Introducing the biodegradable bag into Switzerland's organic waste collection
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Landfill gas is a major source of global warming if it is
vented into the atmosphere. However, a growing market
in carbon credits means there are very strong incentives
to develop landfill gas-to-electricity projects, and, using
updated inputs to existing computer projections, their
technical feasibility can be assessed. Taking into account
local variations and conditions, these projections can
predict the amount of gas that will be produced over a
landfill's lifetime, providing a valuable source of data.
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René Estermann |
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The five or six years leading up to the use of
biodegradable (BDM) bags for organic waste
collection in Switzerland has been a time of numerous
tests, shared practical experiences, consultation about
certification and labelling, and a lot of communication
between all the interested parties.
An extended study tested six products in 1997-8.
Although these bags proved to be suitable, there were
provisos: they needed improved stability, replacement of
dyes which contained heavy metals, guarantees of
biodegradability according to an international norm, and
the use of a uniform mark, so BDM bags could be
distinguished from conventional plastic ones. Under the
mandate of the Swiss Agency of Environment, Forest and
Landscape (SAEFL), a project group made up of
representatives of all concerned parties worked together
to produce guidelines for BDM bags sold in Switzerland.
The bags have to fulfil the requirements of the DIN EN
13432 (testing of compostability of plastics) and must be
uniformly marked with a white grid.
Since May 1999, sales of the bags across
Switzerland have exceeded expectations.
Consumers use them as liners in compost
buckets and containers. A handful of
composting and digestion facilities refused the
BDM bags to begin with, worried about
degradability and a possible increase of
foreign materials in the compost when the
bags were used. But since the bags have
proved themselves in daily use, opposition has
faded, and BDM bags are now generally
accepted. An increasing number of communities and
composting facilities promote them actively for more
convenient and hygienic collection of organic waste. Other
kinds of BDM plastic film will now be introduced
for packaging applications, with the same requirements of
the DIN EN 13432, and the white grid mark.
Organic waste management in Switzerland
According to SAEFL statistics, about 250 professional
composting or fermentation facilities in Switzerland
process around 700,000 tonnes of biological waste each
year. Half of this waste comes from communal separate
organic waste collections, and half is delivered to the
facilities directly. The amount of organic waste going to
garbage incinerators is estimated to be about 500,000
tonnes.1 The amount processed privately in gardens,
housing estates and public facilities and companies (so-called
local, decentralized composting) is estimated to be
about 300,000-400,000 tonnes. Due to the federal
structure, there are many different composting
arrangements and systems. |
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BDM packaging for carrots and potatoes
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Prior to 1997, several manufacturers of
compostable, biodegradable bags had put
their products on the Swiss market. It was
anticipated that various types of BDM bags for
collection of organic waste would soon to be
launched by wholesalers. In addition, some
communities were considering the use of
BDM bags for the collection of their organic
waste, although waste processing and collection facilities
greeted the idea of such bags with little enthusiasm and
many questions.
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Practical testing of BDM bags
In 1998, a number of different BDM bags were tested
among consumers, private composting groups and
community collectors, as well as under laboratory
conditions. The intention was to find answers to the
following questions:
- Do the bags fulfil present evaluation standards of
compostability?
- How quickly do the bags decompose at professional
composting facilities or in private or communal
composting facilities?
- What is the influence on processing in the
composting facilities?
- Is the quality of the compost impaired?
- Do the bags prove themselves in household use -
what are the advantages and disadvantages for the
consumer?
- What are the changes for garbage collectors?
- Do the bags lead to disposal of foreign matter with
organic waste?
- How great is the environmental stress due to BDM
bags, as opposed to that which is due to conventional
collection methods (green bucket, containers with and
without liners)?
The information gathered over the course of the test period is
summarized below.
Consumers
It was established that there was a demand on the part of
the consumer for BDM bags for organic
waste collection. When questioned, one
half to two thirds of households
expressed a willingness to buy such bags.
Positive adjectives used to describe them
included 'clean', 'practical', 'hygienic' and
'compostable'. Negative adjectives used
were 'leaky' and 'costly'.
Private composting
Most of the BDM bags examined in the
test for organic waste did prove
themselves in private use. They involved
little additional care in the way of
compost management and decomposed
within the usual decomposition period.
Two thirds of the compost groups
questioned said that they would allow the
use of BDM bags on their compost heaps;
one third would not.
Community collection
During the test period, organic waste
collection with BDM bags did not lead to
an increase in foreign matter (see Table 1). This was
confirmed after the bags were tested over a period of one
year in Lucerne, a town of 60,000 inhabitants.
TABLE 1. Amount of foreign matter in organic waste collection with and without BDM bags (%) |
|
Plastics |
Foreign matter
> 2 mm |
Stones
> 5 mm |
Without BDM bags |
1.06a |
1.59a |
0.05 |
With BDM bags |
0.17a |
0
.80a |
0.04 |
a Above guidelines (see reference 2) |
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With BDM bags the amount of conventional plastics in
green waste diminished considerably. BDM bags were also
welcomed by garbage collectors, who said that they made
the collection of organic waste quicker, easier and more
hygienic. However, the bags tested in 1998 needed to be
more user-friendly. The key requirements were better
stability to make them more suitable for households with
weekly collections, instant recognizability and better
transparency for spot-checks during collections.
