Bio-digestion is the degradation of organic substances carried out by micro-organisms in anaerobic conditions - that is without oxygen -. It is called anaerobic digestion and it is an alternative process to composting, which, on the contrary, works in an aerobic environment.

Anaerobic digestion occurs in digesters ( reactors ) designed to avoid contact between oxygen and biomass, therefore maintaining a constant temperature. At the end of the process, part of the organic substance is transformed into a “biogas”, which mainly consists of methane and anhydrous carbon.

Anaerobic digestion can be carried out in wet and dry conditions. The first refers to a mixture of materials with a minimum content of solids of 30 %, while in the second the content of solids is a minimum of 15%.

Conventionally, in relation to the type of bacteria used, there are two different ranges of temperature in which the anaerobic digestion is carried out:

- with “mesophilic” bacteria the process is carried out at a temperature of between 20-45 °C, with an optimal range of 37°-41°C,
- with “thermophilic” bacteria the optimal operating conditions entail a range of a temperature of between 50°-52°C, with a temperature that can also be relatively high and exceed 70°C.

In recent years, a high request of anaerobic plants has been highlighted, since current knowledge, supported by innovative technology, is able to satisfy the demands of potential buyers fully respecting the environmental requirements established by the European Community.

Energen designs and supplies “ready to use” anaerobic plants.