Sludge held on sludge piles is naturally dewatered and converted into compost.

The planted reedbeds grow roots and a thick mat of rootlets called rhizomes that act as a bio-pump to facilitate air and water transfers in the filter bed and sludges.
As the reedbed establishes uniformly, the filter steadily declogs itself—naturally. The sludge dries out and mineralizes.
Down in the root zone, a water-purifying biotic symbiosis establishes between the plant and the organisms at the root/biofilm interface.

The plant transfers oxygen down to its root system, where it fuels thriving microbial activity, and in return uptakes nitrogen and phosphorus as nutrients.
Plant-driven evapotranspiration and percolation are the main drivers of natural sludge dewatering.