As mentioned, the composting process is based on the activity of microorganisms that live in the environment, since they are responsible for the decomposition of organic matter. So that these microorganisms can live and develop the decomposing activity, optimal conditions of temperature, humidity and oxygenation are needed.
There are many and very complex factors involved in the biological composting process, being in turn influenced by environmental conditions, type of waste to be treated and the type of composting technique used. The most important factors are:
- Temperature. Temperatures in the range 35-55 ° C are considered optimal to achieve the elimination of pathogens, parasites and weed seeds. At very high temperatures, many interesting microorganisms for the process die and others do not act when they are sporated.
- Humidity. In the composting process it is important that the humidity reaches optimum levels of 40-60%. If the moisture content is higher, the water will occupy all the pores and therefore the process would become anaerobic, that is, a rot of organic matter would occur. If the humidity is excessively low, the activity of the microorganisms is decreased and the process is slower. The moisture content will depend on the raw materials used. For fibrous materials or thick forest residues the maximum permissible humidity is 75-85% while for fresh plant material, it ranges between 50-60%.
- pH It influences the process due to its action on microorganisms. In general, fungi tolerate a pH range between 5-8, while bacteria have a lower tolerance capacity (pH = 6-7.5)
- Oxygen. Composting is an aerobic process, so the presence of oxygen is essential. The oxygen concentration will depend on the type of material, texture, humidity, turning frequency and the presence or absence of forced aeration.
- Balanced C / N ratio. Carbon and nitrogen are the two basic constituents of organic matter. Therefore, to obtain a good quality compost it is important that there is a balanced relationship between both elements. Theoretically, a C / N ratio of 25-35 is adequate, but this will vary depending on the raw materials that make up the compost. If the C / N ratio is very high, the biological activity decreases. A very low C / N ratio does not affect the composting process, losing excess nitrogen in the form of ammonia. It is important to make a proper mixture of the different residues with different C / N ratios to obtain a balanced compost. Organic materials rich in carbon and poor in nitrogen are straw, dry hay, leaves, branches, peat and sawdust. The poor in carbon and rich in nitrogen are young vegetables, animal waste and slaughterhouse waste.
- Microbial population Composting is an aerobic process of decomposition of organic matter, carried out by a wide range of populations of bacteria, fungi and actinomycetes.
