neglect the collection and reuse of heat released during fermentation, resulting in energy waste. At the same time, the gas-liquid separation and desulfurization treatment are not perfect, resulting in high impurity content in biogas, making it difficult to use directly as a clean energy source and limiting the widespread application of biogas. In terms of organic fertilizer preparation, traditional technologies rely heavily on experience to determine the degree of decomposition, lacking scientific basis, which leads to inconsistent maturity of organic fertilizer and affects the application effect on crops. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for the synergistic heat production and fertilization of biological waste fermentation and biogas. This invention effectively improves the utilization rate of raw materials through classified pretreatment, such as cleaning impurities from weeds and soaking them in cellulase at room temperature, as well as stirring and breaking up manure. In the material proportioning, mixing and crushing stage, the uniformity and efficiency of fermentation raw materials are ensured by controlling the mass ratio of weeds to manure and the crushing particle size. During the anaerobic fermentation process, not only is biogas recovered as a reusable energy source, but the heat released during fermentation is also collected through heat exchange components for heating, realizing multi-level energy utilization. At the same time, gas-liquid separation and desulfurization treatment ensure the clean and safe utilization of biogas, reduce greenhouse gas emissions, and solve the problem of agricultural waste treatment.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for the synergistic heat production and fertilizer supply from biological waste fermentation and biogas production, the specific steps of which are as follows: Biological waste sorting and pretreatment: Weeds with high fiber content and highly adhesive manure are selected as raw materials and pretreatment is carried out. After cleaning impurities from the weeds, they are soaked in cellulase solution at room temperature. The manure is broken up by stirring. Material proportioning, mixing and crushing: The pre-treated weeds and manure are put into the mixing equipment according to the preset mass ratio for mixing, and the mixed material is sent to the crushing equipment for crushing. Anaerobic fermentation with biogas recovery: The crushed material is transported to the anaerobic fermentation unit, and the environmental parameters inside the anaerobic fermentation unit are controlled for fermentation. The biogas produced by fermentation is gas-liquid separated, desulfurized and then collected and stored in the biogas storage tank. At the same time, the heat released by fermentation is collected through heat exchange components and then transported to the heat storage unit for storage. Fermentation material composting control: During the fermentation process, the temperature of the material is collected in real time by temperature monitoring components. Combined with the appearance and pH value of the material, it is determined whether the material is composted. After the material is determined to be composted, it is transported to a temporary storage silo. Microbial inoculation and post-fermentation: The functional mixed microbial agent is introduced into the decomposed material in the temporary storage chamber, and the stirring component is started to mix the functional mixed microbial agent with the decomposed material; the material after inoculation is transferred to the constant temperature post-fermentation component, and the temperature inside the constant temperature post-fermentation component is controlled for post-fermentation treatment to complete the preparation of organic fertilizer.

[0006] Furthermore, in the pretreatment of biological waste sorting, the impurities of weeds are removed by screening to remove gravel, plastic fragments and metal debris; the cellulase solution uses neutral cellulase with a mass concentration of 0.4-0.6%, the ambient temperature for soaking is 15-25℃, and the soaking time is 3.5-4.5 hours; the manure is stirred by a mixer with a stirring speed of 300-500 r / min and a stirring time of 15-30 minutes, and the treated manure has no lumps with a diameter greater than 4-6 mm.

[0007] Furthermore, in the pretreatment of biological waste sorting, the weeds are intermittently stirred during the room temperature soaking process. The frequency of intermittent stirring is once every 0.8-1.2 hours, and the duration of each stirring is 4.8-8.2 minutes.

[0008] Furthermore, in the material proportioning, mixing, and crushing process, the preset mass ratio of pretreated weeds to manure is 2.8:2-3.2:2; the mixing equipment is a twin-shaft paddle mixer with a mixing speed of 190-310 r / min and a mixing time of 15-30 minutes; the crushing equipment is a double-roll crusher with a roller speed of 10-20 r / min, and the particle size of the crushed material is 5-10 mm by adjusting the roller spacing.

[0009] Furthermore, in the anaerobic fermentation and biogas recovery process, the internal temperature of the anaerobic fermentation component is controlled at 35-40℃, and the fermentation duration is 15-20 days; gas-liquid separation is performed by a gas-liquid separator, and the biogas moisture content after gas-liquid separation is less than 9-11%; desulfurization is performed by a desulfurization tower, and the H2S content in the biogas after desulfurization is less than 180-220ppm.

