What is Anaerobic Digestion?

Anaerobic digestion is a biological process where the methane released by the synergistic actions between bacteria and archaic are contained and used to create energy. Anaerobic digestion uses biomass such as manure as a feedstock. This process takes place under no oxygen present conditions. The manure or waste is contained and broken down using bacteria and water. This process releases methane as well as CO₂ in the tank, and it is taken into another tank where they must be separated. This makes anaerobic digestion a form of capturing methane and CO₂ that were about to be released to the earth’s atmosphere, and both gases are greenhouse type gasses.

The process begins at the molecular level, where hydrolysis converts a wide range of solid organic materials into sugars and amino acids.  Secondly a fermentation of these materials produces volatile fatty acids forming hydrogen, carbon dioxide, and acetate through acidogenesis. The final step, methanogenesis, is the one that produces biogas. This biogas is typically a mixture of 55-70 % methane, 25%-35% carbon dioxide, and trace elements of nitrogen and hydrogen sulfide, the percents varies from the manure source (i.e. cow, swine, etc.).  The ultimate yield of biogas depends on the composition and biodegradability of the biomass but its rate of production will depend on the population of microorganisms, their growth conditions and the temperature of the fermentation.

Utilizing the methane in this manner also aids in odor control and prevents the methane from seeping dangerously into the atmosphere, thereby rising levels of greenhouse gases and smog.

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