Wessex Water achieves 75% saving with enhanced process

Published on by in Case Studies

Wessex Water achieves 75% saving with enhanced process

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Population growth in the town of Sherborne in Dorset meant that the rural water recycling facility owned and operated by Wessex Water required an upgrade to manage overload. Initially the utility was planning to construct two to three additional 30m-diameter trickling filters, but such a development posed an issue around footprint on this land-constrained site. 

 

Instead, the utility was looking for an alternative solution and was scouting for high-rate processes and ways of utilising existing abandoned structures onsite. Andrew Gulliford, process design manager at Wessex Water, identified WPL’s enhanced biological treatment process via an article in an industry publication and invited the company to the Sherborne site. 

 

A key advantage of WPL’s Hybrid-SAF™precision-engineered treatment system is that it can be retrofitted into any vessel, regardless of shape or size, to deliver more efficient wastewater processing. During the initial collaborative planning stages of the project, the repurposing potential of an abandoned 12m-diameter onsite sludge tank was identified. 

 

Together the partners calculated that a potential cost-saving of 75% in capital expenditure could be achieved by retrofitting this existing infrastructure with WPL’s technology as an alternative to the planned project. WPL’s Hybrid-SAF technology comprises a submerged moving-bed, fixed-film reactor and can treat wastewater in a more sustainable and cost-effective way than traditional submerged aerated filters (SAFs). 

 

Doubling capacity 

 

Retrofitting the circular vessel with modular WPL Hybrid-SAF cells could utilise the entirety of the vessel, whilst providing secondary biological treatment for 50% of the works’ flow-to-full-treatment. By doubling the process capacity, a permanent alternative to the planned trickling filters was identified and, looking at a 20-year horizon, one that was significantly cheaper.

 

Off-site manufacture of the modular process technology cells meant that the onsite project delivery time would be a couple of days, rather than a possible 12-months for the civils work required for new trickling filters.  

 

WPL’s technical director Andrew Baird says, “WPL’s Hybrid-SAF is a significant step forward for submerged biological treatment. Our research and development team hasconceived the hydrodynamic profile underpinning the technology in a new way, which has been made possible by the use of a high specific surface area media. 

 

“The result is that significant process efficiency advantages have been achieved, including reductions in cost, physical footprint and electricity consumption, all whilst increasing the overall process capacity of the site and improving environmental compliance. Being involved in the project at the start and working collaboratively with Wessex Water meant the best solution for the site could be identified very early on.”

 

The first flows entered the system on 1 October 2018 and the first data was recorded on 30 October. Results showed ammonia (NH3) levels at

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