[0010] Furthermore, in the fermentation material maturation control, the temperature monitoring component is a platinum resistance temperature sensor. One to two platinum resistance temperature sensors are arranged in the surface, middle, and bottom layers of the anaerobic fermentation component. The temperature acquisition frequency is once every 0.8 to 1.2 hours. The temperature conditions for determining maturation are that the material temperature drops to 29-31℃ and is maintained at 28-32℃ for 2.8-3.2 consecutive days, the material appearance conditions are that the material is dark brown and loose in texture, and the pH value condition is 6.8-8.2.

[0011] Furthermore, in the inoculation and post-ripening of the microbial community, the functional mixed microbial agent consists of phosphate-solubilizing bacteria and nitrogen-fixing bacteria, wherein the phosphate-solubilizing bacteria is Bacillus cereus and the nitrogen-fixing bacteria is Azotobacter brownii, and the mixing ratio of phosphate-solubilizing bacteria to nitrogen-fixing bacteria is 0.9:1-1.1:1, with a viable count of ≥0.8×10⁻⁶ for both. 8 -1.2×10 8 The inoculation amount of the functional mixed microbial agent is 0.28-0.32% of the total mass of the composted material. Before inoculation, the functional mixed microbial agent is diluted 10-20 times with sterile water and then sprayed evenly through the spray component. The stirring speed of the stirring component is 145-205 r / min and the stirring time is 4.8-10.2 minutes.

[0012] Furthermore, in the inoculation and post-ripening process, the constant-temperature post-ripening component is a fermentation chamber equipped with a heating jacket; during the post-ripening process, the ambient temperature inside the constant-temperature post-ripening component is controlled at 30-35℃, and the post-ripening duration is 6.5-7.5 days; during the post-ripening period, regular ventilation is performed, with a frequency of once every 1.8-2.2 days, and each ventilation lasts for 28-62 minutes.

[0013] Compared with existing technologies, this method of co-producing heat and fertilizer from biological waste fermentation and biogas has the following beneficial effects: I. This invention effectively improves the utilization rate of raw materials through classification and pretreatment, such as cleaning impurities from weeds and soaking them in cellulase at room temperature, as well as stirring and breaking up manure. In the material proportioning, mixing, and crushing stages, the uniformity and efficiency of fermentation raw materials are ensured by controlling the mass ratio of weeds to manure and the crushing particle size. During the anaerobic fermentation process, not only is biogas recovered as a reusable energy source, but the heat released during fermentation is also collected through heat exchange components for heating, realizing multi-level energy utilization. At the same time, gas-liquid separation and desulfurization treatment ensure the clean and safe utilization of biogas, reduce greenhouse gas emissions, and solve the problem of agricultural waste treatment.

[0014] Second, this invention uses a temperature monitoring component to collect material temperature in real time and combines it with the material's appearance and pH value to comprehensively determine the degree of composting, ensuring the full maturity and stability of the organic fertilizer. In the microbial inoculation stage, a functional mixed microbial agent composed of phosphate-solubilizing bacteria and nitrogen-fixing bacteria is selected, diluted with sterile water, and evenly sprayed onto the composted material, thereby increasing the content of beneficial microorganisms in the organic fertilizer. The post-ripening stage is carried out under constant temperature conditions, and regular ventilation promotes the activity of microorganisms and the transformation of substances, improving the quality of the organic fertilizer. The organic fertilizer prepared by this method is rich in nutrients and beneficial microorganisms, which can improve crop yield and quality.

[0015] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0017] Figure 1 This is a flowchart of a method for co-producing heat and fertilizer from biological waste through fermentation and biogas production. Detailed Implementation

[0018] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0019] Example 1: In the scenario of large-scale co-treatment of farmland waste and livestock manure, field weeds with high fiber content and highly adhesive manure from livestock farms are selected as raw materials. The weeds are screened to remove impurities such as gravel, plastic fragments, and metal debris. Then, a neutral cellulase solution with a mass concentration of 0.5% is prepared. The cleaned weeds are placed in the neutral cellulase solution and soaked at room temperature of 20°C for 4 hours. During the soaking process, the weeds are intermittently stirred once every 1 hour for 6.5 minutes each time. The manure is stirred and broken up using a mixer with a stirring speed of 400 r / min for 20 minutes. After treatment, it is ensured that there are no lumps with a diameter greater than 5 mm in the manure.

