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Municipal collection of packaging glass from households
The collection of packaging glass in Denmark should be improved with the purpose of
increasing the amount collected as well as the quality of the collected glass. This is
stated in the Danish national waste plan, Waste 21.
The quality of the collected glass can be expressed as the part of cullet in the glass.
Cullet means all broken glass, but also includes packaging glass, broken or unbroken, that
cannot be reused. The lower the content of cullet is, the better is the glass quality.
From an environmental point of view, it is advantageous to reuse wine bottles in favour
of recycling the glass by re-melting. It is also environmentally profitable to collect as
much of the packaging glass as possible.
The aim of the project was to identify the components of the municipal glass collection
and handling systems that are critical to obtaining the largest amounts possible of glass
of the best quality.
The municipal glass collection systems compete with collection by retail shops, scouts
and others. The ability of the municipal system to collect glass in both large quantities
and of good quality should be assessed in this context. This means e.g. that a limited
amount of glass of low quality collected by the municipal system does not necessarily mean
that the municipal collection system is inefficient. The reason may be that retail shops
and others collect a significant portion of the waste glass potential, and retail shops
often only collect reusable packaging glass while the rest is delivered to the municipal
glass collection.
The collection systems in fifteen selected municipalities were reviewed. In order to
compensate for the influence of other collection systems in the individual municipalities,
an examination was carried out, to the extent possible, to identify and evaluate the other
glass collection systems in the municipality.
No single municipal system that meets all demands as to collection efficiency and
quality was identified, but the review revealed components of several systems that
contributed to increased amounts and to the quality of the glass collected.
On the basis of reviews of fifteen selected municipal collection and handling systems,
it was outlined how the "ideal municipal system" both regarding efficiency and
glass quality could be pieced together.
The municipalities were selected in a way that allowed for the representation of
significantly different collection systems, differences in municipality sizes, broad
representation of municipalities from both rural and urban areas together with other
characteristics of the collection systems and municipalities.
Five of the fifteen municipalities had established kerbside collection while ten had
bring collection systems often combined with additional collection possibilities at the
household. Two of the municipalities had containers for separation of the glass into
coloured and white glass. One municipality had containers for both collection of intact
bottles for reuse and for packaging glass - broken or unsuitable for reuse.
Not unexpectedly, the review revealed that the amount of glass collected by the
municipality systems was influenced by the easiness to deliver the glass to the collection
system. Also sufficient and accessible information about the systems seems to be essential
for successful collection.
The glass of the best quality was collected in municipalities where the citizens
deliver the glass wrapped up in plastic bags distributed by the municipality or in casual
cardboard boxes. The glass is placed outside the house and collected by the municipal
contractor. The contractor either places the glass directly on pallet collars or, in one
case, in a special collection truck. It is assessed that this further handling by the
contractor is important to the glass quality.
The collection systems collecting considerable amounts of glass of good quality were
subject to an environmental screening in which especially the energy balance was assessed.
In general, the screening indicated that efforts made in the municipalities to collect
considerable amounts of glass of good quality were at least counterbalanced by the energy
savings caused by the collection of glass of good quality. The use of plastic bags made
considerable inroads into the energy savings caused by the successful collection, but
still, the energy balance in general was positive.
The working environment of the three most successful collection systems was screened,
and it was obvious that fundamental improvements were urgent in two of them.
In one municipality, the glass was transported from the collection site to the sorting
plant in the collection container used by the public. The glass was brought directly to
the sorting table where it was gradually tipped out on the table. This way of operation
resulted in glass of good quality.
In another municipality, the glass was collected in pallet collars and containers
respectively. The system implied that the citizens sorted the glass in reusable bottles
and in cullet when they delivered it. The sorting was of good quality.
Three ideal municipal glass collection systems were outlined indicating the most
important components that, on basis of the findings of the project, seemed to be critical
to a successful glass collection.
The systems encompassed a kerbside system, a bring system and a system where the
citizens themselves place the bottles on pallet collars.
The most significant component of the identified collection systems were:
Kerbside system