Sustainable Plastics - September/October 2023 - 24

contamination study
continued from page 23
science-based exploration to
close the loop on post-consumer
food-grade PP.
Achieving this has required
addressing each and every
roadblock along the way and
deep-diving into the specific
sorting and decontamination requirements
for the recycling processes
for PP. This has led to our
most recent investigations to determine
the residual contamination
levels of post-consumer PP
packaging, which, up until now,
have not been characterised.
The lack of data showing the
misuse rate within PP feedstocks
has meant there was
no reliable way of defining the
residual levels that could potentially
migrate into food as well
as understanding which molecules
to target via decontamination
processes.
Nextek's study aimed to
identify substances that might
cause samples to be outliers
from the expected input stream
which could represent challenges
to the final safety of the
recycled plastics. The key was
to check whether the substances
observed could potentially
be genotoxic. This is a critical
criterium for European Foaod
Safety Authority evaluations
given that the substance could
be derived from the mis-selection
of an item of non-food PP
packaging, which is not necessarily
a case of misuse.
Although, being olefinic, PP
has very similar properties to
HDPE, the packaging format
of PP reduces the chances of
it being in a consumer-misuse
scenario. A large proportion
of PET packaging is relatively
durable, with a tight closure,
making it a container of choice
when used for the storage of
hazardous materials.
Likewise, HDPE packaging
is also in bottle form with
a closure, meaning it, too, may
be used in such a scenario. PP
food containers, on the other
hand, are less likely to come in
bottle form and much more likely
to be pots, tubs or trays with
limited closure capability.
Characterising the residues
in post-consumer packaging
that have been sorted into monopolymer
fractions was done
by analysing and testing multiple
batches of food/non-food
24
Paul Marshall
samples to see what molecules
are present and whether there
are any areas of concern.
To achieve this, Nextek's
team of scientists worked on
a 20-tonne batch of PP bales
sourced from a UK-based materials
recovery facility. Using
automatic optical sorters to separate
colour fractions of natural
(clear), white and coloured articles,
each colour fraction was
hand-sorted into articles from
food applications and articles
from non-food applications.
The analytical study involved
700 tests, which represented
approximately 17,500 different
PP packs based on 25
significantly sized flakes per
test. This was estimated to be
a cross-sectional representation
of 7% of the packs from
the combination of batches of
260,000 packs.
Following this contamination
study, Nextek characterised the
contamination levels in PP and
concluded that they are in the
order of 10x less than what we
expect in HDPE milk bottles and
100x less than expected in PET.
These results further validate
Nextek's global multi-participant
project, NextLoopp, as it
breaks through the final barriers
to closing the loop on foodgrade
recycled PP.
By deploying innovative
technology to effectively sort
post-consumer PP packaging,
the project is now harnessing
these study findings to fasttrack
the production of INRT-grade
and food-grade rPP.
The growing need to recycle
post-consumer PP packaging
into a suitable material for primary
food-contact packaging is
driven by the European Union
policy to include at least 10%
recycled content for all packaging,
increasing to 50% by 2040.
Understanding the sorting
September/October 2023
NextLoopp in brief
Although a commonly used
packaging material for food
across the globe - unlike,
for example, PET bottles -
post-consumer PP packaging
is not widely recycled
in conventional mechanical
recycling infrastructure.
One reason for this is that
mechanical recyclers have,
up until now, not been able
to differentiate between PP
bottles that once contained
chemical products from
those containing food. As a
consequence, current foodgrade
recycled PP is currently
limited to advanced recycling
technology processes.
The NextLoopp project,
initiated and led by sustainability
consultancy Nextek, is
a two-year, multi-participant
project aimed at closing the
loop on food-grade rPP. The
project uses a combination
of technologies to first separate
food-grade PP from the
rest and then decontaminate
the polymer. Sophisticated
and decontamination requirements
needed to enhance the
recycling processes is a major
step towards achieving this.
More importantly, this data
is essential towards enabling
food-grade PP packaging to be
recycled into high-value recyclates
that can safely be used
in new food-contact packaging,
and this takes us back to the climate
change debate.
Back to UNEP's draft global
plastics treaty, it would be beneficial
to scientifically model the
impact of adopting the various
options to gain a clearer understanding
of which steps will have
the greatest impact on the current
direction of plastic waste.
In my opinion, we must flip
our perspective on recycling.
If we are to simultaneously reduce
our waste and our reliance
on virgin resources, then
we must pivot from recycling
to re-looping. In other words,
we must focus on turning used
products back into equal-value
products. Instead of recycling
plastic packaging to achieve
commodity resins, we should
re-loop plastic packaging into
the highest-quality resins posProfessor
Edward Kosior
sible. Our recent study now
gives us the leverage to work
towards this.
Professor Edward Kosior set up
Nextek Ltd. in London in 2005 as
the inaugural managing director.
He is an Honorary Professor at
Brunel University London, at the
Wolfson Materials Processing
Centre. He is a Fellow of The
Society of Plastics Engineers
(FSPE), Fellow of the Institute of
Materials, Minerals and Mining
(FMMM), and a Fellow of Royal
Society for the Encouragement
of Arts, Manufactures and Commerce
(FRSA). Kosior launched
the NextLoopp project in 2021.
decontamination technology
is used in combination with
an innovative, commercially-proven
fluorescent marker
sorting technology called
PolyPrism. PolyPrism applies
high-performing luminescent
materials to labels on plastic
packaging, creating an invisible
'barcode' for plastics recycling.
When applied to foodgrade
packaging labels, these
UV-fluorescent markers can
be used to sort food from nonfood
packaging. The markers
can be removed during recycling,
leaving no traces for the
next cycle of use.
The goal of the project is
to validate the process developed
to manufacture foodgrade
recycled polypropylene
and its commercial viability, in
order to receive acceptance
from the UK's Food Standard
Agency and European equivalent,
EFSA. A consortium of
companies from across the
value chain are taking part on
the project.
Sustainable Plastics - September/October 2023

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