Operating principle

In process engineering terms, a distinction can be made between single-stage and two-stage plants. In single-stage plants, all four phases of anaerobic digestion take place in one tank. This inevitably means reconciling the different environmental requirements of the various microorganisms. As a result, the digestion processes take quite a long time, so single-stage plants require a larger digestion volume. The temperature and pH must be adjusted to suit the methane-producing bacteria, as these are the most sensitive and reproduce the slowest.

Physically separating hydrolysis/acidification from acetic acid formation and methane formation allows more favourable conditions to be created for the microorganisms. This is known as a two-stage process.

For this reason, Archea Biogastechnologie GmbH has designed two different plant types. This plant type is ideal for plants that predominantly use liquid materials with a low energy density and therefore require a large volume. The Standard Plus plant type consists of a single-stage circular tank (Standard plant type) and an upstream hydrolysis stage, in which the first two stages of anaerobic degradation take place separately from the conventional process. This significantly accelerates biological processing, and the digestion volume can be considerably reduced compared with single-stage plants.

This plant type is primarily used for plants that use a high proportion of energy crops and therefore place significantly greater demands on process biology.

This plant type is suitable for all conventional substrates, as well as substrates with a high dry matter content, such as large quantities of grass silage and landscape maintenance material. The hydrolysis stage increases gas yields, reducing substrate requirements by up to 15%!