Professional composting facilities
In communal composting facilities, BDM bags (PCL, Mater-
Bi) decomposed within the usual decomposition period.
The operators failed to detect any impairment of the
decomposition process. An increase in the amount of care
required to sort out foreign matter must be expected at
first, as BDM bags looked similar to other plastics, and the
workers sorting the compost need more time to distinguish
and sort conventional plastics while leaving the BDM.
However, it was found that when compost included BDM
bags, the quality achieved maintained usual target levels.
Laboratory tests
Bags made of PCL (polycaprolacton) and TPS (thermoplastic
starch) fulfilled the decomposition specifications
(mineralization and laboratory composting) according to
DIN draft 54,900.3 Because of their long decomposition
period and the difficulty of making spot-checks for foreign
matter during collection, bags made out of Kraft paper are
not recommended for use in organic waste collection or in
professional composting facilities. The heavy metal analysis
of the films showed that no paints containing copper
(blue, green) should be used; otherwise, the limit for heavy
metals as set forth in DIN draft 54,900 was exceeded.
Environmental impact
The overall environmental impact of the bags was
compared to alternative systems currently in use.
Collecting organic waste in the kitchen has the least
environmental impact when a bucket without a liner is
used and the bucket is rinsed with cold water. However,
the use of BDM bags as liners is demonstrably less
ecologically damaging than if the bucket is washed with
hot water (which uses energy to heat the water), and with
a detergent, as is the case today in more than 70% of Swiss
households. In a study of how 1200 Swiss households
rinsed their organic waste buckets, 30% used cold water,
20% hot water, 25% hot water and detergent and 25% used
washing-up water; this information was used to evaluate
the resources used in Figure 1.The same proportions were
assumed where a BDM liner was used, but with only one
third of the amount of water.
FIGURE 1. A comparison of the environmental impact of collecting organic waste in buckets without a liner, using polyethylene (PE) bags, and with three different types of BDM liners, rinsing, according to three life-cycle assessment models: CML,4 Eco-Indicator '955 and UBP,6 adjusted in relation to the highest environmental impact (y-axis), 1997-98.
Figure 1 shows the environmental impact as
determined by three life-cycle assessment (LCA) models.
Each area of environmental impact (energy, global
warming etc.) is given a number, wit
h 1 being the highest
level of impact. The Eco-indicator '95 and UBP columns
show that overall assessment for the various levels of impact.
The result of the life-cycle assessment shows that the
use of BDM liners in containers has no greater
environmental impact than cleaning with cold water. A
further life-cycle assessment study of Mater-Bi bags
compared with paper bags and PE bags used for the
collection of organic waste in households - realized
according to ISO 14040, including external critical review
- confirmed the results from the table above.7
Test conclusions
The use of BDM bags in organic waste collection is to be
recommended, with the following provisos:
- the BDM bags must be transparent enough for spot-checking
for foreign matter; paper bags are not
suitable for organic waste collection due to opacity
and the eco-profile in the LCA
- no dyes containing heavy metal may be used (in this
respect, the tested products have been further
developed)
- the bags must be strong enough for household use
during a period of at least one week and their
subsequent collection by hand from the kerbside
- BDM bags must have a biodegradable closing
mechanism to prevent the use of non-degradable string
- the BDM bags must pass compostability tests
according to an international standard, i.e. DIN draft
54,900 or today the DIN-EN-13432
- BDM bags must be marked clearly and uniformly so
that retailers, consumers, garbage collectors and
composting supervisors can distinguish them from
ordinary plastic garbage bags.
The bags now fulfil these requirements.
The results of the tests and the conclusions are
published in detail in a comprehensive report in German,8
and in short reports in French and English.9,10
Certification and branding
Based on the results of these tests, and under a SAEFL
mandate, the test supervisors set up a project group
consisting of representatives from manufacturing
companies, retailers, cities, processing plants and
specialized authorities. After three meetings in 1998, the
guidelines for all BDM bags sold in Switzerland were
established as follows:
- the BDM bags have to fulfil the requirements of the
DIN draft 54,900, and they must be registered at DIN
CERTCO; these bags/materials are allowed to bear the
label of DIN CERTCO exclusively (see picture, right)
- the BDM bags must be marked uniformly with a white
grid so that they are distinguishable from bags made
out of conventional plastics; only bags registered at
DIN CERTCO are allowed to bear the white grid
- all the groups involved worked
together to produce a positive
publicity campaign, which
included the following
elements:
- a flyer within the bags'
packaging to inform the
consumer of the use and
disposal, advantages and
limitations of BDM bags
- advertisments outlining the
advantages of BDM bags
- newspaper and magazine
articles giving facts and
figures in ways that are
tailored to their specific
readers
- special meetings with representatives of
communities and managing directors of
composting facilities which included talks about
biodegradable materials and presenting the results
of various tests: this was part of an ongoing
programme to involve all the participants in
discussions surrounding the development of the
product.
