BIOFOS - Lynetten: Climate-positive efficiency improvement of biogas production

BIOFOS has renewed and renovated its biogas production facilities at the Lynetten water treatment plant over a number of years. Aquagain – Folding Smed A/S has along the whole way been involved in various mechanical engineering contract work, which have now been finally completed.
Aquagain's task has been to help BIOFOS towards its goal of becoming "climate-positive" by 2025 by reducing CO₂ and nitrogen emissions to the Sound and utilising the resources in the wastewater at Lynetten.

New digester tanks with particularly efficient mixing
We have supplied the entire machinery for the complete digester plant, i.e. 2 new digester tanks and renovation of 3 existing digester tanks.

In the 2 new digester tanks, we have chosen Draft Tube mixers supplied by Hermann Träxler; in addition to efficient mixing, they contribute to effective foam attenuation. The new digester tanks are relatively flat-bottomed and thus provide an increased sludge volume.

Plant in operation throughout the project
In connection with the project, the pump cellar has been expanded and at the same time existing pipe installations have been replaced and reduced in number. This has been a very lengthy project, as we have had to keep the plant in operation throughout the conversion and thus handle the volume of sludge added.

Divers in the digester tanks
In the existing digester tanks, the top mixer has been replaced - a somewhat special task, since 2 of the 3 mixer shafts were broken. Dismantling had to be done using crew baskets and specially trained divers who had to "swim" out to them to be able to hook them.

Such a lengthy project requires a close and constructive dialogue with the client and its operational staff, which our installation team handled to the great satisfaction of all parties.
 
Aquagain has thus contributed with solutions and know-how that ensure BIOFOS the best possible starting point for reducing the plant's climate impact.

Technical challenges
It is clear that when you work on such a large project over several years, you will run into some exciting challenges that require tremendous professionalism, creativity and strong technical solutions.

Including a small selection of exciting challenges concerning the project:

• Installation of sand removal systems in existing digesters
  It was an interesting challenge to get the up to 14m long sand removal pipes towed into the digester tank and then installed along the conical bottom.
• Dismantling of the old approx. 25m long agitators
   - one of which had a broken shaft
• Installation of approx. 20m long DN300 pipes in stairwell
• Various modifications of pipes carried out on-site
   - including modification of trace and pipe sizes

We are happy and proud to have been part of BIOFOS's journey towards larger and more efficient biogas production and look forward to continuing the excellent collaboration on new projects.