Method for realizing emission reduction synergy of production of padding and greenhouse gas and active nitrogen gas through rapid and safe fermentation of cow dung residues under cold condition

Abstract

The invention belongs to the technical field of livestock and poultry manure management and utilization, and provides a method for realizing emission reduction synergy of production of padding, greenhouse gas and active nitrogen gas through rapid and safe fermentation of cow dung residues under a cold condition, and a heating plate is arranged at the bottom of a pile body to realize heating of cold air output from an aeration pipe at the bottom; and in combination with the ascending flow of the air flow in the pile body, the whole large pile body at the upper part can be effectively heated, and the high-temperature period lasts until the fermentation is finished, so that a good fermentation effect is achieved. Start-stop feedback control of the heating plate is realized by monitoring the temperature of the pile body, so that the energy consumption is effectively reduced, and the cost is greatly reduced. The method has the synergistic effects of promoting efficient and safe fermentation of excrement to produce padding and reducing emission of harmful gases in the environment under the cold condition in winter, is simple to operate, realizes efficient value-added utilization of wastes, and has important value and significance for solving the practical problems of excrement treatment and resource utilization in dairy farms.

Description

Technical Field

[0001] This invention belongs to the field of livestock and poultry manure management and utilization technology. Specifically, it relates to a method for achieving rapid and safe fermentation of cow manure residue to produce bedding material and synergistic reduction of greenhouse gas and reactive nitrogen gas emissions under cold conditions. Background Technology

[0002] With the rapid development of my country's livestock and poultry farming industry, the amount of organic waste such as livestock and poultry manure has increased dramatically. Livestock and poultry manure that has not been treated in a timely, harmless, and resource-efficient manner has become one of the main sources of agricultural non-point source pollution. In recent years, the number of dairy cows in China has reached approximately 11.608 million head, and the large-scale generation of dairy cow manure poses a significant threat to the ecological environment. Dairy farming requires a large amount of bedding material, which is used to spread on the cows' bedding for rest. The increasing cost and decreasing supply of common bedding materials such as rice husks and sawdust have prompted farming enterprises to continuously seek new alternative bedding sources. In recent years, the technology of producing bedding through fermentation of dairy cow manure has been widely used in dairy farms, significantly reducing the economic cost of purchasing bedding materials. Among these methods, the aerobic fermentation of solid manure residue after solid-liquid separation as cow bedding material utilizes aerobic high-temperature fermentation to effectively kill pathogens and is considered to produce highly safe bedding, becoming one of the mainstream production methods for cow bedding material. Due to their advantages such as low cost, ease of operation, and large processing capacity, trough or windrow fermentation is the most common aerobic fermentation process used in large-scale farms. According to current bedding fermentation standards, the high-temperature period (above 55℃) is generally required to be controlled for 5-7 days during fermentation to achieve better killing of key pathogenic bacteria (Staphylococcus aureus, Escherichia coli, molds, etc.). However, farms currently face the problem that cow manure is a cold fertilizer with low calorific value, poor aeration, and low fermentation temperature. Especially in northern regions where winter temperatures are low, aerobic fermentation is difficult to carry out. At the same time, in southern regions, the natural fermentation cycle is generally longer due to low winter temperatures, limiting the timely and sufficient supply of bedding material. This has become a pressing problem that dairy farms urgently need to solve.

[0003] The fermentation process of manure bedding is a high-temperature aerobic fermentation process, which produces large amounts of greenhouse gases and reactive nitrogen gases, including methane (CH4), ammonia (NH3), nitrous oxide (N2O), and nitric oxide (NO). Methane and nitrous oxide are the two most important greenhouse gases in agriculture, while ammonia, nitric oxide, and nitrous oxide are all reactive nitrogen gases. Among these gases, ammonia is the main odor odor, not only causing foul smells in livestock farms and affecting animal growth, but also contributing to atmospheric aerosols and PM2.5. 2.5Methane and nitrous oxide are significant sources of nitrogen oxides; their greenhouse effects are 28 times and 265 times that of CO2, respectively. The fermentation process of manure often involves a microenvironment with both aerobic and anaerobic components, promoting nitrification and denitrification reactions, making it a crucial source of N2O emissions. Simultaneously, the anaerobic environment still produces large amounts of methane. Nitric oxide is a major air pollutant, often produced in large quantities during nitrification and denitrification reactions. After emission, it undergoes a series of transformations in the atmosphere, causing acid rain, photochemical smog, ozone layer depletion, increased particulate matter formation, and harm to human health. Therefore, the reduction and control of greenhouse gases and reactive nitrogen gases during manure fermentation urgently need to be addressed.

