Waste smaller than 70 millimetres produced by the residual waste separation plant is considered to be an organic wet fraction (OWF). This source is often sold directly to a digester for green gas. That said, OWF also contains other valuable raw materials, or inert streams, which this plant extracts. For instance, 3% of OWF is synthetic material.
Moisture accounts for 50% of OWF. Most of this moisture is in fractions smaller than 6 to 8 mm. This fraction can be separated using a sieve. The gas yield in fractions smaller than 6 to 8 mm is low. Drying this fraction reduces the mass by 50%. It is possible to recycle this fraction even more.
The 6 to 70 mm fraction contains a lot of deformable 2D materials. Wind shifting separates foils and paper from 3D materials, like plastic, wood, stone, glass, metals and non-ferrous material. After removing the iron from 3D materials using magnets, the plastic is separated using near-infrared NIR scanners.
What remains is passed through an X-tract, a radiation machine that uses X-ray and infrared technology to recognise types of waste down to the molecular level. Stone and glass are extracted on the basis of permeability. The organic fraction residue can be sent to the digester, where it produces a high gas yield.
The stone fraction can be used as raw materials. The glass is produced with a purity of more than 95% and is suitable as raw material for the glass processing industry.
The OWF separation plant can be designed and built according to customer specifications, with a processing capacity ranging between 5 t/hour to 40 t/hour.
