Problems and Countermeasures of Livestock Manure in Aerobic Composting Fermentation

As a major province in China's livestock industry, Shandong has seen an increasing scale of livestock and poultry breeding year by year. However, with the expansion of breeding scale, the treatment of livestock and poultry manure has become an urgent issue to be addressed. Direct discharge of livestock and poultry manure will pollute soil and water sources, posing a potential threat to human health. Aerobic composting is an efficient method for treating livestock and poultry manure, but there are also some problems in practice. This article will discuss the issues related to the aerobic composting fermentation of livestock and poultry manure in the context of Shandong's geographical location and climatic characteristics, and propose corresponding countermeasures.
Under normal circumstances, some nutrients such as proteins, amino acids, and vitamins cannot be fully digested and absorbed by livestock and poultry, and are excreted along with their feces. When these feces are used in agricultural cultivation, they need to undergo composting treatment and then be converted into Organic Fertilizer. This fertilizer has a certain improvement effect on the soil and can further enhance the yield and quality of crops. Currently, the problem of livestock manure pollution faced by China, as well as how to achieve the reuse of agricultural production resources, can be effectively addressed and resolved through the adoption of aerobic composting fermentation of livestock manure. To a certain extent, the application of technology has effectively promoted the comprehensive and sustainable development of China's agricultural and livestock industry.
1. Analysis of the principle of aerobic composting fermentation of livestock and poultry manure
The so-called aerobic composting fermentation technology for livestock and poultry manure primarily relies on microorganisms such as bacteria, actinomycetes, and fungi that exist in nature. Under an aerobic environment, these microorganisms degrade and transform the organic matter in the manure raw material. Subsequently, high-temperature fermentation treatment is carried out to achieve mineralization, humification, and harmlessness of the organic matter. Ultimately, this results in a fully decomposed fertilizer that is used in agricultural planting and production.
Aerobic composting fermentation is generally also known as high-temperature composting fermentation. Under normal circumstances, it can achieve a compost body temperature of 50°C to 65°C, and the maximum temperature can reach 80°C to 90°C. Various pathogenic microorganisms present in feces can be effectively killed by high temperatures, and the amount of organic matter can be reduced to the greatest extent. Moreover, it can promote the rapid degradation of organic matter to a certain extent and significantly shorten the time required for feces to mature.
The main advantages are: a high degree of harmlessness and high fertility of compost products. Currently, this method is the primary fermentation method used in the treatment of fecal waste.
The aerobic composting fermentation technology for livestock and poultry manure mainly includes three stages: temperature rise, high temperature, and maturity. The principles of these three stages are introduced below:
1.1 The heating stage is the primary stage for conducting aerobic compost fermentation, during which a temperature range of 15℃ to 45℃ is typically maintained. Its function in this stage is to convert easily decomposable organic matter present in the feces into relevant organic nutrients that can be better absorbed and utilized by the soil.
1.2 High-temperature stage: This stage requires a temperature exceeding 45°C. It is a relatively important stage in the entire aerobic fermentation process. During this stage, many high-molecular-weight compounds that cannot be effectively degraded are gradually decomposed and transformed, thereby reducing the quality and volume of composting materials to a certain extent.
1.3 During the decomposition stage, under the influence of high temperature, the original temperature of the compost will begin to continuously decrease. In this process, lignin and humus, which are not easily degraded, will coexist, greatly increasing the content of various nutrients in the compost, but at the same time reducing the corresponding moisture content.

2. The problem of livestock and poultry manure in aerobic composting fermentation
2.1 Low temperature aerobic composting requires ensuring that the temperature inside the heap is within a suitable range, otherwise it will affect the fermentation effect of the compost. Due to Shandong's location in the northern region, the winter temperature is relatively low and the climate is dry, which makes it easier for the temperature inside the compost pile to decrease, resulting in slow composting.
2.2 Excessive moisture content is a key factor causing poor fermentation efficiency of aerobic composting of livestock and poultry manure. The Shandong region has less precipitation throughout the year and dry air, so livestock and poultry manure is prone to water shortage during composting, resulting in high moisture content.
