How to turn pig manure into profitable organic fertilizer

The basic principle of organic fertilizer production is to mix organic materials such as excrement and urine with wood bran and straw fragments for natural fermentation or aerobic fermentation with microorganisms to convert organic matter into stable humus. Different manure cleaning methods and processing scales have slightly different methods.
To make organic fertilizer, first change the water soaked manure:
Moisture is an important indicator in organic fertilizer production. Therefore, the dry cleaning method is more suitable for the production of organic fertilizer. The first step in composting fermentation is to adjust the water content. The most suitable water content is 50%-60%. Too dry or too wet will affect the aerobic fermentation process. If a fattened pig produces 396 kg of pig manure per year, the utilization rate of dry and clear manure can reach 70%-80%, while the water content of pig manure obtained by soaking manure or water flushing manure and then separating solid and liquid is high, and the utilization rate is less than 50%. Moreover, nutrients dissolve in water, which also reduces fertilizer efficiency and reduces the value of organic fertilizer production. It is difficult to separate the solid and liquid in the way of soaking manure in water. Even if it is separated, the nutrients of pig manure will be lost and the fertilizer efficiency will be low. Therefore, some pig farms with water-soaked manure have been transformed into the mode of flushing manure with water.
The “high-bed fermentation type ecological pig raising model” directly combines the pig house with the organic fertilizer production workshop. Treating feces and urine together saves space, manpower and material resources. The pig house has a two-story structure. The pigs on the second floor adopt temperature-controlled ventilation equipment and a fully slatted floor structure.
During the pig production process, there is no flushing, and the pig manure and urine produced fall into a layer of litter through the slatted board; the height of the first floor of the pig house is 2.5-2.8m, and the bedding such as wood bran is laid to absorb the pig manure and urine. The thickness is 60-70cm, and the compost turner will automatically turn the compost to ferment the semi-decomposed organic fertilizer, and then transfer it to the organic fertilizer workshop for further fermentation.
Aerobic fermentation is the core:
After the manure is collected, it will be composted and fermented. First of all, adjust the moisture and C/N ratio to an appropriate ratio by adding high-carbon and low-moisture auxiliary materials. Then, choose the fermentation method according to the scale of the pig farm and the site. Complete compost fermentation includes three stages: heating period, high temperature period, and cooling and decomposing period. Generally, in the simple case of pig farms, the high temperature period is mainly used to kill insect eggs through aerobic fermentation to achieve the purpose of harmlessness. Aerobic fermentation requires continuous turning of the pile, and pig farms with conditions can use ventilation equipment. This process usually takes 20 days. The aging time can be long or short, during which the piles are turned once a week. However, the aging time should not be too long, as microorganisms will consume nutrients.
If commercial organic fertilizers are produced, nutrients and water need to be adjusted to meet industry standards. If it is difficult to meet the standard with pure pig manure as raw material, it is generally necessary to add some additional raw and auxiliary materials, such as charcoal ash. Or add different proportions of nitrogen, phosphorus and potassium after fermentation and stir. It is understood that functional bacteria can also be added to continue fermentation to make various functional organic fertilizers. Biogas residues in the middle and lower layers of biogas digesters can also be used as raw materials for organic fertilizers, but the disadvantages are that there is a lot of nitrogen volatilization loss and high water content.
Equipment investment from hundreds of thousands to tens of thousands:
For small-scale pig farms, a certain area of ​​dung storage can be composted. There are also small-scale fermentation equipment for small-scale pig farms, but the cost is relatively high, and it is generally not recommended. Large-scale pig farms require larger sites and equipment to produce organic fertilizers.
Stack composting is a relatively common method. Raw materials are stacked into stacks, ventilation pipes are buried underground, and intermittent air blasts are used to supply oxygen, and the piles are turned once a day. At present, the fermentation site is 3,200 square meters, the warehouse is 1,000 square meters, and there are 12 composting lines, with a designed annual output of 10,000 tons of organic fertilizer. The total investment is more than 3 million including infrastructure, compost turning machines, crushing, sieving, packaging equipment, trucks and forklifts. Producing 10,000 tons of organic fertilizer requires about 20,000 tons of composting raw materials, removing 5,000 tons of auxiliary materials, and processing about 15,000 tons of pig manure. Based on this estimate, the daily processing capacity is about 55 tons.
On the basis of strip-stack composting, trough composting is developed, which has a higher degree of automation. After feeding from one end of the tank, the compost turner moves forward 3-4 meters every day. After 20 days, the fermented organic fertilizer is discharged from the other end. The depth and width of the organic fertilizer equipment tank should be designed according to the model of the compost turner, and one compost turner can be shared by multiple tanks.
The tower fermentation method uses the top to lift the feed, turn it in the tower, and quickly ferment with oxygen. It has the advantages of small footprint, closed and tasteless, short fermentation time, etc., but the equipment cost is high, the power consumption is large during operation, and the operating cost is relatively high.