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Label of DIN CERTCO that shows compostable materials/products which fulfil the requirements of DIN draft 54900.
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In order to improve the organic waste collection some
communities promoted the BDM bags beside an
assortment of waste containers. These changes were
published in flyers distributed to all households.
Today's state of play
Today the BMD bags are generally accepted in Switzerland
with a few exceptions, and only certified and uniformly
marked bags are sold by wholesalers. The white grid
proved itself in use in organic waste collections and at
composting facilities, and the marked bags can easily be
distinguished from conventional plastic bags. Sales are
increasing and currently exceeding all expectations.
There is high demand for small BDM bags used as liners
for household compost buckets. The number of BDM bags
for large containers (i.e. over 120 litres) is increasing.
'Since May 1999, sales of the bags in
Switzerland have exceeded expectations'
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The fears of some processing facilities about increasing
quantities of foreign matter, insufficient biodegradability
and wind-blown waste did not prove well founded in
practice. This was confirmed in a series of tests by the
Swiss city association.11
A lot of communication and individual consulting
within communities and processing facilities was essential,
due to the small-scale set-up of the many units (there are
250 processing facilities for 3000 communities). The
opposition of a handful of composting facilities at the
beginning of the testing changed to a general acceptance
by the end of this period.
Since 2001 a working group with representatives of
cities' associations, composting associations, wholesalers,
BDM producers and SAEFL meets once a year to exchange
experiences and new developments.
BDM plastic film packaging for carrots and potatoes
produced organically was successfully introduced in by
Migros, the biggest Swiss wholesaler, in 2002. This year,
Migros began to sell compostable disposable plates and
dishes. Once again there was strong opposition from a
handful of composting plants, which were worried about
whether people would be able to distinguish compostable
disposable items from conventional ones. These plants
were also concerned about the raw material for
composting becoming contaminated by conventional
plastics. For this reason, they want the new BDM products
to be marketed as manufactured from renewable
resources, but not as compostable products.
Biodegradable bags in daily use
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Looking ahead
The experiences of BDM bag introduction could be useful
when looking to introduce further biodegradable
products, such as fruit and vegetable packaging, flowerpots
and other garden-related items. Products designed to be
recycled in composting facilities will have to fulfil the
following requirements:
- to guarantee biodegradation according to an
international norm including certification
- to bear a uniform mark to distinguish them from
conventional plastic products
- to be the subject of a proactive publicity campaign
that will reach the
people involved in
every stage in the
product's life-cycle
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A vocal minority
within the composting
industry is not, at the
moment, willing to
accept any new BDM
products at their
plants. This calls for a
new round of explanatory talks and communication, tests
and standardization, which must take place before new
products can be developed and introduced into organic
waste management.
However, biodegradable products made partly from
renewable resources can be successfully processed in
composting facilities. The compost serves as fertilizer for
renewable resources and BDM products serve the interests
of all participants: farmers, manufacturers, retailers,
consumers and processors - they are all a part of their
natural life cycle.
References
- BUWAL .Abfallsortierung 01/02, BUWAL, Bern. 2002.
- FAC. Kompost und Klärschlamm, Weisungen und Empfehlungen der
Eidg. Forschungsanstalt für Agrikulturchemie und Umwelthygiene
(FAC) im Bereich Abfalldünger. Eidg. Drucksachen und
Materialzentrale, Bern. 1995.
- DIN draft 54,900.Testing of the compostability of polymeric
materials. Beuth-Verlag, Berlin. 1997.
- Heijungs, R., Guinee, J. B., Huppes, G., Lankreijer, R. M., Udo de Haes,
H.A. & Wegener Sleeswijk, A. Environmental Life Cycle Assessment of
Products, Guide and Backgrounds, R. Heijungs (ed.), CML Leiden.
1992.
- Goedkoop, M. The Eco-indicator '95,Amersfoort. 1995.
- BUWAL. Methodik für Oekobilanzen auf der Basis der ökologischen
Optimierung. Schriftenreihe Umwelt Nr. 133, BUWAL, Bern. 1990.
- Composto. Life cycle assessments of Mater-Bi bags for the collection
of compostable waste. Novamont SpA, Novara. 1998.
- Kompostforum Schweiz, Stiftung für Konsumentenschutz, EMPA. Test
von Säcken aus biologisch abbaubaren Werkstoffen für die
Grüngutsammlung. Composto, Olten. 1998.
- Kompostforum Schweiz, Stiftung für Konsumentenschutz, EMPA.
Tests des sacs biodégradable pour la collecte des déchets verts.
Composto, Olten. 1998.
- Kompostforum Schweiz, Stiftung für Konsumentenschutz, EMPA.
Tests of biodegradable bags for organic waste collection. Composto,
Olten. 1998.
- Schweizer Städtverband FES/ORED. Fremdstoffuntersuchung im
Grüngut, Schleiss Konrad. 2001.
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