Odour-free start-up guaranteed for biogas plants

Acute odour nuisance caused by one specific plant led to a storm of protest in Denmark, which had a detrimental effect on public opinion about biogas plants. This resistance even resulted in the postponement and cancellation of new projects. A leading player in the Danish market realised that a comprehensive, lasting solution was required to tackle the problem vigorously and to re-establish a basis for such biogas plants with local residents.

In the past, the company had already invested in biofilters and bioscrubbers to tackle odour problems. However, these systems do not provide an adequate solution at the start-up of a biogas plant. During those first weeks, organic matter is pumped into the digesters, after which the bacteria slowly start doing their work and ensure a strong scented gas emission, influenced, among other things, by the presence of hydrogen sulphide (H2S). Because it takes a while for biofilters and scrubbers to run at full speed, they cannot address this odour problem.

Because of the urgency of the project, DESOTEC had to react quickly. The mobile installation was delivered in mid-April 2019 from the head office in Roeselare and was put into operation two weeks later. It has resulted in high customer satisfaction, which led the Danish company to apply this approach to the start-up of every new biogas plant. In addition, the company wants to carefully define all the odour sources of biogas plants at every (new) site in the future, and also treat them with activated carbon filtration.

At DESOTEC’s facilities, all used carbon is analysed so the right measures can be taken for handling and removing the saturated carbon out of the mobile filters. All molecules that were adsorbed on the activated carbon at the customers’ site, are desorbed inside DESOTEC’s reactivation furnaces. These contaminants are then fully destroyed, in accordance with National and European legislation, by an incineration and neutralisation setup. The entire installation and it's emissions are under continuous on-line monitoring, which guarantees that only harmless water vapour is seen exiting the chimney.