Designing a nature-based wastewater treatment solution to improve river water quality and reduce carbon
Project overview
Binnies supported the delivery of Anglian Water’s first integrated constructed treatment wetland (ICW) at Everton Water Recycling Centre in Bedfordshire, providing specialist wetland design for a pioneering nature-based wastewater treatment solution.
Serving around 200 homes and a population of approximately 600, Everton Water Recycling Centre required a sustainable solution to meet tighter Environmental Permitting Regulations consent limits for phosphorus and iron. The site needed to reduce phosphorus in its discharge to comply with Environment Agency AMP7 requirements and the Water Industry National Environment Programme.
Rather than defaulting to a conventional chemical dosing solution, the project team developed an innovative gravity-fed wetland that uses natural treatment processes to improve water quality before discharge to the River Ivel.
Project highlights
Anglian Water’s first integrated constructed treatment wetland
Three-cell wetland covering 18,320 m²
More than 110,000 native wetland plants established
Achieved an 84% reduction in carbon emissions, reducing the carbon footprint from 654 tCO₂e to 104 tCO₂e
Created a repeatable design approach to inform future wetlands planned across AMP8
Eliminated the need for chemical dosing, reducing lorry movements, operational carbon and long-term chemical costs
The challenge
Everton Water Recycling Centre is located downslope from Everton village and benefits from a 14% gradient, enabling wastewater to flow to the site by gravity before treatment and discharge to the River Ivel.
To meet new consent limits of 1 mg/l phosphorus and 8000 µg/l iron, Anglian Water needed a solution that would ensure regulatory compliance while minimising long-term operational impacts.
The conventional wastewater treatment approach of iron dosing would have required major civil works, a new concrete base, modifications to the existing process and a continuing supply of iron chemicals. This would have introduced ongoing costs, increased carbon emissions from deliveries and greater operational complexity.
The project had to overcome significant delivery challenges, including land acquisition and planning permission, seasonal working constraints, stakeholder coordination and the risks associated with validating a first integrated constructed treatment wetland for Anglian Water for stringent phosphorus and iron limits without chemical dosing.
Our role
As one of the wetland designers, Binnies contributed to the development of the ICW solution alongside VESI Environmental Ltd.
The final design created a three-cell wetland covering 18,320 m², equivalent to around 2.5 football pitches. The wetland diverts treated wastewater through a gravity-fed treatment system before reconnecting with the existing outfall pipeline at the new wetland outfall location.
By helping to deliver a nature-based alternative to chemical dosing, Binnies supported a solution that avoided the need for a new dosing plant and enabled the team to make use of existing site infrastructure and avoid the need for a new dosing plant and associated power requirements.
The approach also creates a robust, repeatable, sustainable design approach that will inform future treatment wetlands planned across AMP8.
Creating value through nature-based design
The wetland was delivered over a six-month construction and planting period, during which three wetland cells were excavated and more than 110,000 native plants were established. Utilising site-won clay soils as a natural liner, the excavated clay was used in the bunds around the new cells, removing the need to import or export large volumes of material and avoiding hundreds of lorry journeys, further reducing the carbon footprint and construction costs. The planting included emergent wetland species such as lesser pond sedge, reed sweet grass, lesser reedmace and yellow flag iris, alongside marginal wetland species including water mint, purple loosestrife, brooklime, flowering rush, marsh marigold, meadowsweet and water forget-me-not.
This combination of engineering and ecology enables the wetland to deliver water quality compliance while creating new wetland habitat and supporting biodiversity.
Outcomes and benefits
The ICW provides a nature-based route to meeting phosphorus and iron consent limits, helping Anglian Water comply with environmental requirements without relying on conventional chemical dosing.
By eliminating the need for chemical dosing, the project reduced lorry movements, operational carbon and long-term chemical costs.
The project achieved an 84% reduction in carbon emissions, cutting the carbon footprint from 654 tCO₂e to 104 tCO₂e. This was largely achieved through balanced cut-and-fill earthworks that avoided imports and exports, and by removing 99% of the anticipated concrete use.
The wetland creates new habitat through the establishment of more than 110,000 native plants and the inclusion of a deeper pond area designed to encourage biodiversity and support local wildlife.
The project demonstrates how nature-based design can deliver regulatory compliance while providing long-term environmental, operational and carbon benefits. Lessons from the Everton ICW will help shape the next generation of wetlands to be delivered across AMP8 as part of a £37 million wetland programme.
Enhancing lives, communities and the environment
The Everton integrated constructed wetland shows how nature-based design can transform a regulatory challenge into a long-term environmental opportunity. Through its wetland design role, Binnies helped support a low-carbon treatment solution that avoids the need for conventional chemical dosing, that improves water quality, reduces operational impacts and creates new habitat for wildlife.
By replacing conventional treatment infrastructure with a natural wetland system, the project provides a practical blueprint for sustainable, resilient wastewater treatment across future AMP8 programmes.