gregated into two fractions (vegetable food 76% and animal food
24%); glass was disaggregated into two fractions (recyclable glass
96% and non-recyclable glass 4%) and metals into three fractions
(aluminium 10%, steel 70% and other metals 20%). We do not discuss
the uncertainty within these fractions in this article. There
are, however, differences between the data from the cities, the data
from Denmark, and the report from the Norwegian system in terms
of both the numbers of disaggregated fractions and the distribution
between them. This is, however, of little importance for the objective
of this study.
Large variations in the weight-percentages of the main fractions
in the five cities were found. To perform a systematic analysis of
the consequences of uncertainty, the main fractions (paper, plastic,
food, glass and metals) were in turn increased or decreased by 15%.
The remaining fractions were adjusted afterwards, based on their
percentage by weight. The reference waste composition and the
10 alternative waste compositions are found in Table 2.