[0004] In cold winter conditions, the fermentation of cow manure bedding is difficult or takes a significantly longer time, directly leading to a shortage of manure bedding supply in dairy farms during winter. Currently, farms lack suitable technologies to solve this problem. Often, in winter, they need to purchase large quantities of rice husks for bedding or use drum-type electric heating systems for cow manure bedding production. However, these methods involve significant investment in equipment, energy, and resources, and also result in large accumulations of cow manure on farms during winter, posing a challenge to resource utilization. Therefore, it is necessary to further explore measures to achieve rapid heating and fermentation in winter using mainstream bedding production processes such as trough fermentation and windrow fermentation, while simultaneously controlling greenhouse gas and reactive nitrogen emissions during the fermentation process. Summary of the Invention

[0005] The purpose of this invention is to provide a method for the rapid and safe fermentation of cow dung residue to produce bedding material and the synergistic reduction of greenhouse gas and reactive nitrogen emissions under cold conditions.

[0006] To achieve the objective of this invention, the present invention provides a method for the rapid and safe fermentation of cow dung residue to produce bedding material and the synergistic reduction of greenhouse gas and reactive nitrogen emissions under cold conditions, comprising the following steps: S1. Install ventilation pipes at the bottom of the windrow or trough fermentation zone, and install electric heating plates at the bottom of the fermentation zone; S2. The cow dung residue with an initial moisture content of 60-70% and a carbon-nitrogen ratio of 20-30 is piled up in the fermentation zone to form a pile. S3. Cover the surface of the stack with a molecular film and seal and fix the molecular film. S4. Perform intermittent ventilation on the pile body; S5. Monitor the internal temperature of the pile in real time, and control the start and stop of the electric heating plate through temperature feedback to ensure successful fermentation of the pile and extend the high-temperature period of the pile.

[0007] Furthermore, in step S1, the electric heating plates are evenly distributed at the bottom of the fermentation zone, with a total coverage area of ​​30-50% (preferably 40%) of the bottom area of ​​the fermentation zone.

[0008] Furthermore, the power of the electric heating plate is 0.1-0.75 KW / m 3 Cow dung residue / h.

[0009] Furthermore, step S1 also includes laying a metal plate with a thickness of 3-8 mm (preferably 5 mm) above the electric heating plate.

[0010] In step S4, the ventilation rate of the intermittent ventilation is controlled to be 10-30 L / min / m. 3 .

[0011] Furthermore, the on-off ratio of the intermittent ventilation is 1:2, wherein the ventilation start time is 5-10 minutes and the stop time is 10-20 minutes (preferably 10 minutes on and 20 minutes off).

[0012] Further, in step S5, the specific method of controlling the start and stop of the electric heating plate through temperature feedback is as follows: when the temperature of the stack body is lower than the first preset temperature, the electric heating plate is started; when the temperature of the stack body is higher than the second preset temperature, the electric heating plate is stopped; wherein, the first preset temperature is 57-59℃, and the second preset temperature is 62-65℃.

[0013] Preferably, the first preset temperature is 59°C and the second preset temperature is 62°C.

[0014] Preferably, the initial carbon-to-nitrogen ratio of the cow dung residue is 23.

[0015] Preferably, the initial moisture content of the cow dung residue is 70%.

[0016] Preferably, the ventilation rate is 10 L / min / m 3 .

[0017] Preferably, the power of the electric heating plate is 0.22 KW / m 3 Cow dung residue / h.

