Dereham Water Recycling Centre (WRC) is situated in the Wensum Nutrient Neutrality catchment in Norfolk. The original works consisted of two treatment streams of primary settlement tanks, biofilters, humus tanks and tertiary sand filters and serves over 25,000 PE.
Following new flow to full treatment (FFT) legal requirements, the hydraulic capacity of the works was insufficient to comply with the increased capacity of 130.8 L/s (increased from 114 L/s). The upgrades were required by 31 March 2025 to meet Anglian Water’s FFT Water Industry National Environment Programme (WINEP) obligations.
Design & Engineering Challenges
Anglian Water designated the @one Alliance and its supply chain to deliver the upgrade project. Initial designs were based around a traditional sidestream solution including primary settlement tanks, submerged aerated filters, and high-rate sedimentation tanks. But, due to site space constraints, volume of enabling works, and planning approvals and environmental assessment delays; it was apparent that this approach was not viable. So, a review was undertaken and changed to a modular strategy.
A Modular Approach
The @one Alliance team selected a state-of-the-art modular sidestream treatment system featuring three modular technologies: lamella clarifiers, moving bed biofilm reactors (MBBR) and Dissolved air flotation (DAF) units.
A moving bed biofilm reactor (MBBR) was installed for each stream and supported with specialist MBBR media. The biomedia support the biological wastewater treatment processes under increased treatment load. The MBBRs improve final effluent quality and offer resilient, reliable and easy operation in comparison to traditional treatment plants.
The MBBRs were supplied by Siltbuster, who selected Warden Biomedia’s Bioflo+ specialist MBBR media. Bioflo+ is a durable, rugged media and ideal for MBBR treatment processes, providing a large, protected surface area (800m²/m³) for biofilm attachment and optimal conditions for the bacteria culture when the media are suspended in water. Bioflo+ features an innovative design which creates a high percentage of protected surface area for micro-organisms to adhere. In turn, this increases the overall biomass concentration and can reduce tank volumes required for wastewater treatment. Large openings allow for the wastewater to freely pass through the media which helps maintain a healthy and thin biofilm.
Project Success
Dereham WRC is now fully compliant with an increased FFT capacity of 130.8 l/s. This helps protect local waterways and the environment from untreated effluent discharges. The modular solution presented multiple benefits, including allowing flexibility and scalability. Additional units can be added easily, quickly and cost-effectively as and when required, the units are easier to access, maintain, ongoing operations are streamlined, and the MBBRs provide high performance while consuming less energy.
Overall, Dereham WRC demonstrates how modular, compact treatment solutions can deliver compliant, efficient, and resilient water treatment.
