Clay Mills Upgrade Delivers Long-Term Benefits with New Mixers

Sixteen Chemineer (UK) anoxic mixers, manufactured by NOV, have completed two years of uninterrupted service at Clay Mills STW, Severn Trent Water’s new Bio-P Activated Sludge Plant. The Clay Mills upgrade was a £40 million design and construct contract by MWH Treatment as part of the e5 Alliance.

Serving a domestic population of approximately 100,000 in the brewing town of Burton upon Trent, the works receives a very significant trade load, resulting in a population equivalent (PE) of 421,879 with a FFT (flow to full treatment) of 112,665m3/d and a DWF (dry weather flow) of 47,000m3/d. As part of AMP5, Clay Mills was given a revised and more stringent quality obligation under the UWWTD (urban waste water treatment directive) P (phosphorus) removal legislation.

In the Activated Sludge Plant (ASP), which has a volume of 30,000m3 split into four double-pass lanes, the slow speed, paddle-type GT Chemineer anoxic mixers have been suspending waste sludge solids and providing complete basin mixing, as Richard Thomson, e5 Project Manager, explains: 

“The Chemineer anoxic mixers have proved to be very robust and reliable. They have continually eliminated oxygen incorporation from the liquid surface with no swirl or vortex. They have a proven track record of performance on a number of Severn Trent sites including their largest at Minworth”.

Built with a high-efficiency gearbox specifically for agitator service, the modular Chemineer GT mixers have an optimised gear design and lighter weight shaft diameter requirements that makes them very energy-efficient. They also have a quick and easy seal change capability that saves time and reduces maintenance costs.

Throughout the upgrade, close collaboration and knowledge-sharing between the e5 partners and the supply chain produced innovations that generated value engineering savings of £2.6M.