[0018] Furthermore, the molecular membrane is a semi-permeable membrane capable of forming a micro-positive pressure environment.

[0019] By employing the above technical solution, the present invention has at least the following advantages and beneficial effects: (I) This invention provides a method for the rapid and efficient fermentation of cow dung bedding material in windrow and trough fermentation modes under cold winter conditions. By installing heating plates at the bottom of the pile, the cold air output from the bottom aeration pipes is heated. Combined with the upward flow of air within the pile, the entire upper large pile is effectively heated. In winter, when the average daily temperature is around 0°C, conventional piles struggle to achieve normal high-temperature fermentation. This invention can induce the pile to enter a high-temperature period within 3 days and maintain this period until the end of fermentation, achieving excellent fermentation results. The heating plates are controlled by monitoring the pile temperature, automatically shutting off after the internal heat generation reaches the normal fermentation state. This effectively reduces energy consumption, significantly lowers costs, and is easy to operate.

[0020] (II) Regarding environmental impact, this method achieves efficient emission reduction of greenhouse gases such as CH4, NH3, N2O, and NO, as well as harmful reactive nitrogen gases, during the fermentation process. Simultaneously, it enables effective resource utilization of dairy farm manure during winter, preventing large-scale accumulation of manure and reducing environmental pollution. In terms of economic benefits, the safe fermentation production of cow manure bedding material in winter significantly reduces the economic costs associated with the conventional winter purchase of large quantities of rice husks and other materials by dairy farms. Furthermore, compared to the high investment and high electricity consumption associated with some dairy farms using drum fermentation systems, this method is low-cost and highly economical.

[0021] (III) This invention has the synergistic effect of promoting efficient and safe fermentation of manure to produce bedding material and reducing the emission of harmful gases in the environment under cold winter conditions. It is simple to operate and realizes efficient value-added utilization of waste. It has important value and significance for solving the practical problems of manure treatment and resource utilization in dairy farms. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the intelligent heating system for membrane fermentation in a preferred embodiment of the present invention; the left side is a schematic diagram of the high-temperature aerobic fermentation system, and the right side is a schematic diagram of the distribution of heating plates at the bottom of the fermentation pile. Wherein, 1-fermentation platform, 2-ventilation pipe, 3-fan, 4-control cabinet, 5-molecular membrane, 6-fermentation pile, 7-heating plate, 8-iron plate.

[0023] Figure 2 This is the dynamic change of the reactor body temperature in Embodiment 1 of the present invention.

[0024] Figure 3 This represents the dynamic changes in the NH3 emission rate and cumulative emission amount of the reactor in Embodiment 1 of the present invention.

[0025] Figure 4 This illustrates the dynamic changes in CH4 emission rate and cumulative emission amount in the reactor body in Embodiment 1 of the present invention.

[0026] Figure 5This illustrates the dynamic changes in the N2O emission rate and cumulative emission amount of the reactor body in Embodiment 1 of the present invention.

[0027] Figure 6 This illustrates the dynamic changes in NO emission rate and cumulative emission amount in the reactor body in Embodiment 1 of the present invention.

[0028] Figure 7 NO3 in the pile body of Embodiment 1 of the present invention - -N changes dynamically.

[0029] Figure 8 NO2 in the pile body of Embodiment 1 of the present invention - -N changes dynamically.

[0030] Figure 9 The NH4 pile body of Embodiment 1 of the present invention - -N changes dynamically.

[0031] Figure 10 This is the dynamic change of the reactor body temperature in Embodiment 2 of the present invention.

[0032] Figure 11 This represents the dynamic changes in the NH3 emission rate and cumulative emission amount of the reactor in Embodiment 2 of the present invention.

[0033] Figure 12 This illustrates the dynamic changes in CH4 emission rate and cumulative emission amount in the reactor body in Embodiment 2 of the present invention.

[0034] Figure 13 This illustrates the dynamic changes in the N2O emission rate and cumulative emission amount of the reactor body in Embodiment 2 of the present invention.

