issue 01/2022

Basics
but also due to their functional use in these environments
(think about horticultural aids, fertilizer coatings, fishing
nets, etc.). Several specific test methods exist to assess
degradability of materials in these uncontrolled environments.
Recently, new test methods have been developed to assess
biodegradability in marine water habitats. The sea is a very
diverse environment with many different habitats, like the
open water, seawater/sediment interface, or the marine
sediment, and there is still a lot of research to be done here.
A standard specification with pass/fail criteria on
biodegradability of products intentionally used on and in
soil did not exist until 2018, at which point EN 17033 (2018)
for biodegradable mulch films was published. Aside from
biodegradability in soil, additional requirements linked to
heavy metals & toxicity are included.
Long-term biodegradation, an opportunity?
Certain products should biodegrade within a short
timeframe as these materials have a short functional life
(e.g., detergents) or as these materials often only spend a
limited time in the processing facility (e.g., food service ware)
like a composting plant or anaerobic digester. The main focus
of current certificates is also on these ready biodegradable
products.
However, ready biodegradability is not always the best
option since certain materials first need to fulfil their (long)
functional life in the environment before biodegrading. This
offers a whole new range of challenges and opportunities
for producers. Examples of such materials can be found
in horticulture. Mulch films should have good mechanical
properties over their operational lifetime (one or multiple
seasons) and the degradation process should only start when
mulch films are ploughed into the soil. Another example from
horticulture is slow-release fertilizers. These polymers should
continuously degrade over a long period of time to guarantee
continuous release of the fertilizer. Also in pisciculture, there
are materials that end up in the ocean and cannot be easily
retrieved. For these materials in situ biodegradation in soil/
water offers an added value.
Day-to-day products like textiles, shoe soles or car tires are
another source of unintentionally dispersed microplastics.
Although these products should not be marketed as
biodegradable, it would be beneficial if these materials
degrade over time and would be non-persistent. For these
types of materials, long-term biodegradation and thus nonpersistency
has an added value.
However, biodegradability should never be used as a license
to litter. Therefore, a distinction should be made between
biodegradability as an inherent product characteristic that can
be communicated on a business-to-business or a businessto-government
level and biodegradability as an end-of-life
option that can be communicated to the public. For example,
it is beneficial if cigarette filters are biodegradable, although
they should not be marketed as such as to not encourage
littering. In a lot of regions, it is therefore also prohibited to
market products as biodegradable.
In summary
If we want to tackle the plastics waste problem, a systemic
approach with regard to waste will be needed. Products
should be designed for reusability & recyclability, however,
for certain applications including highly contaminated waste
like food service ware and coffee capsules, this is not always
possible. In such cases, organic recycling (biodegradation)
is a good alternative. Clear communication between
legislators, producers, consumers, and waste operating
facilities is vital to ensure proper waste management.
Biodegradability is highly dependent on the environment
as it is linked to the activity of different types of microorganisms
present. It is important to select the
environment in which to test the biodegradability based
on the foreseen end-of-life of the product. Managed
end-of-life options include composting and anaerobic
digestion. Unmanaged end-of-life environments include
soil, fresh water, and marine water. Products leaking into
uncontrolled environments should not necessarily be ready
biodegradable, although non-persistency for these types of
products is all the more important.
About the authors
This article was written by Bruno De Wilde (Managing
Director of OWS), Astrid Van Houtte & Tristan Houtteman
(both Marketing & Sales Engineers at OWS). OWS is a
strictly independent testing laboratory and has over 30
years of experience in the field of biodegradability and
compostability testing, for which it is certified & accredited
to ISO 17025. OWS is the only laboratory worldwide that
is recognized by all certification bodies active in the field
of biodegradability and compostability: TÜV AUSTRIA
(Belgium), DIN CERTCO (Germany), BPI (US), JBPA (Japan)
and ABA (Australia). Furthermore, OWS is a (very) active
member of several normalization organizations such as
ISO (international), CEN (European) and ASTM (US) and
is the official Belgian delegate of several ISO and CEN
committees. For more information about OWS, you can visit
their website.
www.ows.be
52 bioplastics MAGAZINE [01/22] Vol. 17