A test for biodegradability aims
to show that resources or products like for instance plastic film, bags, forks
or packages are biodegraded during a specified time and to a high percentage.
The biodegradation is performed by microorganisms in either water or in
Biodegradable materials are
investigated for degree of degradation, rate of degradation and other effects
of the products on the environment
6.1 Test program
A complete test program for compost
ability according to EN 13432 therefore consists of four parts:
The first step consists of characterisation
of the material. Components that are potentially dangerous to the environment
or important for the biological treatment are analysed; for example heavy
metals, carbon/hydrogen/nitrogen contents and identification of polymers and
two constitutes a test for the ultimate degree of biodegradability of the
material during optimal conditions according to one of the following methods in
which the amount of carbon dioxide produced is measured:
– aerobic (with oxygen) aquatic biodegradation according to e.g. ISO
– aerobic small scale composting according to e.g. ISO 14855.
The biodegradability tests can be completed with determinations of biomass and
three is a disintegration test. A control is made to ensure that the
material/product is disintegrated into small fragments not possible to sieve
through a 2 mm sieve. Industrially compostable waste is tested according to ISO
20200 or ISO 16929. Small scale (home) compostable waste is tested according to
SP method 4148.
step four the compost derived from the disintegration test is composted to
maturity. After that, its effect on water- or soil-living organisms is analysed
in Eco toxicological tests. The tests can be performed on higher plants
according to OECD guideline 208 + annex E in EN 13432.
Of course it is fully possible to
test according to only parts of this test program. Analysis of toxic compounds
is performed by Chemical Analysis.
Today some certification systems
for industrially compostable plastics exist in different countries. These
different systems mainly contain the same test methods and criteria but use
different certification labels. SP has developed its´ own certification system
that in addition also includes other types of waste treatment.