[0035] Figure 14 This illustrates the dynamic changes in NO emission rate and cumulative emission amount in the reactor body in Embodiment 2 of the present invention. Detailed Implementation

[0036] To address the challenges of proper fermentation of cow manure in cold winter conditions, such as the difficulty in producing qualified cow manure bedding and the emission of large amounts of greenhouse gases and reactive nitrogen gases during fermentation, this invention provides a novel, safe, effective, and low-cost method for improving the fermentation of cow manure bedding in windrows or troughs. This method combines membrane covering and rapid bottom heating.

[0037] The present invention adopts the following technical solution: This invention provides a method for the rapid and safe fermentation of cow dung residue to produce bedding material and the synergistic reduction of greenhouse gas and reactive nitrogen emissions under cold conditions, such as... Figure 1 and Figure 2 As shown, ventilation pipes are installed in the grooves at the bottom of the windrow-type or trough-type fermentation zone; low-power electric heating plates are evenly covered at the bottom of the fermentation zone in a certain proportion; and the initial manure residue is piled up on the fermentation plant area.

[0038] A molecular membrane is covered and fixed on the surface of the manure pile to form a sealed environment; the C / N ratio of the manure is controlled at 20-30, and the initial moisture content is controlled at 60-70%; the ventilation rate of the pile during fermentation is controlled at 10-30 L / min / m. 3 The ventilation mode is intermittent ventilation; the electric heating plate is automatically heated by real-time temperature feedback control. Heating starts when the temperature is below the first preset temperature (57-59℃) and stops when the temperature is above the second preset temperature (62-65℃).

[0039] Based on extensive experiments, this invention has found that by using a bottom-mounted heating plate, combined with reasonable initial C / N ratio, moisture content, and ventilation parameters of the material, rapid start-up of material fermentation and extension of the high-temperature fermentation period can be achieved, enabling safe and efficient fermentation of bedding material in winter, while simultaneously achieving efficient emission reduction of greenhouse gases such as methane, ammonia, nitrous oxide, and nitric oxide, as well as reactive nitrogen gases, during the fermentation process.

[0040] Specifically, a groove is made at the bottom of the fermentation zone along the length of the pile, and ventilation and aeration pipes are installed inside.

[0041] Heating plates are installed at the bottom of the windrow or trough-type stacking area in the fermentation field. The heating plates can be evenly distributed at the bottom of the stack in a certain proportion to achieve an overall coverage of 30-50% of the bottom area; the required power of the heating plates is 0.1~0.75 KW / m. 3 Material / h, optimal is 0.22 KW material / m 3 Based on extensive testing, this invention has found that since the ventilation and aeration pipes at the bottom of the pile are generally located in grooves on the bottom surface of the pile, heating with specific power by arranging heating plates on the fermentation platform at the bottom of the fermentation zone will not affect the operation of subsequent material transfer machinery; at the same time, some heating plates cover the ventilation and aeration pipes, which can heat the cold air intake at the bottom, and as the airflow rises in the pile, a better heating effect is achieved for the entire pile.

[0042] To prevent leachate from affecting electrical conductivity, an iron plate with a thickness of 3mm-8mm, preferably 5mm, needs to be laid on top of the heating plate.

[0043] In winter, the initial C / N ratio of cow manure residue should be controlled between 20 and 30, with an optimal value of 23. Carbon and nitrogen are the energy sources and building blocks for microbial growth and development, playing a crucial role in the fermentation process. A low C / N ratio leads to a relative nitrogen surplus, which microorganisms cannot fully utilize, causing excess nitrogen to be converted into ammonia and volatilize, potentially forming nitrous oxide in subsequent processes. Conversely, a high C / N ratio results in insufficient nitrogen supply, slowing microbial growth and development, leading to slow organic matter degradation and a slow temperature rise in the compost pile.

