The discovery of biogas dates back to two events in the 17th Century, when Plinius noted the appearance of lights from beneath swamps, and Van Helmont recorded that decaying organic matter produced an inflammable gas. By 1776, a man named Volta concluded that the amount of gas produced depended on the amount of decaying material in the ground, and that certain concentrations of the gas could form an explosive mixture with air. Another step forward was made in 1804– 1810 by Dalton, Henry, and Davy, who established the chemical composition of methane, showed that it could be produced from decaying cow manure, and confirmed that it was very similar to the marsh gas Volta described.
More advancements were made in the late 1800′s when Bechamp was able to identify the organism responsible for methanogenesis (producing methane) from ethanol. He also discovered that the “culture” the organism was from was mixed, because the fermentation products changed depending on the substrate. This was a huge discovery, because up until this time it had been assumed that the process was achieved by the work of a single species. In 1876, the stoichiometric conversion from acetate (found in sewage sludge) to methane and carbon dioxide was discovered. And finally, the first man-made gas was produced in 1884 by a French student named Gayon, who was able to generate methane by fermenting manure (thus showing that fermentation could be used to generate a source of fuel).
This process was used to light streets in Exeter, England in 1896, and methods of optimizing the gas production were studied and researched. This included using a two-stage process to separate the suspended material from the waste water (1904), the use of two distinct acetate-utilizing bacteria (1906), practical heating of the reactor in colder temperatures by using the gas produced to run a motor (1914– 1923), refinement of the understanding of the chemistry (stoichiometry of the reaction, energy production, and what happens to the nitrogen) of the process (1920– 1936), and the isolation of two of the methane-producing species: Methanosarcina barker and Methanobacterium formicicum (which are still being studied today) (1947).
These studies (and many more) have led to knowledge of the importance of things like seeding and pH control. These issues are still important today, and current reactors owe much of their efficiency to this early research.
(Paraphrased from this article)