The No-Odour, No Sludge Aero-Fac® WwTP operated by Northumbrian Water for the area around Waren Mill has been successfully treating sewage whilst automatically handling flow/loading fluctuations of up to 10x due to local tourism, all with little energy and little routine maintenance.
Waren Mill Aero-Fac® Routinely Handles 10x Peak Loads/Flows With No Operator Intervention, No Odour and No Sludge.
L-R: Heidi Mottram, Anne-Marie Trevelyan, David Richardson, Louise Hunter
In 2019, Northumbrian Water completed the construction at Waren Mill of an extraordinarily flexible, low carbon footprint, dramatically low Total Life Cost Aero-Fac® wastewater treatment system supplied by Gurney Environmental. The Waren Mill scheme is NWG’s first facultative lagoon to treat wastewater, and one of several similar facilities in the UK. Anne-Marie Trevelyan, MP for Berwick-upon-Tweed, has visited Northumbrian Water’s new Aero-Fac® WwTP at Waren Mill, just outside Bamburgh. Accompanied by local councillor Guy Renner-Thompson, Anne-Marie met Northumbrian Water Group (NWG) CEO Heidi Mottram, plus NWG Director of Corporate Affairs Louise Hunter, and David Richardson who manages the site.
The MP’s press release stated, "The eco-friendly way of treating wastewater is low on power costs and needs little maintenance, making it a preferred option where there is space to install large lagoons.
"The surrounding area has a high transient tourist population, and the addition of the Budle Bay campsite some years ago meant the existing treatment centre was undersized and required an upgrade. The twin-lagoon system provides a long-term solution to the changes in capacity required throughout the year."
Ms Trevelyan was given a tour of the site so that she could see the WwTP for herself. She was also shown the new pumping station near the centre of the village which helps sewerage reach the WwTP.
She said: “I am delighted to see the final result of this project for myself, and I congratulate Northumbrian Water Group on their fantastic facility which will serve local residents and visitors for decades to come.”
Extraordinary Flow Variation Capability
The designers at Gurney Environmental developed this specific Aero-Fac® wastewater system for Northumbrian Water to meet a normal winter population of 200, but rising to a summer population of almost 3,000! This dramatic variation in flow from winter to summer can create serious issues for many WwTP designs. At this particular location, Northumbrian Water had been tankering away excess wastewater flows over the 150-pe SAF design with an associated high operating cost and carbon footprint.
In the analysis by Northumbrian Water’s consultants, Aero-Fac® offered a well-proven and time-tested system with the flexibility and robustness of operation to be able to cost-effectively and easily accommodate this large flow variation.
In the past year, especially with the covid pandemic, the nearby caravan site was full, so the WwTP had a high load summer. However, with the new Aero-Fac® system, Northumbrian Water have finally had a year with no tankering!
Significant OPEX Cost Reductions
While Aero-Fac® handles massive flow variations without significant operator intervention, the unique wastewater treatment system also utilises renewable wind energy and extremely low operating and maintenance cost aeration systems. Total annual operating costs are typically around 85% less than conventional activated sludge systems.
Aero-Fac® also requires no sludge handling, removal, testing or disposal by completely self-digesting sludge within the system itself, thereby providing a truly long-term sustainable, low TOTEX, complete and total on-site solution.

Click to Enlarge Drawing
Understanding Aero-Fac® Technology
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- The all-stainless diffused air system is designed to normally be in the off-state, activated automatically by a dissolved oxygen monitor only when required by increased demand.
- The diffusers are self-cleaning and require virtually no routine maintenance. The low-pressure fan blowers have a very low wear factor with minor ongoing routine maintenance.
- The Aero-Fac® WwTP is also equipped with wind-powered SERIES 3 aerator/mixers that provide constant aeration and balanced loading throughout the treatment cells with zero-to-low energy costs. These units provide the supplemental oxygen and overall cell optimisation for early-years or off-peak low-flow/load situations.
- When oxygen demand exceeds their capability, the powerful diffused air system automatically kicks in to handle larger flows/loads when and if needed.
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Proven Track Record of Performance
Several Unique Wastewater Treatment Solutions from Gurney Environmental
Gurney Environmental offer several systems and variations of the Aero-Fac® system that include:
- Full treatment, standalone solutions (Aero-Fac® and Accel-o-Fac®);
- Pretreatment systems to solve issues and expand existing filter plants (Aero-Fac® PTS); and
- Standalone sludge digestion systems (Aero-Fac® SDS).
The very unique and economical Accel-o-Fac® system, as an example, offers a zero-to-low energy solution that provides incredibly low OPEX with very low initial CAPEX. In many cases, no energy costs plus no sludge handling costs or complexities make Accel-o-Fac® extraordinarily sustainable and economical initially and long-term. Accel-o-Fac® has been used for over a decade in the UK at such locations as Holkham Hall and Village.