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Biogas production relies on anaerobic bacteria to transform manure and other organic material into biogas and liquid effluent. There are three stages to the process of biogas production.

  1. Liquefaction
    Liquefying bacteria convert insoluble, fibrous materials such as carbohydrates, fats, and proteins into soluble substances. Water, some fibrous material, and other inorganic material also can accumulate in the digester or pass through the digester unchanged. Undigested materials make up the low-odor, liquefied effluent.
  2. Acid Production
    Acid-forming bacteria convert the soluble organic matter into volatile acids--the organic acids that can cause odor production from stored liquid manure.
  3. Biogas Production
    Methane-forming bacteria convert those volatile acids into biogas--a gas composed of about 60 percent methane, 40 percent carbon dioxide, and trace amounts of water vapor, hydrogen sulfide, and ammonia. Not all volatile acids and soluble organic compounds are converted to biogas; some become part of the effluent.

Biogas Resources