Knostrop Sewage Treatment Works Upgrade (Phosphorus Reduction)
Knostrop, Leeds, West Yorkshire · 2022-2025 (Construction started April 2022, completion October 2024, regulatory date December 2024, EBPR completion April 2025) · £60m
The judgement call
Account-gated at launchChosen EBPR layout is a modified Johannesburg configuration - Under-pressure tappings and commissioning valves used to facilitate work and enable new pipelines to be laid offline - Staggered upgrade of aeration lanes to enable continued treatment - Significant reduction in energy consumption (28% decrease in ASP2 blower energy) due to new blowers and Ammonia-based aeration control (ABAC) - CoMag® TSR was the largest of its kind installed at the time of construction
Key engineering challenges
Achieving compliance with new Total Phosphorus and Total Iron permit levels (0.4 mg/l Total Phosphorus and 4 mg/l Total Iron) - Integrating Enhanced Biological Phosphorus Removal (EBPR) and CoMag® tertiary solids removal into existing plant - Maintaining process running while diverting RAS flow and commissioning new assets - Reducing energy consumption while increasing treatment capacity and meeting stricter environmental standards
Project facts
- Client / owner
- Yorkshire Water
- Lead contractor
- Ward & Burke (primary delivery contractor)
- Lead designers
- Stantec UK (outline design), Yorkshire Water (design assurance), Sweco (design assistance & hazard study facilitators)
- Project type
- upgrade
- Scale
- Treats wastewater of almost one million people; Rate of 5,600 litres per second; New 14,000m³ RAS anoxic tank; CoMag® TSR treats 4,032 l/s; 14 aeration lanes upgraded
- Disciplines
- Civil; process; environmental; mechanical; electrical; digital engineering
- Standards & frameworks
- AMP7 Water Industry National Environment Programme (WINEP); Water Framework Directive
Sources: Yorkshire Water: https://www.yorkshirewater.com/news-media/news-articles/2023/60m-project-at-yorkshire-water-s-knostrop-treatment-works-to-reduce-phosphorus-entering-river-aire/ (Accessed: 2026-06-10) - WaterProjectsOnline: https://waterprojectsonline.com/case-studies/knostrop-stw-2025/ (Accessed: 2026-06-10)