1. There are four key biological/ chemical reaction stages of anaerobic digestion:
2. Almost any organic matter can be digested anaerobically. Not all will produce enough biogas to be viable though.
3. Anaerobic digestion occurs in nature at all temperatures, but below 10 degrees centigrade the rate of biogas production is so slow that running a biogas process is usually considered not viable, for any form of biogas generation system.
4. There are two temperature ranges over which the many micro-organisms which produce biogas work most efficiently. These are known as the:
Temperature ranges, with the optimum temperature usually considered to be at the top of the range.
5. The process is truly ancient:
- Fermentation for the production of alcohol was known to the Ancient Egyptians and is recorded as far back as 2,000 BC.
- The methane producing stage of anaerobic digestion is performed by a type of micro-organism known as archaea. It's not a bacteria. In fact in comes from a distinctly different branch of the phylogenetic tree of life to bacteria.