The composting plant is located in the Tufo Colonoco area within the Municipality of Isernia and is equipped with a forced maturation system for organic material in a closed and spatially confined environment. Intensive tunnel composting allows for precise control and management of the key parameters of the process.
The selected plant configuration can be defined as a continuously aerated composting system, characterised by a dedicated air insufflation and extraction system that ensures the correct development of bio-oxidative processes.In practice, this process represents the reproduction, under controlled and accelerated conditions, of the natural degradation mechanisms of organic matter. It can be described as occurring in two main phases: accelerated bio-oxidation and maturation.
During the accelerated bio-oxidation phase, the biomass contains a high amount of putrescible organic matter, the degradation of which requires a significant consumption of oxygen. The initial bio-oxidative processes develop rapidly, producing heat and carbon dioxide and expelling excess liquids. The most readily degradable organic fractions — such as sugars, amino acids and organic acids — therefore undergo rapid digestion through the action of thermophilic bacteria (schizomycetes), which cause the temperature to rise and, within a few days, reach and exceed 70°C.
Once the most fermentable organic fraction has been degraded, most bacterial activity gradually diminishes and slower decomposition processes begin, driven by specific microorganisms responsible for humification. During this phase, the temperature decreases to values of approximately 45–55°C, the pH gradually lowers and stabilises close to neutral values, and moisture content drops to levels not exceeding 40%. This marks the development of the microaerobic maturation phase, during which the synthesis of more complex polymers leads to the formation of a substrate suitable for humus production.
The plant can be schematically divided into the following sections:
In the accelerated bio-oxidation section, the air required for the degradation of the organic material forming the compost matrix is injected through the perforated floor of the tunnel. The air passes through the material and is then extracted via the outlet duct of the tunnel, where it is recirculated. If necessary, it is mixed with fresh air to provide oxygenation and/or cooling before being reintroduced into the tunnel.
Once its treatment capacity has been exhausted, the process air is conveyed to the air treatment and deodorisation system, consisting of a scrubber and biofilter. When required, the process air can also be humidified through water spraying.