HUBER supplies machines for faecal sludge treatment on the Faroe Islands

The Faroe Islands are probably known mainly to nature lovers with a penchant for rather unusual destinations. So it was initially something interesting and different for a change when HUBER received an enquiry in mid-2017 for a faecal sludge treatment plant for predominantly domestic sludge. At least 10,000 t of sludge were to be received annually, screened and then dewatered to ≥ 35 % dry residue (DR).

Three HUBER Screw Press Q-PRESS® units for sludge dewatering
Three HUBER Screw Press Q-PRESS® units for sludge dewatering

Transport with suction and tanker vehicles

What makes this project special is first and foremost the input DR: The sludge is collected island-wide with suction and tanker vehicles of the Simon Moos company. These special vehicles have several tanks and, with the addition of polymer, can thicken the sludge to 9 – 11 % DR, or even more if the sludge is left standing for a longer time. This reduces the unnecessary transport of water over the sometimes long distances on the island.

The task

Screening of flowable sludge is a standard task for HUBER and has been tried and tested many times, but the pre-thickened material is almost solid and cannot be screened in this condition. However, the challenge was to treat sludge from 2 % to about 11 % DR equally.

HUBER Reception Bunker, Wash Drum and Screw Press

After considering various options, the first budget offer was for a HUBER Reception Bunker RoSF7 with re-dilution of the sludge as required, followed by a HUBER Wash Drum RoSF9 for sludge screening. Afterwards, the sludge was to be collected in a buffer and from there pumped to the proven HUBER Screw Press Q-PRESS® for dewatering.

Receiving, screening and dewatering with HUBER Reception Bunker RoSF7, Wash Drum RoSF9 and Wash Press WAP®
Receiving, screening and dewatering with HUBER Reception Bunker RoSF7, Wash Drum RoSF9 and Wash Press WAP®

Samples, analyses, trials

As a next step, a sludge sample was analysed in the HUBER laboratory in autumn 2017 and dewatering tests were carried out – with promising results. The interest of the operator IRF in Leirvik was now high and it was only a matter of evaluating the "unknown" with the thickened sludge. During a visit to the Faroe Islands in the summer of 2018, the delivered sludge was inspected, simple tests for re-dilution were carried out and the operator's expectations and requirements were discussed. IRF is the central supplier and disposal contractor for water, wastewater, waste and energy for most of the Faroe Islands.

Based on the findings and agreements of the visit, it was now possible to render the offer more precisely in cooperation with a Danish plant constructor and to start with the detailed planning of process engineering and construction.

The machines in the order placed with HUBER

The order to HUBER was placed in December 2020 and included the following components for delivery in December 2021:

  • 1x HUBER Sludge Reception Bunker RoSF7 with integrated unit for re-dilution
  • 1x HUBER Wash Drum RoSF9 for sludge screening
  • 1x HUBER Wash Press WAP® for dewatering of screenings
  • 3x thin sludge pump for feeding the screw presses
  • 3x flocculant conditioning plant
  • 3x HUBER Screw Press Q-PRESS®

Agreed guarantee values achieved

After completion of the building and process technology, the wet commissioning was successfully completed in December 2022 against a spectacular natural backdrop. The agreed guarantee values of 35 % DR in the dewatered sludge were achieved and this with minimal polymer use. To sum up: IRF receives future-oriented technology for the treatment of faecal sludge and HUBER adds a reference to its project portfolio in the midst of impressive surroundings.

Willi Kölbl