Yorkshire embarks on £60m sewage plant upgrade

Yorkshire Water has begun a £60 million upgrade at its largest sewage plant to reduce the amount of phosphorous in treatment wastewater.

Under the Water Framework Directive, companies treating wastewater are obliged to reduce phosphorous levels in final effluent to 0.4mg/l.

During this asset management period (AMP7), Yorkshire will invest £790 million to comply with these targets across its region.

The Knostrop plant processes 5,600 litres of wastewater per second from a population of around one million people, with treated effluent returned to the river Aire.

The company will add enhanced biological phosphorus removal (EBPR) processes at the biological treatment stage and build a solids removal plant to treat the final effluent.

The process uses organisms to remove large amounts of phosphorous from wastewater, which the company said significantly reduces levels within the effluent in a sustainable way.

“We are committed to improving water quality in the rivers across our region,” Rachael Fox, head of programme delivery said. “One of the key focuses is the reduction of Phosphorus entering rivers in the treated wastewater we return to the environment. Reducing Phosphorus levels can make a real difference to water quality in our rivers.”

The Environment Agency said despite significant progress in reducing river phosphorous over the past 30 years, the level of non-compliance with good ecological status for phosphorous at a national level remains high.

The issue is worse in densely populated areas and the Environment Agency said climate change is likely to exacerbate the risks and impacts.

In a December 2022 report, the Environment Agency advised a mixture of national and catchment-based planning to reduce phosphorous levels but warned the timescales for improving water bodies may be several decades.