[0044] In winter, the initial moisture content of the cow dung residue used for bedding fermentation should be controlled at 60-70%, with 70% being optimal. In cold weather, a moisture content below 60% cannot support microbial metabolism, making fermentation difficult to initiate. A higher moisture content will result in an excessively high anaerobic environment, leading to the proliferation of anaerobic bacteria and harmful microbial flora, preventing the production of safe and qualified bedding.

[0045] In winter, the aeration rate of the pile should be controlled at 10~30 L / min / m³. 3 Preferably 10 L / min / m 3 Appropriate ventilation is crucial for the success of aerobic fermentation in winter. If the ventilation is too low, the oxygen provided by the ventilation will not meet the needs of microorganisms, and anaerobic conditions may easily occur in the pile. If the ventilation is too high, although the ventilation can provide sufficient oxygen, the excessive ventilation will increase the heat loss of the pile, making it difficult for the pile to heat up and failing to meet the requirements for harmlessness.

[0046] During the fermentation of bedding material in winter, intermittent ventilation is recommended, with a ventilation-to-stop ratio of 1:2. Ventilation should last 5-10 minutes, followed by a 10-20 minute stop, with the optimal interval being 10 minutes for ventilation and 20 minutes for stop. Continuous ventilation is detrimental to heat accumulation within the pile, making it difficult for the material to heat up; therefore, intermittent ventilation is necessary in winter.

[0047] In this invention, electric heating is used, with a first preset temperature of 59°C and a second preset temperature of 62°C. In the initial fermentation stage, the initial temperature of the pile is low, below 59°C. The heating plate continues to operate to help quickly initiate heating, stopping when the temperature exceeds 62°C. Because the manure bedding material generates a large amount of heat spontaneously after entering the normal aerobic fermentation process, the pile can maintain a high temperature for a relatively long time after the electric heating assists in successfully initiating fermentation. Heating will automatically stop when the temperature exceeds 62°C; however, the pile temperature will continue to rise. As the organic matter in the manure is gradually consumed by the microorganisms during fermentation, the pile's self-generated heat decreases, and the pile temperature will slowly decrease in the later stages. Especially in cold winter conditions, the pile temperature drops rapidly. When the temperature drops below 59°C, spontaneous heating is initiated to prolong the high-temperature period of the pile. This feedback heating design significantly saves energy while being simple to control and easy to operate. The standard for bedding material fermentation requires that the high-temperature period (>55℃) of the bedding material must exceed 7 days. Through extensive research, this invention has found that if the temperature start-stop interval is set at the high-temperature threshold of 55℃, then during the fermentation cooling period, if the pile temperature drops to 55℃ and heating is restarted, the bedding material will be difficult to raise the temperature again and maintain this temperature because a large amount of organic material inside the pile has already been consumed, which is not conducive to safe fermentation.

[0048] After the reactor body is constructed, a molecular membrane is laid on top of the reactor body, ensuring that the membrane completely covers the reactor body. The membrane is then sealed and secured around the reactor body using tires or sandbags. This prevents air leakage during ventilation and aeration, ensuring the formation of a slightly positive pressure environment inside the reactor body.

[0049] Therefore, the present invention has repeatedly explored and coordinated the power and laying conditions of the heating plate, the heating start and stop temperature, as well as the initial C / N ratio, moisture content and ventilation rate of the material before finally achieving the ideal effect.

[0050] In the method of this invention, the C / N ratio of the dairy cow solid manure is 20-30, preferably 23; the moisture content is 60-70% (preferably 65-70%), more preferably 70%; and the ventilation rate is 10-30 L / min / m². 3 The optimal value is 10 L / min / m 3 The coverage of the electric heating plate is 30%-50%, with an optimal coverage of 40%; the power of the electric heating plate is 0.1-0.75 KW / m. 3 Material / h, optimal is 0.22 KW material / m 3 / h; the first preset temperature of the electric heating plate is 57~59℃, with 59℃ being optimal, and the second preset temperature is 62~65℃, with 62℃ being optimal.

