Biogas Production


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•  Biogas is produced by bacteria and archaeans from organic matter in fermenters

Biogas is a clean and renewable fuel source produced by the breakdown of organic matter by particular microorganisms

  • Biogas is primarily composed of methane, carbon dioxide and water vapour
  • Biogas can be produced from a variety of sources of biomass – including manure, sewage, agricultural waste or food scraps

The production of biogas involves two groups of microorganisms – eubacteria and archaeans (methanogens)

  • Bacteria first convert the organic material into organic acids and alcohol
  • Other bacteria convert these products into acetate, carbon dioxide and hydrogen gas
  • Archaeans then create methane, either via breakdown of acetate or via a reaction between carbon dioxide and hydrogen gas 

The production of biogas can occur in small-scale fermenters under anaerobic conditions

  • The fermenter needs to be maintained at a neutral pH (~ 7) and constant temperature (~ 35ºC) to maximise yield

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•  Production of biogas in a small-scale fermenter

Small-scale biogas fermenters are air-tight containers that anaerobically break down kitchen and garden wastes to produce biogas

  • The fermentation process produces a digested slurry (digestate), which can be used as a fertilizer
  • The biogas forms within the slurry and collects at the top of the chamber, where it can be transported for use via an outlet

The main design elements of a biogas fermenters are an air-tight chamber, an inlet and a vessel for biogas collection

  • A small-scale fermenter can also be directly linked to toilets for the additional treatment of human excreta
  • Small-scale biogas fermenters are typically used by households or communities in rural areas as a supplementary fuel source

Overview of Biogas Production