[0020] The pretreated weeds and manure were fed into a twin-shaft paddle mixer at a preset mass ratio of 3.0:2 ​​and mixed at a mixing speed of 250 r / min for 20 minutes to ensure that the weeds and manure were fully blended. After mixing, the material was fed into a double-roll crusher for crushing. The roller speed was set to 15 r / min and the particle size of the crushed material was controlled to be about 7 mm by adjusting the roller gap.

[0021] The crushed mixture is transported to an anaerobic fermentation unit, specifically a CSTR reactor, with the ambient temperature controlled at 38°C for 18 days of anaerobic fermentation. The biogas produced during fermentation is first processed through a gravity-type gas-liquid separator, reducing the water content of the biogas to 10%. The separated biogas is then fed into a desulfurization tower filled with iron oxide desulfurizing agent for desulfurization, ensuring that the H2S content in the desulfurized biogas is below 200 ppm. Finally, the processed biogas is collected and stored in a biogas storage tank. Simultaneously, the heat released during fermentation is collected by heat exchange components in the CSTR reactor and transferred to a heat storage unit for later use. Figure 1 As shown, it provides a heat source for subsequent material handling or related needs.

[0022] During the anaerobic fermentation process, a platinum resistance temperature sensor was used to collect the material temperature in real time. One sensor was placed in each of the surface, middle, and bottom layers of the CSTR reactor, and the temperature was collected every hour. The maturity was determined by combining the material appearance and pH value. When the material temperature dropped to 30℃ and remained in the 28-32℃ range for three consecutive days, the material was observed to be dark brown and loose in texture. At the same time, the pH value of the material was measured to be 7.5, which met the maturity determination criteria. The matured material was then transferred to a temporary storage bin through a conveying device to prepare for the subsequent preparation of organic fertilizer for farmland.

[0023] Prepare a functional mixed bacterial agent, composed of Bacillus cereus and Azotobacter brownins in a 1:1 ratio, with a viable count of 1.0 × 10⁻⁶ for both Bacillus cereus and Azotobacter brownins. 8 CFU / g; The functional mixed microbial agent was diluted 15 times with sterile water at an inoculation rate of 0.3% of the total mass of the composted material, and then evenly sprayed onto the composted material in the temporary storage chamber using a spray unit. The mixing unit was then used to thoroughly mix the functional mixed microbial agent with the composted material, setting the stirring speed to 175 r / min and the stirring time to 7.5 minutes. The inoculated material was then transferred to a fermentation chamber equipped with a heating jacket, and the ambient temperature inside the chamber was controlled at 32℃ for a 7-day post-fermentation treatment. During the post-fermentation period, regular ventilation was performed every 2 days for 45 minutes each time, ultimately producing an organic fertilizer suitable for farmland fertilization.

[0024] In summary, in the scenario of large-scale fermentation of farmland biological waste and co-generation of biogas for heat and fertilizer supply, farmland organic fertilizer is finally produced by treating field weeds and livestock manure, mixing and crushing them, anaerobic fermenting them in a CSTR reactor and recovering biogas and heat, and then controlling the composting of fermented materials, inoculating microorganisms and post-ripening.

[0025] Example 2: In the scenario of forest biological waste fermentation and biogas co-generation for heat and fertilizer supply, forest weeds with high fiber content and livestock manure were selected as raw materials. The weeds were screened to remove impurities such as gravel, plastic fragments, and metal debris. A neutral cellulase solution with a mass concentration of 0.6% was prepared. The cleaned weeds were placed in the neutral cellulase solution and soaked at room temperature of 25°C for 4.5 hours. During the soaking process, the mixture was stirred intermittently, once every 1.2 hours, for 8.2 minutes each time. The manure was stirred and broken up using a mixer with a stirring speed of 500 r / min and a stirring time of 30 minutes. After treatment, it was ensured that there were no lumps with a diameter greater than 6 mm in the manure.

