Southern Water has approved the purchase of two phosphorus filtration units following a successful trial at its Storrington wastewater treatment works in Sussex.
The units, supplied by Marlowe Environmental Services, use Flocell XFM filtration technology to enhance tertiary treatment performance and support compliance with tightening environmental standards.
The equipment was initially installed on a hire basis in June 2025. Following the successful trial period, Southern Water approved the units for permanent operation at the site.
The two Flocell XFM20 filtration units contain four modular filters and can collectively treat flows of up to 40 litres per second.
Phosphorus removal technology trial at Storrington
The containerised filtration system was installed without the need for additional civil engineering works, allowing it to be deployed quickly within the existing treatment infrastructure.
The system supports tertiary treatment at the Storrington wastewater treatment works, which serves a population equivalent of around 8,000.
By enhancing the existing treatment process, the system enables the site to consistently achieve a phosphorus consent level of 0.5 mg/litre, alongside permits for biological oxygen demand, total suspended solids, iron and ammonia.
Connor Sandalls, senior processing engineer at Southern Water, said the technology was first identified during industry discussions at the European Wastewater Management Conference.
He explained that the units were initially hired to evaluate their performance before being approved as one of the treatment options available for use across Southern Water wastewater treatment sites.
Increasing pressure to reduce phosphorus discharges
Water companies across England and Wales are facing increasing regulatory requirements to reduce phosphorus levels discharged into rivers and other water bodies.
The Environment Act 2021 includes targets requiring an 80 percent reduction in phosphorus discharges from treated wastewater by 2038.
Some wastewater treatment plants now operate under permits as low as 0.25 mg/litre phosphorus, requiring utilities to adopt new treatment technologies to meet tightening limits.
Flocell XFM filtration technology is designed to remove tertiary solids and phosphorus using an open-cell filtration media that retains particulates while maintaining stable flow rates.
The units can operate under pumped or gravity flow and can be deployed inline within treatment systems or used in dialysis flow configurations.
According to Marlowe Environmental Services, the filtration system can operate for extended periods without backwash and uses air agitation to clean the media during short maintenance cycles.
This design helps reduce energy consumption and eliminates the need for large volumes of process water typically required for conventional backwashing systems.
The system can also be scaled by connecting multiple units in series, allowing utilities to adapt treatment capacity as flow requirements increase or environmental permits tighten.
