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Technology in Action
Case Study
Førde WWTP, Sunnfjord Municipality, Norway

The Førde WWTP is a Biological/Chemical Plant built in 2010, spread over 1,200 SQM and dimensioned for 28,000 PE (including future growth toward 2030). It receives +1,200,000 M3/Year of wastewater and produces +2,500 Tons/ Year of sludge. Their inlet wastewater concentration (in terms of BOD₅, COD, and ToT-P) is 2X to 3X that of the Norwegian national average. Regulatory compliance states it must achieve at least +70 % BOD₅ removal (and less than 25 mg/l), + 75% COD removal (and less than 125 mg/l) as well as +90% ToT-P removal. ​

This is not a unique challenge to Førde WWTP. Norsk Vann states that between 2021 to 2040 there are some 1,900 WWTPs in Norway that require extensive upgrades and/or expansions with a conservative total investment of 72 billion NOK. This investment estimate does not take into consideration the new wastewater regulatory framework which will take effect in 2024.  

From day 1, Førde WWTP was operating at max capacity where today it operates between 32,000 PE and 35,000 PE creating significant operating stress and compliance risk. In 2021, an expansion requirement was placed on the facility to expand operational capacity up to 45,000 PE, a 50% increase requiring a time-consuming and capital-intensive investment in a new facility expansion.

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Over the last two years, renasys has tested our R.660X Discovery Series, connecting into the Førde WWTP treatment process right after sand / fat traps and just before their bioreactors. 

Testing several 3D Filtration levels (specifically 40 and 20 microns), suspended solids removal rates (SSR%) were upwards of 94% with an average of +70% SSR. This has a direct impact on removing a significant percentage of COD, BOD₅, and ToT-P.


Installing the R.660X Discovery Series upstream of their bioreactor, more of the particulate organic matter is removed prior to the biological treatment. This reduces the organic loading of the bioreactor, enabling the use of a much smaller bioreactor while requiring significantly less energy for aeration.

The R.660X Discovery Series also proved to enable flexibility of outlet primary sludge (carbon) concentration (TS%) from 6% and up to 60% depending on what the carbon was to be used for (in terms of energy, bio-char, and/or fertilizers).

Next Steps

Given the successful commercial testing, renasys and Sunnfjord Municipality are now assessing a potential full-scale renasys carbon harvesting solution using a multistep Advanced Fine Filtration process going from 40 microns down to 10 microns.

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