Evoqua installs its first BioMag system in a European sewage plant

A permanent BioMag system is used to increase output and reduce phosphorus at a sewage treatment works facility


  • Rugby will be Europe’s first wastewater treatment plant with a permanent installation of Evoqua’s ballasted BioMag system settling technology
  • This settling technology has been proven in facilities throughout the United States for more than 7 years
  • Evoqua Water Technologies has been selected by Severn Trent Water and its design and construction partner, Costain, to supply Evoqua’s BioMag® ballasted clarification system
  • Their goal is to both increase output and reduce phosphorus at the Rugby Sewage Treatment Works



Algal blooms and poor river ecosystems are triggered by high levels of phosphorus in the river. To combat the blooms and restore water bodies to “good” status, the UK Environment Agency’s National Environment Programme (NEP) is imposing low phosphorus limits on many wastewater treatment plants, including Rugby. The introduction of the BioMag system will significantly decrease the amount of phosphorus that the works discharges, making this an important step to achieving compliance with the new phosphorus limit of 0.4 mg/l of total phosphorus (T-P).

" Rugby is a thriving market town and in order to improve the waterbodies in its catchment, a significant enhancement to the treated water quality and capacity for growth is going to be delivered by upgrading the existing sewage treatment works using the BioMag system. Conventional treatment methods would have required a large expansion at a higher cost, however by transferring this innovative technology from North America and following UK water industry funded pilot trials, the BioMag system will help Severn Trent deliver its customer funded objectives and continue to offer the cheapest customer bills in the UK. "

Ed Ruswa, Senior Process Design Engineer for Severn Trent Water


The BioMag system uses the addition of magnetite – fully inert, iron ore particles – to enhance the existing Activated Sludge process. As a result, the settlement across the existing Final Settlement Tanks is greatly improved even with the predicted 25% increase in flow anticipated at the works. For communities that face challenging wastewater characteristics due to industrial discharge or dense populations, the BioMag system is the ideal solution. The BioMag system will help Severn Trent Water reduce both total suspended solids and phosphorus before the treated water discharges into the River Avon.

‘’For Rugby, the new BioMag system will be installed to combat both the new phosphorus limit and the expected increase in the local population, which means that the plant will be able to treat more effluent waste to a better quality.’’ explains Simon Radford, UK Sales Manager of Evoqua’s Wastewater Treatment business. ’’As an alternative to adding more Final Settlement Tanks, the BioMag system allows the user to get more out of their existing assets at a fraction of the cost of such major new civil structures.”