Yeovil Pen Mill WRC 

During AMP7 over 800 sites were required to meet tighter phosphorus permits under the National P Removal Programme. The majority of these sites adopted the solution of using tertiary solids removal (TSR) plant with ferric or aluminium dosing to meet the permit requirements. There are 6 major TSR plant suppliers in the UK, three of which use the same technology, each with its unique feature, competing in the P removal market. This has driven the TSR technologies to evolve and improve, addressing the needs to enhance reliability and to minimise the use of chemicals whilst meeting increasingly stringent standards. During AMP7, Wessex Water installed 14 FilterClear plants across its region for phosphorus removal, ranging from small sites less than 4,000 population to large sites over 75,000 population. Yeovil Pen Mill Wastewater Recycling Centre (WRC) is the largest site among these.

Project background

Yeovil WRC in Somerset is a large treatment works owned by Wessex Water, serving a population equivalent (PE) over 75,000 (including trade discharge). The existing treatment processes comprised:

• Primary settlement tanks.
• High-rate plastic media filters.
• Intermediate humus tanks.
• Trickling filters (slag media).
• Humus tanks.

To meet tightened consent requirements, a major upgrade was required during AMP7; comprising tertiary MBBR plant and a tertiary solids removal (TSR) plant.

The TSR plant with chemical dosing is required to achieve the total phosphorus (TP) consent of 0.5 mg/l. On a whole life cost basis, taking into account process reliability, delivery programme, power demands, chemical consumption and maintenance requirements Bluewater Bio’s FilterClear was identified as the preferred solution, and the contract was awarded in May 2022.