ARM, in collaboration with Galliford Try, was thrilled to receive the prestigious Green Apple Gold Award in November 2023 at the Palace of Westminster.
The award recognized the innovative ARMPhos™ phosphate treatment system implemented at the South West Water Wilmington sewage treatment works. This system offers an alternative to traditional chemical/ferric dosing methods by using a reactive media to reduce phosphorus discharge levels.
The Green Apple Award judges praised the collaboration, noting that the ARMPhos™ system is the first of its kind in the UK. Installed at an existing sewage treatment plant, it significantly reduces phosphorus levels while enhancing the ecological environment. The system is now being considered for larger-scale applications due to its ability to lower chemical usage, costs, and carbon emissions.
ARM Ltd was contracted by South West Water to design and construct the ARMPhos™ filter, which reduces phosphate levels in wastewater to meet new Environment Agency targets. The system treats 40% of the water flow through a reactive media bed, while the remaining 60% bypasses the filter and is then remixed. To prevent flooding, the filter bed's perimeter was raised by 930mm, creating a protective barrier.
The ARMPhos™ system uses apatite-based reactive media to remove phosphate through adsorption and crystallization. Initially, phosphate ions are captured by the apatite, which contains naturally occurring cations like aluminium and iron. Once these binding sites are saturated, phosphate crystallizes, forming calcium/phosphate crystals in the solution, which can be physically extracted from the bed. While the adsorption phase has a finite duration, crystallisation can continue indefinitely. With proper design and installation, the system can operate for 10-15 years before needing refurbishment.
