Plant-Based Solutions

Planted Reed Drying Beds (PRDB)

The reeds are planted on the surface of the bed, which they densely cover. They develop a network of roots, similar to a drainage system, that spreads during the steady accumulation of sludge across the layer height (usually, more than a meter). The dissolved matter decomposes due to the biomass of aerobic bacteria on the filter medium as well as on the settled bed that accumulates on the surface. The beds must be cleared of excess dry and mineralized sludge every 5 to 8 years.

The core principal behind sizing is the annual loading rate of Dry Matter per m2 the system can handle.
The drying beds are usually divided into compartments to distribute the drainage and give the bed time to dry.

The drying process in planted reed beds consumes very little energy and transforms sludge into moist soil (15% to 35% dry solid material) that is easy to transport, compost, and store on agricultural headlands.

PRDB_TECHSHEET.pdf

(SRC) Short Rotation Coppice

The SRC is a planted area usually featuring selected species of willows kept growing by one harvest every 2 to 3 years. They are fed in a controlled way by a microirrigation network to take advantage of the willows’ evapotranspiration capabilities and nutrient requirements.

Soil particles filter used water and suspend elements. Macro and microorganisms in the soil transform and stabilize nutrients (nitrate, phosphate, potassium, etc.) Willows, a fast-growing plant, absorb these elements to grow.

Key figures for SRC in France today: