Anaerobic digestion is the processes where biodegradable material is broken down in the absence of oxygen. This means the anaerobe organisms do not require oxygen in order to live and thrive.
This process occurs in a biogas digester, which is part of a biogas generator plant. This breakdown of organic biodegradable material produces among other things biogas, which can then be used as a cheap energy source for a biogas generator.
What is considered organic material is anything that is plant based or which comes from animals. Examples of biodegradable organic material would be left over food scraps, grass, leaves, tree bark, fruit and vegetable peels, animal manure, and sewage sludge.
Another reason for anaerobic digestion is to process or manage biodegradable waste and sewage, especially useful for industrial purposes, and for reducing the release of landfill gas into the atmosphere. Because of the production of biogas, the anaerobic digestion process is seen as a source of renewable energy, which is used to produce electricity through power generators, and also as fuel to power gas engines.
The biogas can also be upgraded to natural gas quality, thus making it an even cleaner biofuel to be used on motor vehicles, and other forms of transportation that use gas engines powered through natural gas.
Another product of this process is the production of fertilizer, as the nutrient rich bio product, called digestate is very good in fertilizing agricultural land.
Fermentation as used in an industrial and domestic/home process uses anaerobic digestion to produce food and drink products. This is achieved by anaerobic organisms/bacteria breaking down the organic or biodegradable matter in a metabolic process. For more information on how this process happens, check out the video below.