Over the past decade, Chinas animal husbandry industry has developed rapidly, with an average annual growth rate of up to 10%, and is mainly characterized by large-scale and intensive management. The number of pigs, cows, and chickens raised is among the highest in the world. The rapid development of animal husbandry has made great contributions to ensuring market supply and improving peoples living standards, but at the same time, it has brought serious environmental problems. In recent years, the government has invested heavily in research on the treatment of livestock and poultry manure. Among them, fermenting livestock and poultry manure into organic fertilizer is a good method to solve pollution problems and increase fertilizer sources.

1、 The pollution of livestock and poultry manure to the environment

In livestock and poultry breeding, the pollutants generated are the excrement of livestock and poultry, which is the main source of environmental pollution caused by breeding. China only raises pigs, with a daily manure output of 2.91 million tons and an annual manure output of 1.062 billion tons. The daily discharge of chicken manure is 380 million kilograms, and the annual discharge is 169 million tons. Due to the lack of corresponding treatment technology and facilities, a large amount of pig manure is directly discharged into rivers, at most simply pushed into fields. It has caused significant pollution to the environment.

1. Nitrogen and phosphorus pollution

Animal manure not only causes waste of nutritional resources, but also contributes to environmental nitrogen and phosphorus pollution. According to calculations, a pig farm with 10000 pigs releases 100 tons of ammonia and 30 tons of phosphorus into the environment annually. Every year, pig manure alone can discharge 1.062-2.124 million tons of phosphorus nationwide. If discharged indiscriminately without harmless treatment, it will cause great pollution to surface water and groundwater. The nitrogen in untreated animal manure is directly or oxidized into nitrate, which pollutes surface water and groundwater through runoff and infiltration. The organic pollutants contained in it can flow into the water and consume a large amount of dissolved oxygen, causing eutrophication and turning the water black and odorous.

2. Pathogen contamination

Feces, urine, and wastewater contain a large amount of harmful microorganisms, pathogenic bacteria, and parasitic eggs. The indiscriminate disposal of untreated animal manure first poses a threat to the livestock and poultry in the farm, as well as the surrounding breeding industry, and in severe cases can result in catastrophic consequences. At the same time, many pathogens are also pathogens of human infectious diseases. Pathogenic microorganisms in animal manure and excrement can spread diseases by contaminating soil, water sources, atmosphere, and agricultural and livestock products.

3. Heavy metal pollution

With the large-scale and intensive development of the livestock and poultry industry, the feed industry has also developed rapidly. Feed contains high amounts of trace element additives such as copper, iron, and zinc. Copper can reach up to hundreds of mg/kg, while zinc can reach thousands of mg/kg. According to reports, the annual use of trace element additives in China is 150000 to 180000 tons, but due to their low biological potency, about 100000 tons are not utilized by animals and are discharged with animal feces, polluting the environment.

2. Producing organic fertilizer is an important way to solve the pollution of poultry and livestock manure

The effective way to treat livestock and poultry manure is through biological treatment, which decomposes, decomposes, and converts the manure into odorless and harmless organic fertilizer. In the entire agricultural ecosystem, due to the shift of agricultural industry structure from grain and oil production to efficient agriculture, in order to increase production and income, most places tend to use chemical fertilizers instead of organic matter input, resulting in soil structure damage, reduced biological activity, land degradation, decreased agricultural product quality, and increased harmful substances. Therefore, using livestock and poultry manure to produce organic fertilizer can not only solve the problem of manure caused by large-scale breeding, but also distribute nutrients evenly throughout the entire agricultural ecosystem. Realizing the resource utilization of livestock and poultry manure is the key to solving this problem; The transfer of organic fertilizer from point (intensive breeding farms) to surface (vast areas lacking fertilizer) is the way to solve this problem.