Biological phosphorus removal to meet UWWTD tightening discharge consent is central to the Biwater Treatment contract at the Severn Trent Water Ledbury wastewater treatment works in Herefordshire.

Biological phosphorus removal to meet UWWTD tightening discharge consent is central to the Biwater Treatment contract at the Severn Trent Water Ledbury wastewater treatment works in Herefordshire. The GBP6.1m project also includes storm water CSO screening at the main feed pumping station and provision for a future tertiary treatment stage. Completion is scheduled for March 2005.

Designed for a population equivalent of 13,930, the new plant will treat a process flow of 132 L/s to a final effluent standard of BOD 10: suspended solids 20: ammonia 3 (summer) and 5 (winter) mg/l.

The process incorporates 6mm screening, grit removal, crude sewage and RAS conditioning, two diffused air oxidation ditches for biological phosphorus removal, final settlement, odour control to the inlet works, RAS/SAS pumping, SAS thickening and new MCC/power distribution.