[0051] By combining the above-mentioned bottom electric heating method with molecular membrane covering technology, compared with the bedding fermentation pile without electric heating, the conventional cow dung bedding fermentation without the present invention maintained a high temperature period (above 55°C) for 11 days and then quickly cooled down afterward. The treatment group using the present invention extended the high temperature period of the pile until the fermentation was manually stopped, for a total of 18 days. This proves that the present invention can extend the high temperature period.

[0052] Fermentation was carried out for 13 days in an environment with winter temperatures ranging from -4°C to 3°C. Conventional cow manure fermentation without the present invention requires 4-5 days to reach the high-temperature period and maintains a high-temperature period of over 55°C for 3-4 days. The treatment group using the present invention reached the high-temperature period on the 3rd day and maintained it for 11 days until the fermentation was manually stopped, thus achieving safe and efficient fermentation of the bedding material.

[0053] As shown in Table 1, compared with the uncoated and unheated control group (CK), the treatment group using this technology reduced CH4, NH3, N2O, and NO emissions by 85%–91%, 69%–96%, 42%–67%, and 55%–86%, respectively. If only membrane coating (CV) treatment was used, compared with the uncoated and unheated control group (CK), CH4, NH3, and NO emissions were reduced by 68%–79%, 53%–92%, and 8%–27%, respectively, while N2O emissions increased by 13%–165%. If only electric... Compared to the uncoated and unheated control group (CK), heating (HGT) reduced CH4 and NH3 emissions by 25%–41% and 40%–45%, respectively, while increasing N2O and NO emissions by 492%–509% and 218%–442%, respectively. This means that using coating technology alone would increase N2O emissions by 13%–165%, with a relatively low NO reduction of only 8%–27%. However, using electric heating technology alone resulted in increased N2O and NO emissions by 492%–509% and 218%–442%, respectively. This demonstrates the uncertainty of N2O and NO emission reduction when using only a single technology. Therefore, the method of this invention successfully achieved synergistic and efficient emission reduction of greenhouse gases such as CH4, N2O, NH3, and NO, as well as reactive nitrogen gases. This emission reduction effect cannot be achieved by using coating technology or electric heating technology alone. The combination of coating and electric heating drives the transformation of internal mechanisms, achieving synergistic emission reduction of multiple gases.

[0054] Table 1. Emission reduction effects of different technologies on greenhouse gases and reactive nitrogen gases

[0055] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art, and the raw materials used are all commercially available products.

[0056] Example 1: Combined fermentation of dairy cow manure residue under film covering and electric heating at a daily temperature of 7-10℃ and its impact on gas emission reduction. This embodiment includes the following steps: 1. Experimental setup: Four treatments were constructed: no coating and no heating (CK), coating and no heating (CV), no coating and heating only (HGT), and coating and heating (CV+HGT). Two stacks were used to replicate each treatment.

[0057] 2. Layout of electric heating devices at the bottom of the fermentation platform area of ​​the two electric heating groups HGT and CV+HGT: Two electric heating plates are laid on the 3m×2.5m (length×width) fermentation platform area. The heating plate area is 1.2m×1m (length×width) and the heating plate power is 880W. They are laid flat to cover the bottom ventilation pipe and are arranged diagonally.

[0058] 3. Preparation and composting of cow manure residue: Fresh cow manure is subjected to solid-liquid separation. By controlling the screen size or compression efficiency, the moisture content of the solid cow manure residue is controlled at 70%. The residue is then piled on a fermentation platform to a height of 1m, approximately 1189kg (about 4m high). 3 ).

[0059] 4. Set the ventilation rate: Set the bottom ventilation rate to 10L / min / m 3 For materials, intermittent ventilation is used, starting for 10 minutes and stopping for 20 minutes.

[0060] 5. Install an electric heating temperature feedback start-up device. Place the temperature feedback probe at the center of the reactor core to sense temperature changes within the core. Set the first preset temperature to 59℃ and the second preset temperature to 62℃. Heating will start when the core temperature is below 59℃ and stop when it is above 62℃.

