Arcadis has been working with South West Water on the Mayflower Water Treatment Works since the initial concept stage some five years ago. As well as the construction of the WTW, the project included the laying of 7km of new pipeline to connect the site with the existing distribution network.
The project incorporates ground breaking membrane and ion exchange technology in clean water treatment, which is unlike conventional process used around the world. The process stream includes raw water screening to 1mm, suspended ion exchange and inline coagulation followed by membrane filtration, granular activated carbon (GAC) and UV final treatment to ensure a complete deactivation of viruses.
Ceramac membrane filtration can be described as an absolute barrier within the treatment process. The membrane pore size is one ten thousandth of a millimetre, so it can remove bacteria as well as viruses such as cryptosporidium and giardia.
Following this stage, the membrane permeate (treated water) enters the more conventional GAC plant to address potential tastes and odour in the water and remove residual pesticides.
Most surface water treatment works in the UK use a chlorine-based disinfection process. UV offers a safe and robust method of disinfection and negates the risks of handling and transporting potentially dangerous chemicals.
It is the first time that this combined technology has been used in the UK. This is a significant innovation in surface water treatment. Policies such as ‘all under one roof’ and ‘lean maintenance’ were adhered to throughout to create a working environment suitable for the 21st century.
Arcadis is the overall design consultant responsible for the design of the plant, working in collaboration with a number of stakeholders including the membrane technology suppliers. Arcadis carried out the full range of design development and delivery, including mechanical, electrical, controls, civil and building works. All the deliverables were created digitally within the BIM environment.
Models were regularly updated and used to demonstrate to the client the design and operation of the plant. Techniques such as clash detection, video and walk throughs were used. Collaboration with the supply chain was essential to assist with the integration of all elements of this compact water treatment works.