Anaerobic digestion is a biological process making it possible to degrade organic matter by producing biogas which is a renewable energy source and a sludge used as fertilizer.
The production of biogas
is carried out in the environment in a natural way (e.g. gas of marshes
- vegetable and animal matter decomposition where the formation of
bubbles at water surface can be observed).
In the absence of oxygen (anaerobic digestion), the organic matter is degraded partially by the combined action of several types of micro-organisms. A succession of biological reactions (see diagram) led to the formation of biogas and sludge.
The bacteria which carry out these reactions exist in natural state in the liquid manure and the anaerobic ecosystems; it is not necessary to add more, they develop naturally in a medium without oxygen.