During the aerobic composting process, due to the need for breeding and reproduction of composting bacteria, certain gases such as ammonia and hydrogen sulfide will be produced, and their odors will affect the surrounding environment and residents' health. The livestock and poultry breeding density in Shandong region is relatively high, with a dense population, and the problem of odor disturbance is particularly prominent.
During the aerobic composting process of livestock and poultry manure, excessive wetting of compost is a common problem. Especially in the high-temperature and humid environment of Shandong region in summer, improper handling can easily lead to excessive moisture in compost, thereby affecting the quality and effectiveness of compost fermentation. The moisture content of compost has a significant impact on aerobic fermentation. If there is too much moisture in the compost, it will cause poor ventilation inside the compost pile, and oxygen cannot enter the pile smoothly, thereby preventing aerobic bacteria from carrying out normal metabolic activities in a sufficient oxygen environment, which will have an impact on the entire aerobic composting reaction process. In addition, excessive moisture also makes it difficult for the accumulated heat during the composting fermentation process to diffuse and release, resulting in an increase in the internal temperature of the compost, further affecting the quality and efficiency of the compost. For example, in the summer in Shandong region, high temperatures and humidity can easily lead to excessive moisture in compost, making it difficult to maintain a suitable ventilation state.
2.5 Water overflowing the heap In the process of aerobic composting of livestock manure, if extreme weather such as rainstorm is encountered, it is easy to overflow the heap. This not only affects the growth and reproduction of aerobic bacterial communities, but also leads to problems such as poor ventilation inside the pile and excessive moisture in the compost, thereby affecting the quality and efficiency of the aerobic composting reaction process. Rainstorm weather has a great impact on Shandong area, so measures should be taken to prevent water from overflowing the pile during composting.
3. Countermeasures for livestock and poultry manure in aerobic composting fermentation
3.1 Countermeasures for Low Temperature 3.1.1 Solar Heating Solar energy is a free, clean, and Renewable Energy source that can directly use solar radiation to heat the stack. Usually, solar panels or semi transparent films can be installed outside the stack to focus solar radiation onto the surface of the stack after passing through the panels or films, thereby achieving heating inside the stack. This method is simple and easy to implement, and it is also beneficial for environmental protection and energy conservation. During winter, pressurized ventilation can be used to enhance the airflow inside the reactor, thereby increasing the temperature of the reactor. Specifically, exhaust devices such as axial fans or electric fans are installed on both sides or around the stack to enhance the airflow inside the stack through pressurized ventilation, thereby achieving the goal of increasing the temperature of the stack. 3.1.3 Adjusting Material Proportions For low-temperature reactors, the internal heat value of the reactor can be increased by adjusting organic matter, carbon nitrogen ratio, or moisture content. For example, adding an appropriate amount of straw, sawdust, and other materials to the pile can control the moisture content and provide sufficient hard cellulose and carbon sources for aerobic bacterial communities to increase the calorific value and aerobic fermentation reaction rate inside the pile. When selecting compost fermentation microbial communities, it is necessary to optimize and adjust them according to the actual situation. In response to the slow growth of aerobic bacterial communities inside the reactor under low temperature conditions in winter, aerobic bacterial communities with high cold resistance, such as psychrophilic bacteria, pseudomonas, etc., can be selected. These bacterial communities can grow and reproduce normally at lower temperatures and effectively accelerate the aerobic fermentation reaction.
3.2 Countermeasures for excessive moisture content in compost can be achieved by adjusting the material ratio and increasing the appropriate amount of straw to control the moisture content. Adjusting the material ratio refers to adding other organic substances such as straw, sawdust, etc. to the pile to achieve the appropriate moisture content. Meanwhile, humidifiers can also be used to increase the moisture content of compost. According to the actual situation, increasing the appropriate amount of humidity and moisture can be achieved not only by spraying humidifiers, but also by covering materials and other methods to effectively control moisture.

3.3 Measures to address odor disturbance include measures such as isolation belts and covering materials to reduce the area of odor dispersion and minimize the spread of odor. Adding a certain amount of solid carbon dioxide or wood chips during composting fermentation can effectively absorb and reduce the production of odorous substances such as ammonia and hydrogen sulfide. In addition, strengthening the control of aerobic fermentation reactions and avoiding the production of odorous gases under anaerobic conditions is also a key solution to the problem of odor disturbance.
