Anaerobic digestion

Biogas is formed by the process known as anaerobic digestion which basically means decomposition in the absence of oxygen. Anaerobic digestion occurs naturally wherever high concentrations of wet organic matter accumulate in the absence of dissolved oxygen. Under these conditions several types of bacteria work together to break down organic matter releasing gas which can then be stored and used as energy.

Bacteria

The bacteria thrive on organic mater and break down proteins, carbohydrates, cellulose and fats into low molecular compounds producing organic acids, carbon dioxide, hydrogen sulphide and ammonia. Further bacteria cultures process this mixture into carbon dioxide, alkaline water and methane - the valuable component of biogas. The whole process takes place inside a biogas fermenter, as pictured.

Substrates

Although there are several variations possible, the biogas systems all work in the same way. Substrate inputs like slurry, dry manure from cattle, pigs and poultry, raw materials such as corn or grass, organic waste including fats, vegetables and catering waste enter the fermenter where it is mixed, heated and agitated. In the proposed plant, rest materials from the bio oil production, bio diesel production and bio ethanol production enter the fermenter. Methane bacteria decompose the organic compounds and produce biogas and the processed digestate is separated for use as a natural fertiliser.

CHP

The biogas is then piped to a Combined Heat and Power (CHP) unit comprising a combustion engine and electrical generator where it is converted into heat and electricity. The heat and power can be used for the production of bio oil, bio diesel and bio ethanol.

Proven technology

In recent years, biogas production has become a completely new market in Germany and Denmark. The market in other European countries is still starting up. Biogas production is considered to be a proven technology.

Example of an installation

In one of our projects the biogas installation was presented as follows.  

Contact

For further information, please contact:

Ing. R.J.A. Korten MSc

T  +31 (0)6 109 25 309

F  +31 (0) 317 491 473

E  r.korten@dlvplant.nl