Facts & Figures

 ClientWater Authority Noorderzijlvest
 LocationGroningen, The Netherlands
 Operation Start2014
 Project TypeBrownfield
 Process ConfigurationPre-treatment + Nereda
 Nereda Design Capacity:
  • Dry Weather Flow20 MLD
  • Peak Flow4,200 m3/h
  • PE91,583 PE (PE = 60 gBOD/d)
 In the Media:Dutchwatersector.nl
 Water 21


Garmerwolde WWTP is located near Groningen in the North of the Netherlands.

The Challenge

The treatment plant at Garmerwolde processes wastewater from the surrounding area and serves approximately 350,000 people. The existing plant, which consisted of a two-stage activated sludge system, did not have sufficient capacity to meet the growing needs of the region and was not able to meet the required effluent standard. This resulted in a plant upgrade for the site, with new technology needed to increase efficiency and output.

Nereda WWTP Garmerwolde, the Netherlands

The Solution

The client Water Authority Noorderzijlvest selected Nereda as the best wastewater purification solution to run alongside the existing plant and treat almost half of the wastewater flow. Nereda’s technology represents a revolution in sustainable wastewater treatment and relies purely on biological action to purify effluent, before returning clean water to the environment. Aerobic, anoxic and anaerobic biological treatments take place in each Nereda reactor. Two 9,500m³ Nereda tanks were constructed to treat approximately 40% of the sewage coming to Garmerwolde, with effluent design targets for TN and TP of 7 and 1 mg/l respectively. These tanks were designed with a total capacity of 140,000 p.e. (30,000 m³ per day on average and 4,200 m³ per hour peak flow) and operate in parallel to the existing treatment works.

The Outcome

The Nereda plant has a much smaller footprint than conventional plants. At Garmerwolde, the Nereda facility takes up less than a quarter of the space occupied by the existing plant. As the innovative system uses totally biological action, it is a much more environmentally friendly solution than traditional methods, which use many chemicals to achieve the required treatment standard. Nereda also processes wastewater using significantly less energy, meaning it is cheaper to run, and provides sustainable low-cost wastewater service with minimum environmental impact. Nereda exceeded expectations at Garmerwolde and now treats 50% more wastewater than originally planned – 60% of the plant’s total output. The whole facility is now fully compliant with the treated water discharge requirements.

Nereda WWTP Garmerwolde, the Netherlands

Image: Footprint of the conventional plant (red) and the Nereda plant (blue) | © Google Maps & ARCGIS


Nereda Garmerwolde WWTP Upgrade - Videos

Interview Pascal Kamminga




  • Smaller footprint
  • Optimises treatment volumes
  • Efficient and clean
  • Almost chemical free
  • Lower power requirements
  • Real capital savings.

The local benefits of the project

Nereda logo small Smaller footprint
Nereda logo small Optimizes treatment volumes
Nereda logo small Efficient and clean 
Nereda logo small Almost chemical free
Nereda logo small  Lower power requirements