Environmental evaluation of plastic waste management scenarios
The management of the plastic fraction is one of the most debated issues in the discussion on integrated
municipal solid waste systems. Both material and energy recovery can be performed on such a
waste stream, and different separate collection schemes can be implemented. The aim of the paper is to
contribute to the debate, based on the analysis of different plastic waste recovery routes. Five scenarios
were defined and modelled with a life cycle assessment approach using the EASEWASTE model. In
the baseline scenario (P0) the plastic is treated as residual waste and routed partly to incineration with
energy recovery and partly to mechanical biological treatment. A range of potential improvements in
plastic management is introduced in the other four scenarios (P1–P4). P1 includes a source separation of
clean plastic fractions for material recycling, whereas P2 a source separation of mixed plastic fraction for
mechanical upgrading and separation into specific polymer types, with the residual plastic fraction being
down-cycled and used for “wood items”. In P3 a mixed plastic fraction is source separated together with
metals in a “dry bin”. In P4 plastic is mechanically separated from residual waste prior to incineration.
A sensitivity analysis on the marginal energy was carried out. Scenarios were modelled as a first step
assuming that marginal electricity and heat were based on coal and on a mix of fuels and then, in the
sensitivity analysis, the marginal energy was based on natural gas.
The study confirmed the difficulty to clearly identify an optimal strategy for plastic waste management.
In fact none of the examined scenarios emerged univocally as the best option for all impact categories.
When moving from the P0 treatment strategy to the other scenarios, substantial improvements can be
obtained for “Global Warming”. For the other impact categories, results are affected by the assumption
aboutthe substituted marginal energy. Nevertheless, irrespective ofthe assumptions on marginal energy,
scenario P4, which implies the highest quantities of specific polymer types sent to recycling, resulted the
best option in most impact categories.
Environmental evaluation of plastic waste management scenarios
The management of the plastic fraction is one of the most debated issues in the discussion on integrated
municipal solid waste systems. Both material and energy recovery can be performed on such a
waste stream, and different separate collection schemes can be implemented. The aim of the paper is to
contribute to the debate, based on the analysis of different plastic waste recovery routes. Five scenarios
were defined and modelled with a life cycle assessment approach using the EASEWASTE model. In
the baseline scenario (P0) the plastic is treated as residual waste and routed partly to incineration with
energy recovery and partly to mechanical biological treatment. A range of potential improvements in
plastic management is introduced in the other four scenarios (P1–P4). P1 includes a source separation of
clean plastic fractions for material recycling, whereas P2 a source separation of mixed plastic fraction for
mechanical upgrading and separation into specific polymer types, with the residual plastic fraction being
down-cycled and used for “wood items”. In P3 a mixed plastic fraction is source separated together with
metals in a “dry bin”. In P4 plastic is mechanically separated from residual waste prior to incineration.
A sensitivity analysis on the marginal energy was carried out. Scenarios were modelled as a first step
assuming that marginal electricity and heat were based on coal and on a mix of fuels and then, in the
sensitivity analysis, the marginal energy was based on natural gas.
The study confirmed the difficulty to clearly identify an optimal strategy for plastic waste management.
In fact none of the examined scenarios emerged univocally as the best option for all impact categories.
When moving from the P0 treatment strategy to the other scenarios, substantial improvements can be
obtained for “Global Warming”. For the other impact categories, results are affected by the assumption
aboutthe substituted marginal energy. Nevertheless, irrespective ofthe assumptions on marginal energy,
scenario P4, which implies the highest quantities of specific polymer types sent to recycling, resulted the
best option in most impact categories.
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