3.4 Countermeasures for excessive moisture in compost 3.4.1 Adjusting the proportion of materials can be done by adjusting the proportion of other organic matter appropriately based on the moisture content in the compost. For example, with the support of biotechnology, carbon rich substances such as optimized soybean hulls and sawdust can be used to replace some livestock and poultry manure. These materials not only provide sufficient food for aerobic bacteria, but also have the function of absorbing water and removing moisture. During the composting fermentation process, if it is found that the ventilation effect inside the compost pile is poor, a certain amount of humidifying agent can be added in moderation to increase the moisture content of the compost. Humidifiers themselves are organic substances that are easily soluble in water. When mixed with compost materials, they can quickly absorb surrounding moisture, maintaining a suitable moisture content inside the pile. 3.4.3 Covering materials shall be covered to prevent the compost from being eroded by rainstorm or exposed to direct sunlight, thus affecting the moisture content inside the pile. The selection of covering materials should be determined based on the specific environment and situation. For the high-temperature and humid environment in Shandong region, it is more suitable to use materials such as plastic film or sunshade nets with better coverage performance. 3.4.4 Strengthening ventilation management: For excessively humid reactors, the oxygen content inside will decrease, so it is necessary to strengthen ventilation management and enhance the air circulation inside the reactor. Specifically, multi-stage ventilation method can be used, utilizing exhaust equipment for natural ventilation or other auxiliary ventilation methods such as electric fans and axial fans.
In summary, excessive moisture during aerobic composting of livestock and poultry manure is a problem that deserves attention. Multiple measures can be taken to address this issue, including adjusting material ratios, spraying humidifiers, covering materials, and strengthening ventilation management.
3.5 Countermeasures for Water Overflow over the Pile Body 3.5.1 Adjustment of Pile Body Structure When designing and constructing the pile body, drainage facilities should be added or a certain slope design should be adopted according to the actual environment and climate characteristics, in order to naturally discharge rainwater. In addition, to ensure the normal growth and reproduction of aerobic bacteria, a layer of covering material needs to be set on the surface of the pile to prevent rainwater from directly penetrating into the interior of the pile. 3.5.2 Emergency Measures: In the event of an emergency situation where water overflows the reactor, timely emergency measures must be taken. For example, covering the pile with large waterproof cloth or plastic film to prevent rainwater from entering; Excessive rainwater can be drained using devices such as water pumps; Or temporarily transfer the upper part of the pile to a safe location, etc. When selecting composting materials, it is advisable to avoid selecting materials that contain a large amount of difficult to degrade substances, such as wooden boards, plastic bags, and other garbage. These garbage materials not only affect the growth and reproduction of aerobic bacteria, but also block drainage channels and ventilation holes, exacerbating the phenomenon of water overflowing the pile.
The final metabolic product in livestock and poultry farms is livestock manure, which contains many putrefactive substances such as carbohydrates and nitrogen-containing compounds. When carrying out composting fermentation work, various microorganisms will extract nutrients from the above substances to ensure smooth metabolism. In addition, various processing by-products will be used as auxiliary materials For Composting fermentation, such as crop straw, husks, sawdust, Chinese medicine residue, or peanut shells. The main function is to ensure the supply of carbon sources required for composting fermentation and to regulate the water content and carbon to nitrogen ratio.
