The oxygen supply is one of the basic conditions for aerobic fermentation production.

The main functions of fertilizer compost are:

1. Provide oxygen to accelerate the fermentation process of microorganisms.

2. Adjust the reactor temperature.

3. Dry the stack.

The number of turns is small, and the ventilation rate is not enough to provide sufficient oxygen for microorganisms, which affects the rise of fermentation temperature; The more times the compost is turned over, the heat of the compost pile may be lost, and the degree of harmless fermentation will be affected. Usually, the pile is turned 2-3 times during fermentation according to the situation.

The content of organic matter affects the stack temperature and ventilation 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 fermentation, and the compost pile is difficult to reach the high temperature stage, affecting the health and harmless effect of fermentation. Moreover, the low content of organic matter 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 is required, which will cause practical difficulties for the oxygen supply of the pile, and may cause partial anaerobic conditions due to insufficient oxygen supply. The suitable organic content is 20-80%.

3.The optimal C/N ratio is 25:1

In fermentation, organic C is mainly used as the energy material of microorganisms. Most organic C is oxidized and decomposed into CO2 and volatilized during microbial metabolism, while some C forms the cell material of microorganisms themselves. Nitrogen is mainly consumed in protoplast synthesis, and the most appropriate C/N ratio is between 4 and 30 in terms of microbial nutrition needs. When the C/N ratio of organic matter is about 10, the decomposition rate of organic matter by microorganisms is the highest.

With the increase of C/N ratio, the fermentation time was relatively prolonged. When the C/N ratio of raw materials is 20, 30 to 50, 78, the corresponding fermentation time is about 9 to 12 days, 10 to 19 days, and 21 days, respectively, but when the C/N ratio is greater than 80:1, the fermentation is difficult.

The C/N ratio of each fermentation raw material is usually 300~1000 sawdust, 70~100 straw, 50~80 raw material, 6~10 human dung, 8~26 cow dung, 7~15 pig dung, 5~10 chicken dung, and 8~15 sewage sludge.

After composting, the C/N ratio will be significantly lower than that before composting, usually between 10 and 20:1. This kind of C/N ratio of composting fermentation has better fertilizer efficiency for agricultural use.

4. Whether the water content is appropriate directly affects the fermentation speed and maturity. For sludge fermentation, the appropriate moisture content of the compost is 55-65%. In practical operation, the simple and convenient determination method is: hold the material tightly with your hand to form a mass, and there are water traces, but the water does not drip out. The most suitable moisture content for raw material fermentation is 55%.

5. Granularity

The oxygen required for fermentation is supplied through the pores of fermentation raw materials. Porosity and pore size depend on particle size and structural strength. For example, paper, animals and plants, fiber fabrics, etc., when pressed with water, the density will increase, and the pores between particles will be greatly reduced, which is not conducive to ventilation and oxygen supply. The appropriate particle size is generally 12-60mm

6. pH microorganisms can reproduce in a large pH range, and the appropriate pH is 6-8.5. It is usually not necessary to adjust the pH value during fermentation.