The need to transform economic models to implement a circular use of resources is crucial due to the current waste accumulation crisis. New waste-to-resource alternatives are constantly emerging to close material loops; therefore, tools are needed to identify the best synergies to upcycle waste. An approach has been developed to identify and assess waste-to-resource processing routes not currently implemented at the industrial level to valorize waste. The proposed framework consists of several interconnected modules that include ontologies for knowledge management, graph theory and short-path algorithms for the generation of paths and pre-assessment of processes, a Mixed-Integer Linear Programming (MILP) model for superstructure optimization; and the rigorous design, simulation, and optimization exclusively of those alternatives that show the best performance in previous steps. A case study for the treatment of mixed plastic waste reveals chemical recycling and the production of pyrolytic fuels as tentatively favorable options, both environmentally and economically.

The constant development of new alternatives to treat waste aids in closing material loops towards the circular economy and improving sustainability through the use of new renewable materials and energy. This fact leads to the increasing need for decision-making tools for process synthesis and assessment, which can be addressed with an integrated framework that employs ontologies for knowledge management and optimization tools to perform a hierarchical assessment of alternatives. The systematization of these procedures raises the need for tools to automate techno-economic and life cycle analyses. In this work, such a challenge is addressed through the additional integration of add-on modules such as the CapEx-Opex estimation tools and surrogate modeling within this framework. A case study on plastic waste is proposed with the inclusion of several pyrolysis and gasification alternatives. Results show pyrolysis, followed by the subsequent purification of its products, as the best alternative and helped identify main drivers for technologies feasibility such as feedstock purity and energy consumption.