DynaSand® Oxy filters in year-long optimisation trail at Watton Water Recycling Centre
To demonstrate the ability of Hydro International’s DynaSand® Oxy to remove ammonia and phosphorous from wastewater in a single stage.
Watton STW is a conventional percolating filter works with a population equivalent 13,900 in Norfolk. Anglian Water selected this site to evaluate the Hydro International, DynaSand® Oxy filter as part of the Chemicals Investigation Programme 2 (CIP2) scheme to reduce both phosphorus and ammonia in a single treatment stage.
Whilst phosphorus removal was the priority for the trial, it was agreed by the CIP2 technical working group that it would be beneficial to demonstrate whether nitrification could also be achieved in a single tertiary treatment stage. The DynaSand® filter, with chemical dosing, is already an accepted technology for maintaining very low effluent levels of phosphorus, with 0.1 to 0.2 mg/l being achieved as an annual average at multiple European sites.
The DynaSand® Oxy trial at the Watton plant consisted of six DynaSand® DS7000 (2 m diameter) Oxy filters, commissioned over the winter of 2015.
A full 13-month trial was performed from the beginning of February 2016 to the end of February 2017. The trial was commissioned by Steve Riley of Anglian Water. Ferric sulfate was dosed at the inlet to the filters via a static mixer at 5 mg/l Fe to precipitate phosphorus salts for removal. Changes to plant operation were minimised.
When the plant is operating optimally without other external factors causing an increase in the phosphorus load to the filters, the results demonstrate that an effluent total P concentration of 0.20 mg/l can be achieved.