[0026] The pretreated weeds and manure were fed into a twin-shaft paddle mixer at a mass ratio of 3.2:2. The mixing speed was set to 310 r / min and the mixing time was 30 minutes to achieve uniform fusion of weeds and manure. The mixed material was then fed into a double-roll crusher for crushing. The roller speed was set to 20 r / min. By adjusting the roller spacing, the particle size of the crushed material was controlled to be around 5 mm, laying the foundation for subsequent efficient fermentation and organic fertilizer preparation.

[0027] The crushed material is transported to an anaerobic fermentation unit, which is a UASB reactor. The ambient temperature inside the UASB reactor is controlled at 40°C, and fermentation continues for 20 days. The biogas produced by fermentation is first passed through a packed gas-liquid separator for gas-liquid separation. After treatment, the water content of the biogas is reduced to 9%. The biogas is then sent to a desulfurization tower filled with activated carbon desulfurizing agent for desulfurization treatment to ensure that the H2S content in the desulfurized biogas is less than 180ppm. The qualified biogas is collected and stored in a biogas storage tank for heat supply to forest-related facilities. At the same time, the heat released by fermentation is collected through heat exchange components and transported to a heat storage component for storage, realizing the recovery of biogas and heat.

[0028] During fermentation, platinum resistance temperature sensors are used to collect the material temperature in real time. Two platinum resistance temperature sensors are placed in the surface, middle and bottom layers of the UASB reactor, and the temperature is collected once every 0.8 hours. The maturity status is determined by the appearance of the material and the pH value. When the material temperature drops to 31℃ and is maintained in the range of 28-32℃ for 3.2 consecutive days, the material is dark brown and loose in texture, and the pH value is 8.0, the material is determined to be mature and is then transferred to a temporary storage bin by a conveying device.

[0029] A functional mixed bacterial agent was prepared by mixing Bacillus cereus and Azotobacter brownins in a ratio of 1.1:1, with a viable count of 1.2 × 10⁻⁶ for both Bacillus cereus and Azotobacter brownins. 8 CFU / g; The functional mixed microbial agent was diluted 20 times with sterile water at an inoculation rate of 0.32% of the total mass of the composted material, and then evenly sprayed onto the composted material in the temporary storage chamber using a spray unit. The mixing unit was then used to ensure thorough mixing of the functional mixed microbial agent with the composted material, with a stirring speed of 205 r / min and a stirring time of 10.2 minutes. The inoculated material was then transferred to a fermentation chamber equipped with a heating jacket, and the temperature inside the chamber was controlled at 35℃ for 7.5 days of post-fermentation. During the post-fermentation period, ventilation was carried out once every 1.8 days for 62 minutes each time, ultimately producing an organic fertilizer suitable for use in forest crops.

[0030] In summary, in the scenario of forest land biological waste fermentation and biogas co-generation for heat and fertilizer supply, forest land weeds and livestock farm manure are treated, mixed and crushed, anaerobic fermented in a UASB reactor to recover biogas and heat, and then matured and inoculated with microorganisms to produce forest land organic fertilizer.

[0031] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for co-producing heat and fertilizer from biological waste through fermentation and biogas production, characterized in that, The specific steps of this method are as follows: Biological waste sorting and pretreatment: Weeds with high fiber content and highly adhesive manure are selected as raw materials and pretreatment is carried out. After cleaning impurities from the weeds, they are soaked in cellulase solution at room temperature. The manure is broken up by stirring. Material proportioning, mixing and crushing: The pre-treated weeds and manure are put into the mixing equipment according to the preset mass ratio for mixing, and the mixed material is sent to the crushing equipment for crushing. Anaerobic fermentation with biogas recovery: The crushed material is transported to the anaerobic fermentation unit, and the environmental parameters inside the anaerobic fermentation unit are controlled for fermentation. The biogas produced by fermentation is gas-liquid separated, desulfurized and then collected and stored in the biogas storage tank. At the same time, the heat released by fermentation is collected through heat exchange components and then transported to the heat storage unit for storage. Fermentation material composting control: During the fermentation process, the temperature of the material is collected in real time by temperature monitoring components. Combined with the appearance and pH value of the material, it is determined whether the material is composted. After the material is determined to be composted, it is transported to a temporary storage silo. Microbial inoculation and post-fermentation: The functional mixed microbial agent is introduced into the decomposed material in the temporary storage chamber, and the stirring component is started to mix the functional mixed microbial agent with the decomposed material; the material after inoculation is transferred to the constant temperature post-fermentation component, and the temperature inside the constant temperature post-fermentation component is controlled for post-fermentation treatment to complete the preparation of organic fertilizer.

