Circular Supply Chains as Complex Adaptive Systems: a conceptual framework.

Circular Supply Chains (CSCs) are self-regenerative systems adopting the principles of Circular Economy to extract new value from end-of-life resources, extend product life, and increase resource efficiency toward zero-waste operating conditions. CSCs extend the boundaries of closed loop SCs by involving multiple stakeholders, with both firms belonging to the linear supply chain stages and organizations from the external industrial networks, carrying out the circular activities. Both of them are required to collaborate on managing multiple resource flows i.e., by-products and wastes other than raw materials and main products. Resources circulate back to firms belonging to the original supply chain sector, via closed loops, or to different sectors or directly to natural eco-system, via open loops. A higher level of complexity thus characterizes the transition to CSCs. However, despite the interest on the topic, a robust framework exploring the main dimensions regarding the complexity of CSCs is yet to be developed. We address this research gap by developing a conceptual model using the theory of the Complex Adaptive Systems (CASs) as recognized very suitable for studying emergent behaviours of supply chains as well as to investigate the transition of production systems to a circular economy. In the proposed model, CSCs are conceived as set of interconnected agents (e.g., suppliers, assemblers, waste-provider, user, and waste-collector) who self-organize and co-evolve with the external environment. A novel agent-based model is developed to simulate the dynamics of circular supply chains characterized by different levels of internal and external interdependence, and inter-firm relationship mechanisms.