In addition, it can effectively improve the structural state of the compost pile and promote gas circulation during the composting fermentation process. There are many highly active exogenous strains in the fermentation culture, such as bacteria, actinomycetes, and fungi. In addition, they also have strong reproductive ability and fast decomposition rate. The organic matter decomposition in compost fermentation can be effectively enhanced by the use of exogenous fermentation strains, thereby greatly reducing the composting time. Monitoring and regulating the state of aerobic composting reaction in a timely manner is one of the important means to ensure the effectiveness of composting treatment. In case of sudden situations such as water overflowing the pile, it is necessary to adjust the internal ventilation, moisture content, and microbial species of the pile in a timely manner to restore the normal state of compost fermentation. In fermentation reaction monitoring, temperature, pH, and oxygen content are controlled. The most suitable composting fermentation temperature is mainly between 50oC and 65 ℃. In the process of composting fermentation, high-temperature bacteria have higher efficiency in degrading organic matter than medium temperature bacteria. However, during this process, it is necessary to fully control the temperature of composting fermentation. If the temperature is too high, microorganisms are prone to death. If the temperature is too low, it increases the time for compost to mature, and it is necessary to ensure continuous composting and fermentation treatment. In order to effectively enhance the growth and metabolic activity of microorganisms, it is usually necessary to ensure the suitability of pH during the composting stage. In addition, it can greatly enhance the nitrogen fixation effect of microorganisms to a certain extent. Under normal conditions, it is necessary to ensure a pH of 6.5-9.0. When carrying out aerobic composting work, the activity intensity of microorganisms will have a certain impact on oxygen, thereby affecting the fermentation rate of organic matter. If the oxygen content is below 8%, anaerobic fermentation usually occurs, resulting in the generation of many odors. Therefore, in carrying out composting fermentation, it is necessary to ensure that there is an oxygen concentration condition exceeding 10%. 3.5.5 Strengthening the construction of drainage facilities In order to prevent problems such as water overflowing the pile, the construction of drainage facilities can also be strengthened. For areas with dense livestock and poultry breeding, certain drainage ditches and sand dams can be set up outside the breeding site to effectively divert rainwater. At the site of aerobic composting of livestock and poultry manure, pumping equipment can be installed to monitor and regulate the drainage situation. The construction and application of drainage facilities should be based on actual needs, optimizing and improving the process of treating livestock and poultry manure, and comprehensively utilizing and treating sewage to improve the comprehensive treatment effect of livestock and poultry manure. In the process of treating livestock and poultry manure, based on the principle of aerobic composting, drainage facilities are improved and optimized to reduce the impact of moisture on aerobic composting fermentation.
Fecal waste, auxiliary materials or additives mainly provide water requirements for aerobic composting fermentation work. In addition, water can also be added separately to it. The role of water in aerobic composting fermentation is to soften the raw materials and dissolve the organic matter present in them, thereby providing assistance for subsequent decomposition. Secondly, in actual fermentation, the growth and reproduction of microorganisms, as well as metabolism, require the assistance of water, thereby ensuring the uniformity of nutrients and bacterial cells, providing important support for temperature regulation in subsequent composting fermentation. Therefore, water overflowing the pile is a common problem in aerobic composting of livestock and poultry manure. In order to avoid and solve this problem, it is necessary to optimize and improve from multiple aspects, including pile structure, emergency measures, selection of compost raw materials, monitoring of fermentation reactions, and strengthening the construction of drainage facilities, in order to ensure the normal progress of aerobic composting reactions and improve the effectiveness of livestock and poultry manure treatment.

4. Conclusion
Fermentation technology has been widely used in Chinese herbal preparations and vaccines to enhance or increase the effective ingredients, enabling them to exert a wider range of effects. Among them, the fermentation of livestock and poultry manure is currently the most widely used field of this technology. The fermented material needs to be effectively treated after completing the fermentation of livestock and poultry manure, in order to ensure that the quality of the final compost product meets relevant standards and requirements. The general follow-up processing work is mainly achieved through processes such as drying, crushing, granulation, screening, packaging, and finished products, which need to be adjusted according to the actual situation during operation. According to the relevant provisions of the Technical Specification for Pollution Control Engineering in Livestock and Poultry Breeding Industry, it can be known that the relevant compost products need to meet the following requirements.
During the preservation process of relevant compost products, it is necessary to ensure a moisture content of less than 30%. If the compost product is bagged, the moisture content needs to be controlled below 20%;
Ensure that compost products have a salt content of 1% to 2%; If compost products are considered finished products, they need to have a tea brown or black appearance, while ensuring that there is no foul odor present, and have a relatively loose texture, usually with the same odor as soil.
Livestock manure is an important organic fertilizer resource, and aerobic composting is an effective treatment method. However, in practice, due to the influence of Shandong's geographical location and climate characteristics, there are some problems with the aerobic composting fermentation of livestock and poultry manure. To solve these problems, methods such as solar heating, increasing appropriate humidity and moisture, and adding solid carbon dioxide can be used to optimize the fermentation reaction conditions of aerobic composting, thereby improving the efficiency and quality of livestock and poultry manure treatment.