Organic fertilizer production line processing organic fertilizer production process

1. Organic fertilizer production principle and microbiological process Basic principles
   Aerobic fermentation is under aerobic conditions, aerobic microorganisms decompose and oxidize a part of organic matter into simple inorganic matter through their own catabolism and anabolism process, from which they obtain the energy required for microbial metabolism, and at the same time convert part of the organic matter into synthetic New cellular material, the process by which microorganisms grow and multiply to produce more organisms. The result of fermentation is that the organic matter in the waste is transformed into humus with a higher degree of stabilization.
2. Microbiological process
   The microbiological process of aerobic fermentation can be roughly divided into three stages, each stage has its own unique microbial groups:
   1) Heat production stage (medium temperature stage, heating stage)
   In the initial stage of fermentation (usually 1-3 days), mesophilic microorganisms in the compost heap use soluble and easily degradable organic matter as a source of nutrition and energy, proliferate rapidly, and release heat energy, which makes the temperature of the compost heap continuously rise. At this stage, the temperature ranges from room temperature to 45°C, and the microorganisms are mainly mesophilic and aerobic, usually some non-spore-forming bacteria. There are many types of microorganisms, mainly bacteria, fungi and actinomycetes. Among them, bacteria mainly use water-soluble monosaccharides, etc., and actinomycetes and fungi have special functions for decomposing cellulose and hemicellulose substances.
   2) High temperature stage
   When the temperature of the compost heap rises above 45°C, it enters the high temperature stage. Usually, starting from accumulation fermentation, it only takes 2-3 days for the temperature of the compost pile to rise rapidly to 55°C, and the pile temperature can reach a high value within 1 week (the high temperature can reach 80°C). Mesophilic microorganisms are suppressed and thermophilic microorganisms gradually take their place. In addition to the residual and newly formed soluble organic matter in the previous stage continued to decompose and transform, complex organic matter such as hemicellulose, cellulose, and protein also began to decompose strongly. It is mainly thermophilic fungi and actinomycetes that are active at around 50°C; when the temperature rises to 60°C, the fungi almost completely stop their activities, and thermophilic actinomycetes and bacteria are active; when the temperature rises above 70°C, large Most thermophilic microorganisms are no longer suitable, and a large number of microorganisms die or enter a dormant state. At this time, the heat generated decreases and the stack temperature drops automatically. When the pile temperature drops below 70°C, the dormant thermophilic microorganisms will reactivate and continue to decompose the refractory organic matter, and the heat will increase again. The pile temperature will be in a naturally regulated and long-lasting high temperature period.
   High temperature plays an important role in the rapid fermentation of fermentation. During this stage, the formation of humus begins in the fermentation process, and black substances that can dissolve in weak alkali begin to appear. The C/N ratio decreased significantly, and the height of the compost heap decreased accordingly. Pathogens in organic waste can be effectively killed by high temperature. According to my country’s high-temperature fermentation hygiene standard (GB7959-87), the highest fermentation temperature is required to be above 50-55°C for 5-7 days.
   3) Decomposition stage
   At the end of the high temperature stage, only part of the organic matter that is difficult to decompose and the newly formed humus remain. At this time, the activity of microorganisms decreases, the calorific value decreases, and the temperature drops. At this time, mesophilic microorganisms dominate again, further decomposing the residual organic matter that is difficult to decompose, and the humus continues to increase and tends to be stabilized. At this time, the fermentation enters the decomposing stage.
   After cooling down, the oxygen demand is greatly reduced, the gaps in the compost heap are enlarged, and the oxygen diffusion capacity is enhanced. At this time, natural ventilation is only required. The common after-ripening treatment in forced-air fermentation is to turn the aerated pile once, then stop the aeration and let it rot. It also acts as a nitrogen retainer.

Fermentation procedure and process of organic fertilizer
Fermentation procedure:

Pretreatment of raw materials: including sorting, crushing, adjustment of moisture content and carbon-nitrogen ratio.

Fermentation of raw materials: the cycle generally takes 15-20 days.
1) Stage 1: Refers to the microbial metabolic process in two stages of mesophilic fermentation and high temperature. It refers to the entire process starting from the initial stage of fermentation, going through medium temperature, high temperature, and then reaching the temperature and starting to drop. It usually takes 10-12 days.
2) The first stage: After the material is fermented in the first stage, there are still some organic matter that is easy to decompose and a large amount of refractory organic matter, which needs to continue to ferment to make it decompose. At this time, the temperature continues to drop, and when the temperature is stable at about 35-40°C, it will reach maturity, which generally takes 5-10 days.

Post-processing: post-processing includes removal of impurities and necessary crushing.
Process flow

Stacking technology
The ground is compacted before the pile, and then the fermented materials such as manure, peat, and Le Beifeng second desiccant are mixed in proportion to make the pile.

Stirring, stacking and stacking fermentation process
The materials are stacked in stacks and can be arranged into multiple parallel stacks. The section shape of the stacks is usually triangular or trapezoidal, with a height of 1.5-2.0m and a width of 4-6m. The moisture content of the pile after mixing is 55-65%.
The fermentation process is as follows:
Fermentation raw materials—pretreatment—mixing—fermentation—remodulation—granulation—packaging—delivery
In the pretreatment, sometimes it is necessary to crush the raw materials to adjust the particle size of the raw materials. The suitable particle size range is 12-60mm. Crushing and sieving can increase the surface area of raw materials, facilitate the reproduction of microorganisms, and increase the fermentation speed. After stacking, it can be turned every 4-7 days, and it can be stopped after 1 month to let it mature naturally.

