Evoqua is selected for a permanent installation of a CoMag system

Cost-effective CoMag ballasted clarification system installation reduces both total suspended solids and phosphorus


  • Algal blooms and poor river ecosystems are triggered by high levels of phosphorus in the river.
  • The UK Environment Agency’s National Environment Programme is imposing low phosphorus limits to combat the blooms and restore water bodies to “good” status
  • This impacts many wastewater treatment plants, including Lletty Brongu WWTW and Ruthin WWTW
  • The CoMag system will significantly decrease the amount of phosphorus that the works discharge and will ensure compliance with the new phosphorus limits of 0.5 mg/l and 0.25 mg/l respectively


Evoqua Water Technologies has been selected by Welsh Water and its design and construction partner, Mott Macdonald Bentley, to supply Evoqua’s CoMag® ballasted clarification system to reduce phosphorus in their effluent at both the Lletty Brongu WWTW in South Wales and Ruthin WWTW in North Wales. These will be the first wastewater treatment plants with a permanent installation of Evoqua’s ballasted settling technology in the ‘low P’ schemes for Welsh Water.

" After evaluating several technologies, we selected the CoMag system because it allows for a cost-effective solution to meet new phosphorus discharge limits "

Andrew Bowen, Head of Alliance for Welsh Water


The CoMag system uses magnetite – fully inert, iron ore particles – to enhance the clarification process. The system settles chemical floc up to 30 times faster than conventional clarification.



For communities that face challenging wastewater characteristics due to industrial discharge or dense increasing populations, the CoMag system is the ideal solution. The tertiary CoMag system will help Welsh Water reduce both total suspended solids and phosphorus before the treated water discharges into the local river.

‘’For both Lletty Brongu and Ruthin the CoMag system was compared in meticulous detail with a number of competing technologies,” said Simon Radford, UK Sales Manager of Evoqua’s Municipal Wastewater Treatment business. ‘’The combination of performance reliability to consistently produce reliable high-quality effluent with low Total Phosphate (T-P) and the excellent value that the CoMag system provides were crucial in making their system choice.”