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3A process

Three steps to sustainable recycling of biogenic waste





The bio-gas production using the 3A process in the PÖTTINGER fermenter is based on the discontinuous dry fermentation of biogenic waste (organic waste and municipal waste as well as organic residues) whilst excluding oxygen.

This produces CO2-neutral methane. This in turn can be converted into green electricity and heat or into natural gas quality bio-gas or can be used as fuel (LNG) for commercial vehicles. This can save fossil fuels.


The process also accelerates the composting. Instead of going through the principal rotting phase, the organic waste is filled into the fermenter boxes with a working volume of ca. 45 m³. Then bio-gas is created in a three-stage process.

  • The 1st phase is aerobic and so the material in the fermenter is aerated.
  • In the 2nd phase, the aeration is stopped and the anaerobic process starts. To support this, a percolate is sprayed onto the material and the temperature in the fermenter box is controlled. The bio-gas production starts and takes between 3 to 4 weeks.
  • If the material has been fermented, the fermenter box is aerated again in the 3rd phase and the anaerobic process is stopped.

The remaining material is further processed into compost in a post-rotting process and can be used as humus fertiliser.

In contrast to simple disposal and combustion of organic residues, the recycling in a PÖTTINGER fermentation system completes the material cycle both in economical and ecological terms.