Environmental optimization of the Northern Italy supply chain for the treatment of residual plastic packaging waste considering waste-to-energy and chemical recycling technologies

Plastics are key and ubiquitous materials whose increasing consumption poses a challenge with regard to the management of plastic waste. The largest fraction of plastic waste is made of plastic packaging. Only a limited fraction of plastic packaging waste can be mechanically recycled. The residual fraction, called PLASMIX, is either used as an ingredient for secondary solid fuel production, directly incinerated or landfilled. This Thesis aims at proposing a mixed integer linear programming model of the Northern Italian supply chain for PLASMIX treatment, taking into account both the selection of the treatment technologies and the distribution of the material flows among the different actors of the supply chain. The treatment technologies considered in the supply chain model are incineration and two alternative technologies for chemical recycle i.e. gasification and pyrolysis. The model was optimized aiming at minimizing the envornmental impact of the overall supply chain in terms of GHG emissions from the perspective of the final treatment plants. The best environmental result is achieved by a supply chain where only pyrolysis plants are selected, even though this is not the best choice from an economic perspective. However, if pyrolysis oil is sent to cracking units, as an alternative of refined naphtha, revenues are satisfactory and economic and evironmental optimization are aligned.