2. The method for co-producing heat and fertilizer from biological waste fermentation and biogas as described in claim 1, characterized in that, In the pretreatment of biological waste sorting, the impurities of weeds are removed by screening to remove gravel, plastic fragments and metal debris; the cellulase solution uses neutral cellulase with a mass concentration of 0.4-0.6%, the ambient temperature for soaking is 15-25℃, and the soaking time is 3.5-4.5 hours; the manure is stirred by a mixer at a speed of 300-500 r / min for 15-30 minutes, and the treated manure has no lumps with a diameter greater than 4-6 mm.

3. The method for co-producing heat and fertilizer from biological waste fermentation and biogas as described in claim 2, characterized in that, In the pretreatment of biological waste sorting, the weeds are intermittently stirred during the room temperature soaking process. The frequency of intermittent stirring is once every 0.8-1.2 hours, and the duration of each stirring is 4.8-8.2 minutes.

4. The method for co-producing heat and fertilizer from biological waste fermentation and biogas as described in claim 1, characterized in that, In the material proportioning, mixing, and crushing process, the preset mass ratio of pretreated weeds to manure is 2.8:2-3.2:2; the mixing equipment is a twin-shaft paddle mixer with a mixing speed of 190-310 r / min and a mixing time of 15-30 minutes; the crushing equipment is a double-roll crusher with a roller speed of 10-20 r / min, and the particle size of the crushed material is 5-10 mm by adjusting the roller spacing.

5. The method for co-producing heat and fertilizer from biological waste fermentation and biogas as described in claim 1, characterized in that, In the anaerobic fermentation and biogas recovery process, the internal temperature of the anaerobic fermentation component is controlled at 35-40℃, and the fermentation duration is 15-20 days. Gas-liquid separation is performed by a gas-liquid separator, and the biogas moisture content after gas-liquid separation is less than 9-11%. Desulfurization is performed by a desulfurization tower, and the H2S content in the biogas after desulfurization is less than 180-220ppm.

6. The method for co-producing heat and fertilizer from biological waste fermentation and biogas as described in claim 1, characterized in that, In the process of controlling the fermentation material's maturation, the temperature monitoring component is a platinum resistance temperature sensor. One to two platinum resistance temperature sensors are arranged in each of the surface, middle, and bottom layers of the anaerobic fermentation component. The temperature acquisition frequency is once every 0.8 to 1.2 hours. The temperature conditions for determining maturity are that the material temperature drops to 29-31℃ and is maintained at 28-32℃ for 2.8-3.2 consecutive days, the material appearance conditions are that the material is dark brown and loose in texture, and the pH value conditions are 6.8-8.

2.

7. The method for co-producing heat and fertilizer from biological waste fermentation and biogas as described in claim 1, characterized in that, In the inoculation and post-ripening of the microbial community, the functional mixed inoculum consists of phosphate-solubilizing bacteria and nitrogen-fixing bacteria. The phosphate-solubilizing bacteria are *Bacillus cereus*, and the nitrogen-fixing bacteria are *Azotobacter brownifolia*. The mixing ratio of phosphate-solubilizing bacteria to nitrogen-fixing bacteria is 0.9:1-1.1:1, and the viable count of both is ≥0.8 × 10⁻⁶. 8 -1.2×10 8 The inoculation amount of the functional mixed microbial agent is 0.28-0.32% of the total mass of the composted material. Before inoculation, the functional mixed microbial agent is diluted 10-20 times with sterile water and then sprayed evenly through the spray component. The stirring speed of the stirring component is 145-205 r / min and the stirring time is 4.8-10.2 minutes.

8. The method for co-producing heat and fertilizer from biological waste fermentation and biogas as described in claim 1, characterized in that, In the inoculation and post-ripening process, the constant-temperature post-ripening component is a fermentation chamber equipped with a heating jacket; during the post-ripening process, the ambient temperature inside the constant-temperature post-ripening component is controlled at 30-35℃, and the post-ripening duration is 6.5-7.5 days; during the post-ripening period, regular ventilation is carried out, with a frequency of once every 1.8-2.2 days, and each ventilation lasts for 28-62 minutes.

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