Influencing factors of fermentation and their control

Turn over
Oxygen supply by turning piles is one of the basic conditions for aerobic fermentation production. The main functions of turning over are: ①providing oxygen to accelerate the fermentation process of microorganisms; ②adjusting the pile temperature; ③drying the pile.
If the number of turnings is small, the ventilation volume is not enough to provide sufficient oxygen for the microorganisms, which will affect the rise of the fermentation temperature; if the number of turnings is too high, the heat of the compost heap may be lost, affecting the degree of harmlessness of fermentation. Usually according to the situation, the pile is turned 2-3 times during fermentation.

Content of organic matter
The content of organic matter affects the stockpiling temperature and ventilation and oxygen supply. The content of organic matter is too low, the heat generated by decomposition is not enough to promote and maintain the proliferation of thermophilic bacteria in the fermentation, and it is difficult for the compost heap to reach the high temperature stage, which affects the hygienic and harmless effect of fermentation. Moreover, due to the low content of organic matter, it will affect the fertilizer efficiency and use value of fermented products.
If the content of organic matter is too high, a large amount of oxygen supply will be required, which will cause practical difficulties in turning over the pile for oxygen supply, and may cause partial anaerobic conditions due to insufficient oxygen supply. The suitable organic matter content is 20-80%

C/N ratio
Appropriate 25:1
In the fermentation process, organic C is mainly used as an energy source for microorganisms. Most of the organic C is oxidized and decomposed into CO2 and volatilized in the process of microbial metabolism, and part of C constitutes the cell matter of microorganisms themselves. Nitrogen is mainly consumed in the synthesis of protoplasts. In terms of the nutritional needs of microorganisms, the appropriate C/N ratio is between 4 and 30. When the C/N ratio of organic matter is around 10, the organic matter is decomposed by microorganisms faster.
With the increase of C/N ratio, the fermentation time is relatively prolonged. When the C/N ratio of the raw material is 20, 30-50, 78, the corresponding fermentation time is about 9-12 days, 10-19 days, and 21 days, but when the C/N ratio is greater than 80 When : 1, fermentation is just difficult to carry out.
The C/N ratio of each fermentation raw material is usually: sawdust 300-1000, straw 70-100, raw material 50-80, human manure 6-10, cow manure 8-26, pig manure 7-15, chicken manure 5-10 , Sewage sludge 8-15.
After composting, the C/N ratio will be significantly lower than that before composting, usually at 10-20:1. This kind of C/N ratio for decomposing and fermenting has better fertilizer efficiency in agriculture.

Moisture
Whether the moisture is suitable directly affects the fermentation speed and maturity degree of fermentation. For sludge fermentation, the appropriate moisture content of the pile is 55-65%. In actual operation, the simple method of determination is as follows: hold the material tightly with your hand to form a ball, and there will be water marks, but it is better that the water does not drip out. The suitable moisture for raw material fermentation is 55%.

Granularity
The oxygen required for fermentation is supplied through the pores of the fermentation raw material particles. The porosity and pore size depend on the particle size and structural strength. Like paper, animals and plants, and fiber fabrics, the density will increase when exposed to water and pressure, and the pores between particles will be greatly reduced, which is not conducive to ventilation and oxygen supply. The suitable particle size is generally 12-60mm.

pH
Microorganisms can reproduce in a larger pH range, and the suitable pH is 6-8.5. There is usually no need to adjust pH during fermentation.

Judgment indicators

Decomposition degree: the degree of maturity of fermentation
1) Appearance change: The intuitive qualitative judgment standard is that the fermentation is no longer violently decomposed, and the temperature of the finished product is low; the appearance is tea-brown or black; the structure is loose; and there is no foul smell.
2) Temperature change: Usually, the temperature of the compost heap will gradually drop after passing through the high temperature stage. When the fermentation reaches maturity, the pile temperature will be lower than 40°C.

Chemical index
1) Changes in organic matter and volatile solid content: With the progress of fermentation, the organic matter and volatile solid content of fermentation showed a continuous downward trend and reached a basic stability. When it reaches maturity, it can be reduced by 15-30%. However, this trend is greatly influenced by the source of raw materials. It is not sufficient to use it only to measure whether the fermentation is decomposed.
2) Changes in nitrogen, C/N ratio and inorganic nitrogen form: During the fermentation process, part of the organic carbon will be oxidized to CO2 volatilization loss, and the quality of the compost heap will decrease. Since the loss of nitrogen (mainly in the ammonification stage of organic nitrogen, a small amount of ammonia nitrogen will be volatilized and lost) is much lower than the loss of organic carbon, therefore, after fermentation and maturity, the total nitrogen content in fermentation tends to increase, while C/N ratio continued to decrease until it stabilized. Some studies indicate that the compost heap will reach a plateau when the C/N ratio of the compost decreases from 25 to 35:1 to below 20:1.