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Recycling of Plastic Wastes in the Canton of ZugEdelmann W., Schwarzenbach H.U., Arnet M. and Stutz E. Summary of a report in German (55 pages); hard copies may be ordered at H.U. Schwarzenbach, schwarzenbach@zug.ch or zeba@zug.ch Download of the report in German (>6MB!) The
canton of Zug, Switzerland (~100’000 inhabitants), does not possess an own waste
incineration plant. Therefore, already more than ten years ago Zug started to separate as
much garbage as possible in order to increase the recycling rate and to reduce the amount
of waste to be incinerated outside the canton. Separately collected waste, such as green
waste from garden and kitchen, is collected regularly by lorries, while nearly 30 other
fractions can be brought to special collection centres. In each town and village of the
canton there is a so called “Ökihof”, i.e. a main collection centre, where all
separately collected fractions are accepted by specially trained staff. Additionally,
there are decentralised, unobserved containers for glass, metals and Aluminium, which are
within walking distance from home to be
reached easily by foot. This system allows to reduce the amount per capita to be burnt to
about one third compared to communities without separate collection (viz. www.zug.ch/zeba ). Today’s
analyses show that a very large part of the household’s garbage consists of plastic
waste (bottles, containers as well as sheets). This paper reports on the experiences of
Zug with the collection and the use of plastic waste for energy recovery or for recycling
of raw material, respectively. PET and EPS were collected separately quite from the
beginning. In a first phase dating from 1995 till mid 2000, all other plastic materials
were collected without additional separation in order to be burnt in the cement kiln of
Untervaz. Afterwards, for a short time only bottles and containers made out of PE, HDPE
and LDPE (different Polyethylenes) were collected for recycling of the raw material.
Today, in addition to PE’s, also PS (Polystyrol), PP (Polypropylene) and
Polycarbonates are reused for the production of granulates. Because this solution is not
fully convincing, recently there was a search for new solutions, where again the whole
plastic fraction may be treated in a reasonable way. A new process for gasoline production
by treating plastic wastes is proposed to be implied in Zug. The
burning of plastic waste for energetic purposes substitutes for fossil fuels, what
decreases the total amount of greenhouse gas emissions. Detailed reasons are given, why
burning for energetic purposes seems to be the most reasonable use of plastic waste from
households. The main reason is the extremely high number of different kind of plastics
with various qualities each (colours, additives, length of the chains etc.), which hardly can be determined at first
sight even by a professional. In
phase 1, all plastic was collected to be burnt in a cement kiln in Untervaz. The amount of
plastic brought to the centres was increasing every year. At the end of the experiment,
i.e. in the beginning of 2000, about 50% of the total plastic waste of the canton was
collected separately for cement production. Life cycle assessments (LCA’s) showed the
advantage of this solution. Though, the experiment had to be stopped for different
reasons, namely for high Cadmium and Chlorine contents not allowed for secondary fuels by
the current law (originating mainly from
colours in large containers and PVC, respectively). Data on the chemical composition of
the waste and the distribution of the different plastic qualities as well as on different
other technical and social parameters of the experiment are given in this report and in
its annexe, respectively. The
problems of process engineering while burning plastic waste in a cement oven are solved
today. Toxic organic substances are destroyed at high temperatures and inorganic toxic
compounds – such as heavy metals – are fixed inside the cement in non-critical
concentrations or retained by the exhaust gas scrubbing devices. The energy content of
plastic wastes may be used up to seven times better compared
to incineration in a waste incineration plant. Besides these technical benefits, separate
plastic collection showed a very positive effect on general collection behaviour of the
population of the canton: Because plastic
takes a large volume of the “grey” waste bag sent to incineration, there was a high motivation for separate collection; it was
worthwhile to visit the recycling centre more often and to bring other fractions at the
same time. So the total amount of separately collected waste increased considerably. Phase
2 lasted only for the second half of the year 2000: Then, there existed the possibility to
bring – besides of PET and EPS, which always were collected separately for recycling
of raw materials - bottles and containers made out of different kinds of
Polyethylenes to the centres (also for recycling of raw material). A collection bag
of 40 litres could be bought at CHF 1.90, which is considerably less than the price of the
“grey” bag at CHF 2.90 for 35 litres only. Nevertheless, this solution could not
convince, because most of the population was not capable to separate PE’s properly
from other kinds of plastic. The motivation for separate (PE-)plastic collection decreased
very much and there was also a slight negative side effect on the separation of other
fractions. At the same time, the costs to separate out undesired goods at the centres
increased in a not acceptable manner. Phase
3 lasts since 2001: Due to new automated separation technologies, it is now also possible
to bring bottles and containers out of PP, PS and Polycarbonates in addition to those made
out of PE to the Ökihof Zug. This allows to collect most of the plastic goods with solid
walls. Because the separation at the centres is less costly now, the delivery does not
cost any more. This solution improved the situation by increasing the amounts to a certain
extent again. However, there is still a high percentage of the population who does not
take favour of this offer, because there still does not exist a solution for plastic films
(which take a large volume in the grey bag). In
order to offer again a solution comparable to burn the plastics for cement production, new
technologies have been evaluated. Data on the comparison and on the winning process are
given. The comparison led to the conclusion that it seems to be the most reasonable
solution to build a plant for conversion of plastic into fuel with characteristics
similar to diesel fuel. The “Plastic Conversion System, PCS” plant taken into
consideration is capable to convert over 80% of the plastic into fuel by a cracking
process; less than 20% are needed for the process itself or remain as a small part of
undesired by-product, respectively. The plant seems to fulfil the limits imposed by laws
regarding the environmental impacts. Actually, the planning of the plant is in an advanced
state and it seems to be possible to start the construction within 2004. In 2005, it
should be possible to give “green light” to the population for bringing again
all the plastics to the centres. It
has to be stressed, however, that for a long lasting solution it is necessary to impose a
tax on the raw material at the source – e.g.
similar to that on electronic waste - for covering the costs caused by the waste
treatment.
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