The circular economy (CE) is considered a key economic model to meet the challenge of sustainable development. Strenous efforts are focused on the transformation of waste into resources that can be reintroduced into the economic system through proper management. In this way, the linear and waste-producing value chain problems are solved, making them circular, and more sustainable solutions are proposed in those chains already benefiting from circular processes, so that waste generation and waste are reduced on the one hand, and on the other, the non-efficient consumption of resources decreases. In the face of this current tide, there is another option that proposes a certain nuance, based on the premise that, although circular systems promote sustainability, it does not mean that they are in themselves sustainable, given that, in the first place, the effects of CE on sustainable development are not fully known and, on the other hand, the CE model includes the flow of materials, with only scant consideration of the flow of non-material resources (water, soil and energy). This paper aims to contrast both currents from an empirical viewpoint. To achieve this, a sustainability analysis of the circular waste management systems measured through a sustainability indicator, the carbon footprint (CF), as a main sustainable indicator in climate change action, is carried out. A crucial difference between circular models that promote waste management and those that do not is found in the collective systems of extended producer responsibility (or CPR). One of the most efficient recycling processes in Europe, waste tire management, has been chosen. Thus, the aim is to verify the sense of including environmental sustainability indicators, as CF, in the process of these systems. A sustainability management model (SBA) applies to End-of Life tire collection systems (ELT). This model is based on the accumulation of environmental impacts through the activities that generate them. To be transparent, this study requires a publicly recognized CF, so the study is focused on SIGNUS, the main Spanish waste tires CPR. The results achieved allow us to conclude that CF is much lower using CPR than non-linear processes. Despite the role that CPR have in the management and use of waste as secondary raw material, it is a priority to focus efforts on their redesign in order to reduce waste. In terms of circular economy, all actions are necessary in order to achieve system efficiencies, even when externalities occur in this process.
Towards Circular Economy Solutions for The Management of Rice Processing Residues to Bioenergy via Gasification