[0061] The results showed that during the 20-day fermentation process with an average daily temperature of 7-10℃, the treatment of covered fermentation + electric heating maintained a high temperature of 55℃ for 19 days. On the second day, the pile temperature increased from the initial 13℃ to 59℃. The heating system was started on the first day of fermentation, but stopped working on the second day. It was then restarted on the 15th day and remained running throughout the later stages.

[0062] The control group, which did not use electric heating or cover film, had a temperature of 43.6℃ on the second day and reached 64.8℃ on the third day, indicating a slow fermentation start. The temperature then dropped to 54.8℃ on the 15th day, followed by a rapid decline, reaching 33.4℃ by the 20th day.

[0063] In the control group, which only underwent film covering without electric heating, the temperature reached 55℃ on the second day and 72℃ on the third day, indicating a slow fermentation start. On the 16th day, the temperature dropped to 52℃, and then decreased rapidly, reaching 38℃ on the 20th day. In the treatment group using only electric heating without covering, the temperature remained above 55°C for 19 days throughout the fermentation process. On the second day, the pile temperature increased from the initial 13°C to 58.2°C. The electric heating system was started on the first day of fermentation and stopped working on the second day. From the 15th day onwards, the heating system remained running.

[0064] 6. Analysis of gas emissions, results are as follows: Figures 2-9 As shown: Regarding NH3 emissions, compared to the control (CK), the CV+HGT group reduced cumulative ammonia emissions by 86%–96%, while the CV group reduced emissions by 90%–92% compared to the CK group, and the HGT group reduced emissions by 40%–45% compared to the CK group. This is because ammonification of the bedding material occurs during the heating period, leading to the hydrolysis of organic nitrogen and the rapid accumulation of ammonium nitrogen, resulting in a large amount of ammonia. The CV and CV+HGT groups, due to the membrane barrier and the increased temperature difference between the inside and outside of the membrane forming a sub-membrane water film, absorb the ammonia and allow it to fall back into the reactor core, thus reducing ammonia emissions.

[0065] Regarding CH4 emissions, the CV+HGT group reduced CH4 emissions by 85%~87% compared to the CK group, CV was reduced by 78%~79% compared to CK, and HGT was reduced by 25%~41% compared to CK. Due to the uneven porosity of the pile in the early stage of fermentation, the intense microbial activity in the early stage led to insufficient oxygen concentration in the pile, resulting in increased methane emissions in the early stage. By covering with a semi-permeable membrane, a slightly positive pressure environment can be formed in the pile, which promotes uniform and sufficient oxygen supply in the pile. Therefore, the peak values ​​of CV and CV+HGT are lower than those of other treatments.

[0066] Regarding N2O emissions, the CV+HGT group reduced N2O emissions by 42%~67% compared to the CK group, CV increased by 97%~165% compared to CK, and HGT increased by 492%~509% compared to CK.

[0067] Regarding NO emissions, the CV+HGT group reduced NO emissions by 55% to 86% compared to the CK group, CV reduced NO emissions by 8% to 11% compared to CK, and HGT increased NO emissions by 218% to 442% compared to CK.

[0068] As shown above, compared to the control group (CK) without coating and heating, the treatment group using this technology reduced CH4, NH3, N2O, and NO emissions by 85%–87%, 86%–96%, 42%–67%, and 55%–86%, respectively. However, if coating technology is used alone, N2O emissions increase by 97%–165%, and the reduction in NO emissions is only 8%–11%. Furthermore, if electric heating technology is used alone, N2O and NO emissions increase by 492%–509% and 218%–442%, respectively. This demonstrates the uncertainty of N2O and NO emission reduction when using only a single technology.

[0069] NO3 of CV+HGT processing group - -N and NO2 - The -N content was consistently much lower than that in the CV group, indicating that the combination of coating and heating conditions may have altered the microbial community or activity compared to coating alone, thus affecting NH4+ levels in the CV+HGT treatment. + -N to NO3 - -N and NO2 - The nitrification and denitrification processes of N-N conversion are suppressed, thereby reducing N2O and NO emissions.

