1.3. Fermentation Slurry
All feed materials consist of organic solids, inorganic solids and water. Biogas is formed by digestion of the organic
substances. The inorganic materials (minerals and metals) are unused and are unaffected by the digestion
process. Adding water or urine gives the substrate fluid properties. This is important for the operation of a biogas
plant [5]. It is easier for the methane bacteria to come into contact with feed material which is still fresh when
the slurry is liquid. This accelerates the digestion process. Regular stirring thus speeds up the gas production.
Slurry with a solids content of 5% - 10% is particularly well suited to the operation of continuous biogas plants
[4] [5].