Sustainable Plastics - October 2021 - 32

recycling
continued from page 31
ered to be recycling processes
in the EU.
Generally speaking, however,
most people tend to simply
divide plastics recycling more
broadly into mechanical and
non-mechanical processes.
Mechanical recycling
Mechanical recycling is a multistep
process involving the collection
and sorting of post-industrial
and post-consumer
waste plastics after which these
are milled or shredded, washed,
separated and extruded into regranulate.
Mechanical recycling
operations include equipment
such as milling machines, shredders,
washing drums, flotation
separators, centrifuges and tumble
dryers. Regranulating and
compounding lines process the
output into recycled resin.
An advantage of mechanical
recycling is the fact that
the molecular structure of the
plastics remains intact, which
means the energy, initially input
to produce the plastic, is preserved.
Especially in the case
of clean, waste streams consisting
of a single type of plastic,
it offers an excellent solution.
As PlasticsEurope writes: 'the
environmental benefits from
substituting virgin material generally
exceed the environmental
burden from collection, sorting,
transport and recycling operations,
while the costs of such
operations can be outweighed
by potential revenues from selling
recyclates on the market'.
However, there are disadvantages
as well: in the first place,
mechanical recycling cannot
handle mixed or contaminated
waste; second, mechano-oxidative
and thermo-oxidative
mechanisms occur which affect
the molecular weight, molecular
weight distribution, crystallinity
and chain flexibility of the polymers,
leading to degradation.
Yet, huge strides are being made
to improve the mechanical recycling
process, to increase its efficiency,
yield and output quality.
Initiatives, such as the HolyGrail
2.0, where the use of digital watermarks
is being tested for precise
and accurate sorting, have
been launched; the use of optical
spectroscopy has become more
widespread; extruders are avail32
2020
able
that are tailored for recycled
materials, with degassing sections
which allow release of volatile
compounds in the melt and
filters to remove large contaminants.
Sophisticated automatic,
self-cleaning melt filters enhance
melt quality and throughput
speed, while antioxidants, chain
extenders, compatibilisers and
others have been developed to
produce recycled compounds
suitable even for higher-end applications.
Non-mechanical
or
advanced recycling
Non-mechanical or advanced
recycling has generated a huge
amount of interest in the past 3
or so years. Rather than just one,
there are a variety of advanced
recycling technologies, ranging
from selective dissolution to
depolymerisation and pyrolysis.
These processes offer a number
of distinct advantages, the most
important of which is their ability
in most cases to handle mixed,
'unrecyclable' waste, although
technologies are also being developed
to handle one type of
waste, i.e., PP or PS. They deliver
significant quantities of recycled
material with virgin plastic
properties, enabling the recyclate
to be increasingly used in
sensitive applications, such as
for food contact. Yet advanced
recycling, although it looks
promising, still has to take off in
a big way. Rabobank published
a report in March 2021, entitled
What does advanced recycling
have in store? in which it identified
some of the most important
issues confronting the further
advancement of these technologies.
At the top of the list are
cost and feasibility: advanced
recycling pants require major
investments in technologies
that often still must be proven at
commercial scale. This constitutes
a risk that investors are not
always prepared to take. Another
issue is the environmental aspect.
Uncertainties persist about
the potential toxicity and carbon
footprint of these technologies;
in addition, where these plants
are focussed on turning plastic
waste into fuel, rather than into
feedstock for new plastics, this
is often seen as being incineration
in disguise. The Rabobank
report further pointed to the
Recyclers/Waste
management
companies
* Indaver
* Remondis
* Ravago
* Suez
Plastic feedstock
suppliers
* BASF
* Borealis
* Dow
* Dupont Teijan Films
* Eastman
* Indorama
* INEOS Styolution
* LyondellBasell
* SACIC
* Trinseo
* Toyo Styrene
Oil/fuel
companies
* BP Infinia
* Neste
* Shell
* Total
Plastic packaging
converters
* Mondi
* Plastipak
* Sealed Air
* Südpack
* Logoplaste
* Toyo Seikan
Group Holdings
* Hokkai Can Co. Ltd.
* Yoshino Kogyosho
* Scholle IPN
* Greiner Packaging
* Berry Global
Source: Rabobank 2021. Selected petrochemical supply chain players in
advanced recycling.
competitive pressure from the
increasingly sophisticated improvements
in mechanical recycling
technology; the traceability
and certification aspects; and
the possible effects of legislation
and policy.
In that context, it is worth noting
that the current deluge of
'certified circular' materials produced
by a growing number of
raw material producers are for
the most part not yet officially
regarded as recycled materials.
While derived from feedstock
produced through advanced recycling,
most types of advanced
recycling are not yet recognised
as recycling.
The future: not one or
the other
Increasingly, however, as the
push to transition to a more circular
economy gains strength,
accompanied by the need to
vastly improve recycling rates,
the industry would seem to
be stepping away from an 'either-or'
stance, and moving
towards a model where there
is room for both advanced and
mechanical recycling. Cascade
recycling, as this is known, is
the only solution that will enable
the ambitious recycling targets
and pledges of the EU to be
met, say industry experts. Also,
pre-consumer waste must be
recognised as equally contributing
to recycled content targets,
which is currently not the case.
To scale up chemical and mechanical
recycling, companies
will need to have access to all
plastics wastes i.e., pre-consumer
and post-consumer waste.
A company that is already exploring
this model is polyolefins
producer Borealis. For example,
the company cquired
in July 2021 a 10% equity stake
in a Belgium-based recycling
company called Renasci, which
is in the process of patenting
a concept called Smart Chain
Processing (SCP). That concept
involves a proprietary method
of maximising material recovery
in order to achieve zero waste,
through the processing of multiple
waste streams using different
recycling technologies - all
under one roof. At the Renasci
SCP facility in Oostende, Belgium,
mixed waste - plastics,
metals, and biomass - is automatically
selected and sorted
multiple times. After sorting,
the plastic waste is first mechanically
recycled, and then
in a second step any remaining
material is chemically recycled
into circular pyrolysis oil
and lighter product fractions.
" Our approach to circularity -
continued on page 34
Sustainable Plastics - October 2021

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