Eight major bio organic fertilizer technology sharing - how to achieve the resource utilization of livestock and poultry manure?

China is a major livestock and poultry breeding country, and livestock manure has become an indispensable part of agricultural non-point source pollution. Its treatment effect is closely related to environmental protection, soil improvement, emission reduction, etc. The challenge facing the development of ecological agriculture is to seek alternatives to chemical fertilizers. Therefore, it is necessary to promote the reuse of aquaculture resources, strengthen awareness of green, efficient and environmental protection, and achieve maximum benefits.

01
livestock and poultry manure
Livestock and poultry manure includes animal manure, urine, as well as wastewater and waste generated during the breeding process. In some economically underdeveloped areas, due to factors such as people's ideological awareness, technological conditions, and government attention, the disposal of livestock and poultry manure is not thorough, resulting in environmental pollution hazards and resource waste.
According to the second pollution source statistics, the amount of livestock and poultry manure in China exceeds 3 billion tons. These manure contain a large amount of organic matter, total phosphorus, total nitrogen, and various metal elements such as K, Cu, Zn, Cr, Ni, Hg, etc. They are not only valuable resources for improving soil fertility, but also raw materials for industrial material development and synthesis. Because these feces contain a large amount of microorganisms, bacteria, organic matter, and elements such as N and P that have not been digested and absorbed by the body, and are discharged without treatment, they not only pollute the environment and waste resources, but also increase the mortality rate of livestock and poultry, and even pose a threat to people's healthy lives.
02
Resource utilization mode
At present, the resource utilization mode of livestock and poultry manure in China is mainly based on the combination of planting and breeding for fertilizer and energy utilization, supplemented by feed and base material utilization. Regardless of the utilization method, the final product is returned to the field to improve soil quality and provide fertility, as shown in the following figure.

Usually, anaerobic fermentation or aerobic fermentation is carried out using the action of microorganisms. The energy generated by aerobic fermentation is mainly in the form of thermal energy, which has the advantage of relatively simple process, but the recovery and utilization of thermal energy is not convenient. Anaerobic fermentation, such as biogas power generation, mainly collects combustible gas methane for utilization. In addition to the cumbersome anaerobic process and management, as well as high investment costs, anaerobic microorganisms also produce methane, making it a promising New Energy source.
Livestock and poultry manure also contains various nutrients such as vitamins, minerals, amino acids, and crude fiber. Especially for poultry, due to their short digestive tract, most of the nutrients are not digested and absorbed. After simple processing, they can meet the standards of livestock and poultry feed. Especially chicken manure, which contains a large amount of undigested nutrients and some unknown factors that promote animal growth, can be further processed into unconventional feed resources, which can be used to feed pigs, as well as for the breeding of fish, mealworms, maggots, earthworms and other animals. These animals themselves are also very good animal feed.
Basic material utilization refers to the direct use of livestock and poultry manure as a base material or its addition as an auxiliary material to improve the quality of the base material. Together with important raw materials such as straw for soilless cultivation, it can be used as a base material for the cultivation of edible fungi, which can reuse manure and establish a multi-level ecological agriculture system. However, at present, livestock and poultry manure generally has problems such as excessive heavy metals, difficulty in cultivating edible plants, and lack of production process standards, resulting in uneven product quality.

03
Fertilizer and energy utilization technology
（1） Storage tank fermentation technology
A storage tank is a mixture of livestock and poultry manure, flushing water, and a small amount of dispersed feed, which is collected in an open, closed, or semi closed storage condition (liquid manure) and accompanied by aerobic or anaerobic fermentation processes. At present, most small-scale breeding farms (households) use this technology to store manure. Due to the direct return of unfermented feces to the field, soil hypoxia can occur, leading to seedling burning and heavy metal pollution, which is also detrimental to plant nutrient absorption. Therefore, microbial agents are usually added as base fertilizers to ferment the feces in the storage tank for no less than 3 months.
（2） Dry wet separation treatment technology
Dry wet separation, also known as solid-liquid separation, refers to the separation of solid suspended solids, feces, and urine wastewater in the collection and treatment of livestock and poultry manure. Generally, separation techniques such as chemical settling, screening, and squeezing are used. There are two types of dry wet separation: natural separation and artificial dry manure cleaning. Natural separation requires livestock and poultry sites to reserve a certain slope or set up drainage ditches, leaky floors, etc., forming a dry manure collection pool and rain and sewage diversion facilities to separate manure and urine; Artificial dry wet separation requires the use of dry wet separation equipment for centralized processing. The separated solid material can be bagged as high-quality fertilizer, and the separated liquid material can enter the biogas digester for fermentation and gas production. The advantages of a dry wet separator are simple operation, small footprint, high processing efficiency, high degree of automation, and high return on investment.
（3） Membrane coverage treatment technology
Membrane covering technology refers to the use of special composite membranes to cover the fecal environment for aerobic fermentation. Through manual control, the concentration of pollutants emitted from the material pile is reduced to meet certain requirements for material and energy exchange with the surrounding environment. To ensure the fermentation effect, a suitable aerobic fermentation closed environment is constructed, and a semi permeable functional membrane is covered on the conventional tank reactor to achieve the treatment effect. Nowadays, pig farms commonly use high-density polyethylene film fermentation method. This black film covers the middle of the manure, which can effectively prevent seepage and avoid the foul odor of sewage emitted in the air; There is also polymer nanofilm covered fermentation, equipped with oxygenation equipment and IoT control system, which makes management more mechanized and intelligent.
（4） High temperature fermentation tank treatment technology
The working principle of the livestock and poultry manure fermentation tank is to mix livestock and poultry manure and biomass (straw, sawdust, etc.) in a certain proportion under a certain temperature, humidity, and sufficient oxygen environment, so that microorganisms can rapidly reproduce and decompose organic matter, releasing a large amount of heat, killing a large number of harmful substances such as pathogenic bacteria and parasite eggs in the manure, and at the same time, creating a biological odor on the emitted gases such as ammonia and carbon dioxide. At present, vertical fermentation tanks, horizontal fermentation tanks, mechanical agitation tanks, fully enclosed fermentation tanks, etc. are widely used in the market. The clinker processed by this technology can be used directly as fertilizer or as raw materials for producing compound Organic Fertilizers. Fermentation tanks are usually buried below 1.5 meters underground, which is convenient to operate and use, and has advantages and characteristics such as land conservation, long service life, economic applicability, and no leakage.

