Cost-efficient Hybrid-SAF™ permanently replaces RBC for United Utilities

The Hybrid-SAF™ enhanced biological treatment process will be retrofitted into the existing rotating biological contactor (RBC) tank at the United Utilities, Mowpen Brow wastewater treatment works site near Knutsford, Cheshire.

The precision-engineered submerged moving-bed, fixed-film technology was developed in-house and can be retrofitted into any vessel, regardless of shape or size. The team worked closely with United Utilities to identify the most effective and cost-efficient solution for the Mowpen Brow works once it was decided to replace the RBC.

By repurposing existing onsite infrastructure, rather than ripping-out and reinstalling the tank, the utility will make significant cost-savings and reduce environmental impact. Disruption to the local community will also be minimised, with fewer vehicle movements required.

The installation will increase total capacity at Mowpen Brow, which serves approximately 300 population equivalent. It will also deliver highly efficient wastewater processing, meeting the descriptive environmental consent.

Andrew Baird, technical director,  said, “We worked in partnership with United Utilities for over 20 years and we’re delighted with this latest contract win.

“The modular nature of the Hybrid-SAF means the technology is highly adaptable to existing vessels of different shapes and sizes. At a restricted site like Mowpen Brow, it may be one of few options available.”

A recent installation of the Hybrid-SAF for Wessex Water at Sherborne wastewater treatment works doubled capacity and delivered a cost-saving of approximately 75% in capital expenditure. In addition, the operator maintenance requirement is low when compared with competitor technologies and there are no moving parts.

We have already undertaken the design work for the Hybrid-SAF for Mowpen Brow and the system will be manufactured off-site in factory conditions. Installation takes place in July with commissioning in August.

Illustration above: The repurposed rotating biological contactor (RBC) tank retrofitted with a primary settlement, biological (Hybrid-SAF) and final settlement process treatment stages.

Baird said, “Water and sewerage companies are under increasing pressure from the regulator to deliver better value for their customers and we are seeing strong interest in the Hybrid-SAF. We have a long history of design-for-manufacture-and-assembly (DfMA) treatment systems and trusted partnerships with many UK utilities so we are well-placed to support these objectives.”