Increased global plastic consumption and production boosted the amount of end-of-life (EoL) plastic. Also, 90 % of plastic EoL is either landfilled or incinerated. These unsustainable EoL pathways impact the environment and human health and waste valuable materials. Thus, improvements to the existing recycling infrastructure for sustainable plastic management are needed to enhance plastic circularity. Therefore, this contribution addresses optimizing cost-effective pathways for plastic recycling within the supply chain. The research uses mathematical optimization and the P-graph theoretical framework to calculate recycling costs, encompassing both capital expenditure and operational expenditure for various pathways of plastic recycling. The proposed methodology is applied through a detailed case study in Miskolc, Hungary, revealing estimated recycling costs ranging from 54.9 to 59.28 EUR/ton. This finding provides crucial insights into the economic implications of diverse recycling methods. Also, the study highlights the P-graph model's untapped potential as a resource for decision-makers in plastic recycling, particularly the enumeration of options for further consideration. The work's utility and novelty lie in the model's capability to design cost-effective pathways, offering a tangible contribution to the plastic recycling supply chain. Finally, this contribution offers economic solutions needed to ensure cost-effective sustainable plastic management solutions.

The circular economy has become one of the most popular topics in worldwide sustainability research. The imperious necessity of reducing resource consumption and decreasing waste generation has led to reincorporating materials at the end-of-life (EoL) stage into the productive chain. Nonetheless, the presence of hazardous substances in the EoL stage materials poses a significant challenge for the transition toward the production model. The adequate transformation of these materials into feedstocks requires their correct allocation into recovery plants and final destinations. Such an allocation can be decided by resorting to optimisation by generating the best alternative networks, from where the stakeholders may decide the most suitable recycling scheme. In this work, a graph-theoretic approach is introduced to identify the best alternatives to reincorporate industrial EoL chemicals into the productive chain. This contribution presents the initial approach to this problem, demonstrated through a case study considering the data reported on the publicaccess release inventory data for n-hexane. Different recycling routes are proposed for the case study by optimising the total treatment cost, and their advantages and disadvantages are discussed; moreover, their efficiency concerning the circular economy is measured by comparing the amount of recovered chemicals. By generating plausible recycling alternatives, this work contributes positively to analysing potential alternatives for circular economy and resource conservation in industry.