（5） Composting and composting technology
Composting is a type of biological fertilizer that decomposes organic matter in manure into humus through aerobic methods. It is a mixture of manure, soil, and minerals that is accumulated and fermented under high temperature conditions. The principle is to utilize the action of multiple microorganisms to humify the organic matter in feces and convert it into soluble nutrients. Generally, it can be fermented and decomposed under high temperature fermentation conditions of 50-60 ℃ for 45-60 days. There are currently four mature composting processes. One is stack composting, which refers to the process of stacking manure raw materials into stacks and promoting manure fermentation through flipping. The second is static composting, which is a composting method composed of natural ventilation or the addition of ventilation equipment on the basis of strip pile composting. The bottom of the pile can be equipped with a traditional aeration system. The third method is trough composting, which is generally carried out in a closed fermentation workshop environment. It uses trough flipping, throwing and moving materials, and arranges an aeration system to achieve rapid maturation of the materials. The fourth is reactor composting, which refers to the use of composting reaction equipment and measures such as aeration and stirring to rapidly ferment and mature manure, thereby converting livestock and poultry manure into organic fertilizer.
Composting, also known as heap composting, is based on the same principle as composting technology. It usually involves concentrating liquid manure from livestock and poultry in a pit and covering it with a layer of straw, humus, and other materials For Composting for more than 3 months. Semi open composting ponds are the most common for small and medium-sized farmers, requiring the composting pit to be rainproof, anti-seepage, and leak proof.
（6） Oxidation pond treatment technology
Oxidation pond, also known as stabilization pond, is based on the principle of anaerobic biological fermentation to degrade organic matter and achieve the purpose of manure purification. The process is essentially the conversion of dissolved organic pollutants in livestock and poultry manure into inorganic and solid organic matter - bacteria and algae cells. Aerobic bacteria utilize oxygen in water during this process to oxidize and decompose organic pollutants into inorganic substances such as CO ₂, NH ₄⁺, and PO ₄³ ⁻ through aerobic metabolism. Through photosynthesis of algae, new algal cells are formed, releasing oxygen and providing it to aerobic bacteria during the metabolic process. As a result, algae, aerobic bacteria, organic debris, and pond water together form a aquatic ecosystem. Organic pollutants are oxidized and decomposed into organic pollutants through aerobic metabolism, purifying the wastewater entering the pond and completing the circulation and transfer of substances and energy in the system. Oxidation ponds have the advantages of low investment costs, easy maintenance, and efficient manure treatment, and have certain promotional value.

spreading crop straw and other substrate materials flat in the enclosure, mixing and fermenting them with livestock and poultry manure, urine, and waste, and cleaning them after a certain period of time includes ordinary bedding breeding, microbial fermentation beds, and ex situ fermentation. In the process of fermentation, microorganisms can not only effectively degrade organic substances in feces, kill pathogenic microorganisms and parasite eggs, reduce the incidence rate of livestock and improve the comfort of livestock and poultry. Microbial fermentation bed is formed by laying sawwood, straw, probiotics and other raw materials to form a microbial fermentation bed, and then raising livestock and poultry on the fermentation bed. It is widely used in some pig and chicken farms, but its disadvantage is that it cannot effectively disinfect the fermentation bed because disinfectants will have a bactericidal effect on the microbial community. Off site fermentation, also known as off site fermentation, generally consists of a sewage collection tank (sewage pipeline), a fermentation tank, padding and spraying equipment, a turning rake equipment, and other parts. When the fecal matter is collected and enters the fermentation tank, microbial agents need to be added, and measures such as turning arches need to be taken to fully mix it with feces to improve fermentation efficiency; Due to the avoidance of contact between the fermentation bed and the animal body, ectopic fermentation solves the negative impact of ineffective disinfection of the enclosure, and also has the advantages of mechanization and large-scale operation.
（8） Anaerobic fermentation technology
Under the action of microorganisms, anaerobic fermentation technology is used to decompose organic matter into combustible gases such as methane, which are collected and utilized as new energy sources. This method is widely used, especially in large and medium-sized farms or breeding intensive areas, but the disadvantage is that it occupies a large amount of space. Fermentation facilities can be used to ensure stable fermentation temperature. It is recommended that the anaerobic fermentation temperature be between 30-60 ℃ and the fermentation period be no less than 8 weeks. Under the action of microorganisms, pathogens and parasites in feces are killed, effectively blocking the spread of parasites and reducing the spread of pathogens.
The biogas model first needs to collect and store the raw materials required for anaerobic digestion, followed by improving the base materials. In the anaerobic digestion stage, primary digestion and secondary digestion are carried out successively to form an anaerobic digestion cycle. Biogas is extracted from anaerobic digestion process, mainly composed of carbon dioxide and methane. The residue generated during anaerobic fermentation can be used as beneficial fertilizer for soil fertilization after treatment. The advantage of biogas power generation is to provide high-quality energy, convert manure into diverse energy sources for output and reuse. Anaerobic digestion has significant economic and ecological benefits, reducing carbon emissions, air and water pollution in aquaculture, saving feeding costs, and ultimately improving soil fertility.