The paper will explain the principals behind the unique ballasted clarification process (CoMag) and why it was adopted at one of Severn Trent’s largest treatment works (Finham STW near Coventry). CoMag uses a high-density ballast (magnetite) that embeds itself into the precipitated solids and binds the phosphate into a particle for rapid settlement. This results in exceptional effluent quality that is both consistent and reliable in terms of Suspended solids and Total Phosphate and therefore, safe to discharge to meet new EA standards. Phosphate discharge from CoMag plants are regularly operating at < 0.1 mg/l T-P.
The Speakers will then discuss the suitability of CoMag specifically for the Finham STW and why the process was accepted as the best option for the site. In particular, how the plant is being retrofitted into existing structures and how the ballasted solids produced from the CoMag process are settled in only 2 specially designed CoMag clarifiers (equivalent to 12 conventional clarifiers).
Finally, the speakers will discuss the implementation of the CoMag process at the site, the installation of this very large capacity plant (FTFT of 2,588 Litres/s) and the benefits and challenges of adopting existing site infrastructure for the CoMag process.