Constructed wetlands act as filters for organic matter, trapping it within the matrix of the bed. After a number of years this leads to the reed bed to clog up leading to a reduction in treatment efficiency.
How fast a reed bed clogs up varies from site to site and depends on the operating conditions, previous maintenance regimes and effluent characteristics. Reed beds that have not had a maintenance regime, or those treating effluents with high organic matter, will have a reduced working life.
Through refurbishing the reed bed and replacing the clogged media, it can return it to its optimal treatment efficiency. Previous refurbishments of a reed bed involved the removal of clogged media which would then be sent to a landfill site – a costly, wasteful and unsustainable process.
Following a Knowledge Transfer Partnership (KTP) with Harper Adams University College, the Aggregate Recycling Machine was created to enable the media to be washed on site, recycled and returned to the same reed bed. This process lowers lifetime running costs, extends the life of the bed and reduces the need for new gravel – a great example of ARM innovation at work.The Aggregate Recycling Machine will clean most aggregate and can therefore be used for cleaning media in Biofilters.