Articles & Case Studies

Salmon to return to River Don following sewage works upgrade

Posted: Tuesday 7th June 2016

The River Don is cleaner now than at any time since the Industrial Revolution, thanks in part to a £78m scheme to improve the Blackburn Meadows Sewage Treatment Works in Sheffield.

Much of the new equipment at the sewage treatment works was designed, manufactured, installed and commissioned by A&J Fabtech of Dewsbury in West Yorkshire, who also refurbished some of the existing equipment.

There has been a treatment works on the site for over 130 years; today it serves nearly 800,000 homes and businesses across South Yorkshire. The upgrade works also incorporate a storm overflow scheme which reduces the likelihood of damaging flooding in the area, a critical function as the works is only a stone's throw from the 280-store Meadow Hall shopping centre.

The project to upgrade Blackburn Meadows started in 2012, with the initial objective being to reduce the levels of ammonia in the River Don so that a balanced and more natural ecosystem could develop. It has continued in stages and is now a state-of-the-art facility that ensures water quality capable of supporting a diverse plant and animal wildlife profile.

A&J Fabtech has played a major role in the sewage treatment aspects of this project, including the refurbishment of existing equipment and the installation of new settlement tanks.

"The existing tanks were based on a 1960s design, so were a lot deeper than modern tanks but otherwise very similar," explains Shaun Brosnan, A&J Fabtech's Contract Manager for Blackburn Meadows. "It made sense to refurbish these, and build some completely new ones to add extra capacity."

The new tanks are fitted with three-quarter bridge scrapers for the activated sludge process (ASP). A&J Fabtech also supplied GRP launders, a drop box, weir plates, a weir cleaning system, dipping scum box, slip rings, loss of rotation sensors, torque limiting sensors, and a scum concentration collection system.

Refurbishing the existing tanks included removal of their existing three-quarter bridges and installation of new ones, while the Mckinney baffles were upgraded from 5m to 8.2m diameter to provide enhanced flow control in the effluent channel. As with the new tanks, a weir cleaning system, dipping scum box, slip rings, loss of rotation sensors, torque limiting sensors and scum concentration collection system have also been provided.

The increased treatment capacity, especially in terms of secondary treatment processes, has been instrumental in reducing the ammonia levels in the final effluent that is discharged to the River Don. Under the European Freshwater Fish Directive, the treatment works is required to achieve a level of 3 mg/l or less of ammonia in order to comply.

Since the refurbishment of Blackburn Meadows, there have been regular sightings of trout in the city centre reaches of the River Don.




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