Articles & Case Studies


Posted: Monday 14th September 2009

A MAJOR Severn Trent project to improve tertiary treatment at the Ray Hall WWTW has demonstrated the cost-effectiveness of refurbishment and asset optimisation as a practical approach to meeting Water Framework Directive water quality demands.

By replacing the sand and graded aggregate in the eight sand filter beds of the tertiary treatment process at the West Midlands WWTW, Hydro International’s Wastewater Service division helped ensure higher quality water discharges from the works.

Ray Hall is one of several WWTW benefiting from Severn Trent’s £400 million plus investment plan to improve the region’s facilities and meet Water Framework Directive standards.

Dominic Kowalewski, Project Manager for main contractor Morgan Est, comments: “There was a problem with the rapid gravity sand filters. Due to deterioration of sand quality, the backwash was not operating and the sand had become contaminated and clogged up.

“Hydro Wastewater Service Division offered us a very quick four month turn around, in fact finishing three weeks early, and took the whole project over from us so it was totally hassle-free.”

A total of eight 11 metre by 6 metre sand filters were refurbished, with the existing contaminated medium removed and disposed to landfill. All aeration and backwash nozzles on the bottom of the tanks were cleaned and many replaced, to restore efficiency.

One hundred tons of graded aggregates were sourced from the UK, to build up the filter beds, and this was completed by one hundred tons of the highest grade fine Dutch sand.

Ross Brace, Hydro Wastewater Division Service Manager adds: “Refurbishing and upgrading existing assets is a very cost-effective way of improving quality standards. Our expertise and experience means we can offer maintenance services on a very wide range of treatment processes at waste and potable water works.”

If you would like any further information on Hydro wastewater solutions, please call Hydro on 0800 269371, or visit

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