Modularised Delivery of Ceramic Membrane Plant at Alderney WTW

RSE has been engaged by South West Water (SWW) to provide the design, build, installation and commissioning of a fully modularised 84MLD ceramic membrane plant at Alderney Water Treatment Works (WTW).

The Bournemouth supply area is reliant on two strategic WTWs, Alderney WTW which supplies coastal Bournemouth and a wide area of East Dorset, and Knapp Mill WTW which supplies Christchurch and areas of the New Forest.

Alderney WTW is located near Bournemouth and will have capacity to produce 82 million litres of high-quality water to the catchment area. Further to the Alderney WTW project awarded to RSE in April 2023, RSE is also currently engaged by SWW to provide the sister plant Knapp Mill WTW as an effective carbon copy of the project, yielding significant programme and cost savings to the client through repeatable standard design packages.

The RSE scope is being provided as a fully modularised off-site build plant, with principal contractor Kier undertaking the balance of the site works. The membrane plant will be unique in its design due to the inclusion of Ozone (03) dosing into the main process stream. Ozone is a powerful oxidising agent which dissolves in water to produce a biocide that destroys harmful bacteria, algae and biofilms. The addition of Ozone facilitates vastly improved ceramic membrane performance, increasing operational flux limits and providing a self-cleaning membrane process. This has the added benefit of reducing the amount of chemically enhanced backwashes required specifically the removal of the Alkali wash requirement.

The project will add an additional filtration stage to the process, install 10. No ceramic membrane filters, complete with ancillary equipment required for backwashing and chemical cleaning. SWW are future proofing the plant, and customer supply, by including provision for the future installation of a further 2. No ceramic membrane filters.

The new PWNT ceramic membrane process is being installed downstream of the existing Slow Sand Filters (SSF) and upstream of the Granular Activated Carbon (GAC) filters to provide a barrier. The RSE Design team are working in collaboration with SWW and Kier to look in fine detail at all parts of the process, including the hydraulics and controls to ensure the new process is integrated seamlessly and within the time and cost constraints of the project.

With RSE teams delivering a fully modularised project designed and constructed off-site in our state-of-the-art fabrication facilities, this allows the design and delivery teams to be empowered to employ the use of the innovative technologies, taking cognisance of current market conditions to achieve best programme, CAPEX/OPEX, quality and environmental outputs. This approach to delivery removes traditional governance and management costs, improves carbon reduction, and returns significant programme duration and cost reductions in comparison to traditional design and build methods.

As part of the package supply, RSE is integrating a modularised off-site build Ozone Generation, Dosing & Destruction package from Nijhuis as appointed by SWW. RSE will additionally be responsible for adding further chemical delivery, handling, storage, and dosing for 3 No. additional treatment chemicals required as part of the membrane cleaning and Ozone quenching process. In order to unlock savings for the wider project, RSE has recently incorporated downstream sulphuric acid pH correction bulk storage and dosing in the package plant offering.

Once installation is complete, RSE will embark on a phased commissioning strategy ensuring that the commissioning process is completed while minimising the interfaces and risk to the existing works, which must always remain in service. Due to the large volumes of water required to commission the ceramic membrane filters re-use of the commissioning water is being considered to help minimise the impacts of the commissioning process. The commissioning strategy is being developed in collaboration with SWW’s Operations team to ensure its success.

RSE teams are currently in a detailed design phase which is feeding directly into our Production facilities, since the off-site modular build has commenced, and the procurement of all long lead time items progressed to secure best programme for SWW. All modular buildings and internals will be progressed over the coming months ready to accept the PWNT ceramic membrane vessels for off-site testing and commissioning ahead of our scheduled delivery dates.

Ceramic membranes are an innovative technology that are transforming how the water sector will filter water now and into the future. At RSE, we pride ourselves on being at forefront of innovative water treatment and water recycling technologies which support the sustainable and secure growth of the UK economy.

The Alderney WTW project is part of SWW’s current investment upgrade programme, designed to develop existing water treatment sites to continually improve water quality for customers across the region. The construction, installation, and commissioning phases of the RSE ceramic membrane package plant for Alderney WTW is due to be completed in early 2025.