What is the working principle of the organic fertilizer production line?

When it comes to organic fertilizer, the first thing that comes to mind is fermented pure chicken manure and sheep manure. In fact, now the machinery is specialized in processing livestock and poultry manure into organic fertilizer granules for sale. In this process, an organic fertilizer production line is needed, so what is its working principle?
The processing of organic fertilizer is mainly the collection of raw materials, and then the raw materials are proportioned according to the required formula, the moisture content of the raw materials, the carbon-nitrogen ratio of the raw materials are adjusted, and fermentation begins.