Client: Yorkshire Water, Withernsea, UK
Date: July 15, 2021
Info: Municipal WwTP

Yorkshire Water's first new WwTP in many years is a No-Odour, No Sludge Aero-Fac® WwTP for the area around Withernsea. The new 15,000 population equivelant (PE) WwTP has been successfully treating sewage whilst automatically handling flow/loading fluctuations of up to 2x due to local tourism, all with very low energy, lower carbon footprint and little routine maintenance.

15,000 PE Aero-Fac® Routinely Handles 2x Peak Loads/Flows With No Operator Intervention, No Odour and No Sludge.

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Always-on Zero-to-Low Energy windpowered aeration is supplented by loading activated diffused air.

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Startup, commissioning and operation of the new Aero-Fac® WwTP at Withernsea was completed in 2021 after 4 years of joint study and planning by Yorkshire Water, Gurney Environmental and Stantec. Yorkshire Water had spent considerable time and effort researching various options, but saw excellent benefits from the well-proven and time-tested Aero-Fac® technology that has been successfully used elsewhere in England and Scotland over the past two decades.

Over twenty years ago in 2000, Montgomery Watson Projects (now Stantec) constructed the first Aero-Fac® WwTP in the UK for Tayside Regional Council/North of Scotland Water Authority (NoSWA) at Errol, Scotland. In 2019 Gurney Environmental Ltd and Stantec worked with Yorkshire Water to develop Yorkshire's 15,000 PE WwTP at Withernsea that is currently the largest Aero-Fac® WwTP in the UK, and was selected in place of the activated sludge plant that had been initially proposed.

Aero-Fac® Provides Extraordinary Flow Variation Capability

The designers at Gurney Environmental developed this Aero-Fac® wastewater system for Yorkshire Water to meet a winter population of about 7,100, but rising to a summer population of about 14,713! This dramatic doubling in flow from winter to summer can create serious issues for many WwTP designs.

In the analysis by Yorkshire Water, 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.

Significant OPEX Cost Reductions

While Aero-Fac® handles massive flow variations without significant operator intervention, the unique wastewater treatment system also utilises always-operating renewable wind energy for constant aeration plus an extremely low operating and maintenance cost loading-activated diffused air aeration system when needed. 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.

Yorkshire Water’s Communications Advisor John Bond had this to say: “Our proposal is a step away from traditional treatment works and means we are opting for a much greener, more environmentally friendly option. The new proposal means construction times will be reduced, traffic movements can be minimised and once finished, the site will be virtually noise free.”

Selecting The Best “Total-Life-Cost” Solution

Bond went on to say, “In addition, visual impacts and the risk of odour will be greatly reduced. Our existing facility in Hollym, near Withernsea needs to be replaced as it is now only 40 metres from the sea due to rapid coastal erosion in the area. By building a new treatment facility inland, we’re able to look at new, alternative options for treating the town’s wastewater, and we feel Gurney Environmental’s experience and track record provide us with the best solution for both ourselves and our customers for the future.”

Enhanced, Lower-cost Disinfection

As an example of a “greener”, lower maintenance and cost approach, the UV system typically required by the Environment Agency was engineered out of the Withernsea WwTP as a result of monitoring carried out by Stantec at other Aero-Fac® wastewater treatment plants around the UK that demonstrated that the wwtp had met the discharge requirements without the need for UV.

The unique combination of inherent disinfection provided by stabilisation ponds, enhanced by the continual gentle mixing provided by Gurney Environmental's unique wind powered SERIES 3 aerator/mixers ensure that cell contents are repeatedly exposed to the sun for natural UV kill. This inherent benefit combined with longer retention/ stabilisation times produces an effluent that is safe for irrigation reuse, which according to the EU and various articles and papers on climate change, is going to be needed in the future. This also has the advantage where wastewater treatment systems can operate with better disinfection capabilities and require smaller or even no tertiary disinfection.

Modular Design of Aero-Fac® Allows Easy Scaling From Smaller up to Peri-Urban WwTPs

Aero-Fac® systems are generally configured with both primary and secondary stages of treatment (a third stage is optional when needed). Each “train” or “module” of parallel cells can provide 100% on-site treatment including enhanced disinfection and full nitrification. Modules are designed with correct length-to-width ratios for proper flow and uniform loading, and built to a maximum size for controlled, predictable performance.

As flows increase, additional trains or modules are added, thereby providing a true scalability. The use of a modular design also allows for the ability to use a distributed or multi-location design scheme for larger applications including peri-urban scenarios.


Understanding Aero-Fac® Technology

          • 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. 

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:

    1. Full treatment, standalone solutions (Aero-Fac® and Accel-o-Fac®);
    2. Pretreatment systems to solve issues and expand existing filter plants (Aero-Fac® PTS); and
    3. 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.