New ViroSewage™ Technology (or ViroFilter™ Technology as it is known in the UK)

Phosphate consents on final effluent discharges from Wastewater Treatment Plants (WWTPs) are being increasingly tightened. As a result the water companies in the UK are faced with additional treatment requirements, these being biological, chemical or physical. Finding the best application can often be problematic and the associated costs may be high.

ViroSewage™ Technology, developed by Virotec International, provides a simple yet robust solution to remove both phosphates and metals from the wastewater flow prior to effluent discharge. A pelletised form of treatment has been developed; this is a passive "flow through" system eliminating the need for chemical addition for phosphate removal.

The technology can be applied at both small and larger WWTPs. At smaller treatment plants    (< 2,000 population equivalent), typical operation may involve a Rotating Biological Contactor (RBC) followed by a reed bed. The gravel in a reed bed would instead be replaced with ViroSewage™ pelletised media, which could also operate at shorter residence times giving a smaller footprint. The phosphates and metals are removed with no need for any ferric chloride dosing.

At larger scale (> 10,000 p.e.), when ferric is added before and/or after a biological filtration plant, a sand bed is often used to prevent iron carry-over in the effluent. However, a ViroSewage™ pellet bed alone can eliminate the need for ferric dosing and work in place of the sand bed for final effluent polishing, including phosphate and metal removal.

6-month trial just completed by UK's Water Research Council

Six months ago a demonstration trial was undertaken with the Water Research Council (WRc) to further evaluate the application of a bed of pelletised ViroSewage™ reagent. Whilst the pellet systems have been scaled-up in other market areas, this trial was tailored specifically to the UK water industry.

The WRc trial confirmed the performance and the longevity of the ViroSewage™ Technology on a larger scale and reviewed options for system design and configuration on future installations for the UK Water Companies. A filter bed incorporating ViroSewage™ reagents can now be integrated at the back end of a waste water treatment plant, providing passive flow-through treatment for phosphate removal and final effluent polishing.

Virotec's Executive Chairman Mr Brian Sheeran explains, "This application offers the water industry an economic and sustainable alternative to chemical addition."

WRc Trial Summary

Two beds containing ViroSewage™ pellet media were operated with a horizontal flow reed bed type configuration at residence times varying between 4 and 12 hours. The work demonstrated that up to 85% phosphate removal could be achieved meeting with consents of less than 2mg/l.

On trial completion, after six months of continuous operation, the phosphate removal capacity of the ViroSewage™ media had exceeded 7gP/kg ViroSewage™ pellets but the pellets were not close to exhaustion. In addition, some earlier bench scale trials have now been operating for over 18 months. More than 1,500 bed volumes have been processed and the phosphate removal capacity of these pellets has exceeded 15gP/kg ViroSewage™ pellets. This work is still ongoing and again has yet to demonstrate signs that the ViroSewage™ media may be close to exhaustion.

The full report prepared by WRc can be viewed by clicking here.