Reduction and harmless technologies
Reduction is the use of certain technologies to reduce the volume or mass of the waste to facilitate transportation and disposal.
Harmlessness is the elimination or removal of harmful substances, such as sterilization and deodorization, through certain technologies.
(1) Incineration method
Because animal waste contains organic matter, similar waste incineration treatment technology is used to ash it to achieve the purpose of reducing and killing harmful pathogens. However, harmful gas is generated during the process, and many nutrients are lost. At the same time, it consumes a lot of energy and has a large investment, so it is not easy to promote.
(2) Drying method
The drying method uses heat energy, solar energy, wind energy and other energy to treat livestock and poultry manure, so that animal waste can remove most of the water in a certain period of time. The purpose of drying is not only to reduce the moisture in the feces, but also to achieve the effects of deodorization and sterilization. Therefore, dried animal and poultry manure greatly reduces environmental pollution. In addition, dried animal manure can be processed into granular fertilizer or used as feed for livestock and poultry, which has multiple uses.
According to different heat sources and heating methods, the drying methods are divided into natural drying, high-temperature rapid drying, and mechanical drying.
Chickens have a short digestive tract and poor absorption capacity. Most of the nutrients in the feed (about 70%) are not digested and are excreted in the form of feces. Therefore, chicken manure is often processed at home and abroad. Although the drying method has many advantages, it can only focus on solving a certain aspect of the problem, and cannot consider the problem from the perspective of the entire ecological environment system, so it is difficult to fundamentally solve the problem of environmental pollution.
(3) Deodorization method
At present, the odorous gases generated from livestock manure are mainly attributed to sulfur compounds, nitrogen compounds, volatile fatty acids and ketones. It is generally believed that ammonia, carbon dioxide, methane and hydrogen sulfide are the main causes of air pollution and odor.
Formalin, ethylene, sodium bicarbonate, methyl bromide and other agents were added to the livestock and poultry manure to kill the germs and reduce the volatilization of ammonia. The processed products were used to feed ruminant livestock. However, the large one-time investment in chemical treatment technology and high product costs make it difficult to obtain good economic benefits and cannot be accepted by the market smoothly.
Generally speaking, technologies such as drying and deodorization have only achieved the purpose of waste reduction and harmlessness, while comprehensive technologies can not only reduce waste and reduce harmlessness, but also use the resources in it. Oxygen compost, fermentation, etc.
(1) Composting method
Composting is one of the effective methods for treating various organic wastes. It is to stack solid organic wastes such as animal manure in a certain proportion, adjust the C / N ratio of the compost materials, control the appropriate moisture, temperature, oxygen and pH. Biochemical reactions under the action cause natural decomposition, and as the temperature of the compost increases, the pathogens, eggs and pupae are killed. The treated material is used as a high-quality organic fertilizer.
Biological treatment technology is a technical method that uses microorganisms to decompose organic matter in livestock and poultry manure so as to achieve harmlessness and resource utilization. It is an effective and economical technology method for treating livestock and poultry manure. Utilizing microorganisms widely existing in the natural world and controlling appropriate conditions will not only enable the organic matter in livestock and poultry manure to be fermented and rotted to produce organic fertilizer, but also to obtain biogas. According to the different requirements of the microorganisms acting on oxygen in the treatment process, biological treatment can be divided into anaerobic biological treatment and aerobic biological treatment.
(3) Anaerobic biological treatment method
The anaerobic biological treatment method refers to a biological treatment method that mainly decomposes and stabilizes the organic matter in livestock and poultry manure by anaerobic microorganisms without providing free oxygen, that is, anaerobic fermentation method. Anaerobic treatment is currently an important environmental technology for the treatment of livestock and poultry manure.
Its advantage lies in the fact that it can obtain available energy and materials while eliminating the environmental pollution of livestock and poultry manure. It has the common point with aerobic treatment that it can be completed with the participation of microorganisms.
The use of natural or inoculated microorganisms converts organic matter to carbon dioxide and biogas under hypoxic conditions. The advantage is that the malodor of the final product is reduced, and the biogas produced can be used as an energy source. The disadvantage is that the ammonia volatilization loss is large, and the volume of the treatment tank is large.
(4) Aerobic biological treatment method
The aerobic biological treatment method refers to a biological treatment method that mainly decomposes and stabilizes the organic matter in livestock and poultry manure under the condition of providing free oxygen, mainly aerobic microorganisms. For example, artificial wetland, solar greenhouse fermentation, dynamic aerobic fermentation, etc. High temperature aerobic composting method is one of the most promising, widely used and most promising methods for the treatment of livestock and poultry manure. It is an effective method for the harmless and safe treatment of livestock and poultry manure.
The advantage of using high-temperature aerobic composting method to treat livestock and poultry manure is that aerobic high-temperature fermentation has the characteristics of fast decomposition of organic matter, complete degradation and uniform fermentation. The fermentation temperature is generally 55 ~ 65 ℃, the dehydration speed is fast, the fermentation period is short, and the organic matter is completely decomposed. The moisture content can be reduced to 40% to 50% at about 15 days, and the killing effect of pathogenic bacteria, parasite eggs and weed seeds is also good. The final product treated has less odor and is drier, which is easier to package and fertilize. However, the appropriate moisture content of the initial fermentation should be 55% to 65%. Ventilation or stacking is required. At the same time, the volatilization of ammonia during the fermentation will produce odors, reduce fertilizer efficiency, and require large compost sites.