[0070] Example 2: Fermentation of dairy cow manure residue under a combined film covering and electric heating plate at a daily temperature of (-4) to 3℃ and its impact on gas emission reduction. This embodiment uses solid-liquid separated cow dung as raw material under daily temperatures of -4 to 3°C, and sets up three treatment groups: uncovered (CK), covered (CV), and covered + electric heating plate (CV+HGT). The bedding material fermentation for each treatment is carried out according to the method in Example 1, and the results are as follows. Figures 10-14 As shown, the highest temperature of the CK group was 63℃, and it remained above 55℃ for 3 days; the highest temperature of the CV group reached 65℃, but the time above 55℃ only lasted for 4 days; the highest temperature of CV+HGT was 66℃, and it remained above 55℃ for 11 days, meeting the requirement of 5-7 days above 55℃ in DB15 / T3041-2023; the cumulative emissions of NH3 by CV were reduced by 53% compared to CK, and those by CV+HGT by 69%; the cumulative emissions of CH4 by CV were reduced by 68% compared to CK, and those by CV+HGT by 91%; the cumulative emissions of N2O by CV increased by 13% compared to CK, and those by CV+HGT decreased by 54%; the cumulative emissions of NO by CV were reduced by 27% compared to CK, and those by CV+HGT by 64%. Compared to traditional bedding material fermentation, the combined fermentation of film covering and electric heating plate used in this invention can effectively reduce the emissions of NH3, CH4, N2O and NO while meeting the hygiene standards of bedding materials.

[0071] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for achieving rapid and safe fermentation of cow dung residue to produce bedding material and synergistic reduction of greenhouse gas and reactive nitrogen emissions under cold conditions, characterized in that, Includes the following steps: S1. Install ventilation pipes at the bottom of the windrow or trough fermentation zone, and install electric heating plates at the bottom of the fermentation zone; S2. The cow dung residue with an initial moisture content of 60-70% and a carbon-nitrogen ratio of 20-30 is piled up in the fermentation zone to form a pile. S3. Cover the surface of the stack with a molecular film and seal and fix the molecular film. S4. Perform intermittent ventilation on the pile body; S5. Monitor the internal temperature of the pile in real time, and control the start and stop of the electric heating plate through temperature feedback to ensure successful fermentation of the pile and extend the high-temperature period of the pile.

2. The method according to claim 1, characterized in that, In step S1, the electric heating plates are evenly distributed at the bottom of the fermentation zone, with a total coverage area of ​​30-50% of the bottom area of ​​the fermentation zone.

3. The method according to claim 1, characterized in that, The power of the electric heating plate is 0.1-0.75 KW / m 3 Cow dung residue / h.

4. The method according to claim 1, characterized in that, Step S1 also includes laying a metal plate with a thickness of 3-8mm on top of the electric heating plate.

5. The method according to claim 1, characterized in that, In step S4, the ventilation rate of the intermittent ventilation is controlled to be 10-30 L / min / m. 3 .

6. The method according to claim 5, characterized in that, The intermittent ventilation has an on / off ratio of 1:2, with a ventilation start time of 5-10 minutes and a stop time of 10-20 minutes.

7. The method according to claim 1, characterized in that, In step S5, the specific method of controlling the start and stop of the electric heating plate through temperature feedback is as follows: when the temperature of the stack body is lower than the first preset temperature, the electric heating plate is started; when the temperature of the stack body is higher than the second preset temperature, the electric heating plate is stopped; wherein, the first preset temperature is 57-59℃, and the second preset temperature is 62-65℃.

8. The method according to claim 7, characterized in that, The first preset temperature is 59°C, and the second preset temperature is 62°C.

9. The method according to claim 1, characterized in that: The initial carbon-to-nitrogen ratio of the cow dung residue is 23; and / or, The initial moisture content of the cow dung residue was 70%; and / or, The ventilation rate is 10 L / min / m 3 ; and / or, The power of the electric heating plate is 0.22 KW / m 3 Cow dung residue / h.

10. The method according to any one of claims 1-9, characterized in that, The molecular membrane is a semi-permeable membrane capable of forming a micro-positive pressure environment.

Images