In all scenarios, newspaper (75%), glass (70%) and metal containers (50%) are source separated and recycled outside the studied system. The rest is included in the residual waste within the system boundary. Regarding biodegradable waste, plastic containers (high density polyethylene, HDPE) and cardboard containers, a practically feasible upper limit of 70% source separation in households has been chosen, even though the measured source separation in Sweden only averages some 30%. The high figure is motivated by the method of refining the scenarios to bring out the differences in waste management strategies, aiming at a high degree of source separation in the future if recycling is implemented on a large scale. It is worth mentioning that the goals for materials recycling in Sweden are far below this figure [2]. For companies and industries, 80% source separation of cardboard and plastic is assumed (the source separated plastic also includes low-density polyethylene, LDPE). We believe that companies that are restricted by environmental management systems will show a higher degree of source separation than private households.
The scenarios studied vary slightly between the three municipalities: composting was not seen as an alternative in Stockholm as in the other two municipalities. The potential use of biogas also differed between the municipalities. In this paper, the scenarios for Stockholm are presented in detail, as most results can be derived from this case study alone. The conditions in the studied municipalities differ mainly as follows:
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Stockholm is a densely populated municipality with an incineration plant and a district heating system. Arable land for spreading of the organic fertiliser is available outside the municipality borders.
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Uppsala is a relatively big municipality, also with an incineration plant and district heating system. Arable land can be found close to the city.
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Älvdalen is a small municipality and lacks an incineration plant and district heating system. There is almost no agricultural soil within the municipality borders. As the municipality is sparsely populated, collection of waste is not as efficient as in the other two municipalities.