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Phragmifiltre® is the first reedbed technology in the UK that provides complete treatment of macerated or raw sewage in a single wetland system, with no pre-settlement and little or no power requirement.
To date there are over 800 Phragmifiltre® systems treating raw non-settled sewage from 20 to 5,000 PE (population equivalents) throughout Europe. The first UK system was completed in September 2015.
Developed in France, the Phragmifiltre® requires only screening and / or maceration of raw sewage, with no pre-settlement.
The system is typically designed to have two stages.
The first stage is designed to filter, using three or more beds, and de-water the solids from the raw sewage on the surface of the reedbed. Macerated / screened sewage is fed to each bed in rotation, allowing all the beds to have a rest period. The filtrate passes down through the beds, which act as a typical vertical flow reedbed, primarily reducing BOD but also undertaking nitrification of ammonia.
The second stage, comprising vertical flow reedbeds, provides additional BOD reduction and completes the nitrification of ammonia prior to discharge.
Siphon technology is used (where possible) for dosing at both stages, minimising power requirements.
Phragmifiltre® stores and composts sludge on site, unlike conventional sewage treatment works, which generate sludges that have to be taken from small rural works for treatment. Phragmifiltre® only requires monthly operator visits. The mineralised sludge accumulated on the first stage beds should be removed once every 10-15 years and can be applied to land, since it meets “enhanced treated product” status.
Performance data from 70 plants have shown mean removal efficiencies of: