PAPER TECHNOLOGY INTERNATIONAL - Sorting for a circular future: How new technologies unlock new opportunities in paper-based packaging recycling. Susanne Haase, Program Director, 4evergreen - Paper Technology International 2026 - Book - Page 109

PAPER TECHNOLOGY INTERNATIONAL - Sorting for a circular future: How new technologies unlock new opportunities in paper-based packaging recycling. Susanne Haase, Program Director, 4evergreen

PAPERTECHNOLOGYINTERNATIONAL
A Fragmented System in Need of Harmonisation
Materials recovery facilities (MRFs) across Europe are
equipped with a wide mix of technologies, from mechanical screens
to sophisticated optical sorters. While these tools can handle most
conventional paper packaging, challenges can start when packaging
contains components that are hard to handle in widely used paper
recycling processes or other disruptors:
•
Integrated plastic windows confuse the optical
signature.
•
Thick outer coatings can conceal the 昀椀bre-based
substrate underneath.
•
Carbon-black pigments absorb NIR (near infra-red
light), making objects “invisible” to scanners.
•
Metallised surfaces scatter near-infrared (NIR) signals,
making identi昀椀cation dif昀椀cult.
As a result, these items may be wrongly sorted, rejected, or
diverted to lower-value streams. Once they miss the correct path,
they rarely return.
What’s missing, according to industry experts, is a
harmonised, Europe-wide sorting protocol – an area where
standardisation discussions are currently underway at European
level.
In practice, each technology provider and sorting facility
applies its own tests and thresholds. For packaging designers, this
makes it complex to predict real-world recyclability.
The Technologies Powering Today’s Sorting
1. Mechanical Treatment: The First Gatekeeper
Before sensors, algorithms, or air jets come into play, waste
昀椀rst passes through a series of mechanical “gatekeepers.” Rotating
trommels, screens, and ballistic separators loosen compacted
material and sort it by size and shape. This step may seem purely
preparatory, but it already shapes the recycling outcome: what is
separated out here will never reach more advanced sorting stages.
Most paper-based composites end up in the mid-sized
fractions – typically between 50 and 220 mm – that are then sent
forward for optical analysis. If materials are misdirected at this
early stage, even the most advanced downstream technology can’t
recover them.
2. Optical Sorting with NIR–VIS Systems
Once materials reach the optical line, near-infrared and
visible-light systems take over. These NIR-VIS (near-infrared visible)
sorters are the backbone of modern facilities, identifying materials
based on how they re昀氀ect and absorb light rather than how they look
to the human eye.
They perform reliably with
well-established paper streams such as:
• graphic papers,
• corrugated board
• liquid packaging cartons, whose
distinctive 昀椀bre-plus-polymer structure
makes them relatively easy to recognise
The challenge emerges as
packaging formats diversify: Multilayer
structures, coatings, foils, and
unconventional shapes can blur optical
signals or mimic other materials. As a
result, optical sorting can no longer carry
the system on its own.
109

Paperturn flipbook viewer