"In addition to the main components methane and carbon dioxide, biogas also contains traces of hydrogen sulphide. The latter must be removed from the gas before the biogas is converted into electricity in the combined heat and power plant in order to ensure the longevity of the unit. There are various technological approaches on the market for this with different levels of efficiency," reports Dr Anja Schreiber.

In cooperation with the Thuringian companies UGN-Umwelttechnik GmbH, BTN Biotechnologie Nordhausen GmbH, R&G EMSR- Technik GmbH and supported by the network partner Energieversorgung Nordhausen - Biomethan GmbH, the bioprocess engineering team led by Prof Uta Breuer and Dr Anja Schreiber is now developing a completely new type of process.

"In a previous project, we were already able to demonstrate the high purification performance of the sulphur bacteria Beggiatoa alba and Thiotrix nivea, which are found in aquatic systems. The innovative idea is now a modular three-stage desulphurisation process that combines the advantages of the existing desulphurisation systems available on the market. While in the first stage the new sulphur bacteria take over the main performance, in the second stage they are supported by the naturally occurring sulphur bacteria in liquid manure. The last step is our safety step. Here, iron-doped cellulose pellets guarantee 100 % gas purification," explains Prof Dr Uta Breuer.

New to the team are the two scientists M.Eng. Lynn Vincent and Maren Podewski, who, in addition to supervising and optimising the pilot plant, are using molecular biological methods to test the efficiency of the sulphur bacteria used.

Following the successful realisation of the 30-month project, the laboratory plant is to be scaled up to a pilot plant in a continuing research project. This will then be integrated into the gas flow of an agricultural biogas plant and tested in practical operation.

PM 5/2020