No nitrate for Yorks

Yorkshire Water has awarded a Nitrate Removal Scheme contract worth more than £4M to civil engineering company Mott MacDonald Bentley (MMB), a joint venture between JN Bentley and Mott MacDonald based in North Yorkshire.

As a result, MMB has appointed ACWA Services in Skipton as M&E subcontrac-tor, to design, supply, install and commission its innovative NITREAT technology for the removal of nitrate from drinking water. The new plant, to be installed at Yorkshire Water’s Keldgate WTW, is due for commissioning by the end of 2009 and will be the largest of its kind in the UK water industry.

The Keldgate WTW, which draws groundwater from natural borehole supplies, is located in a rural farming area identified as one of Defra’s Nitrate Vulnerable Zones. Tests have indicated that the nitrate level in the water supply has been increasing steadily for some time, and while current levels are acceptable, without intervention it could reach levels of 63mg/l by 2025. This is much higher than the Prescribed Concentration Value (PVC) of 50mg/l and a major factor in Yorkshire Water’s decision to take pre-emptive action.

Meanwhile, the Huddersfield-based screenings and screenings-handling equipment supplier Longwood Engineering has completed the upgrade of three existing Longwood Escalator screens at Naburn, one of the main wastewater treatment works for the city of York. The project was part of a wider programme of work undertaken by primary contractor Costain to allow for increased screening requirements and to meet the new Yorkshire Water Asset Standards for Inlet Works design.

The project involved refurbishing three escalator screens with new elements and chains and installing three new tanks to help improved flow characteristics to the screens. Work had to be undertaken while maintaining full screening capacity for full flow through the treatment works at all times, and there was concern that with the removal of the first screen, the two remaining screens would not be capable of handling the flow.

Longwood Engineering’s solution was to fit two new brushes to the two remaining screens to handle the flow as efficiently as possible while the first screen was removed. With these in place, the refurbishment work could then begin.

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