Análisis de ciclo de vida en la transición a la economía circular. Caso de estudioel reciclaje en la tecnología de membrana

Abstract

Reverse osmosis (RO) is the foremost extended technology for desalination. RO is a membrane technology. Nonetheless, this technology has some environmental issues such as energy use, brine disposal and the generation of end-of-life (EoL) RO membrane modules. Therefore, research has been carried out on the development of technical solutions. Among others, the efforts in the transition towards circularity of this technology through the innovation in recycling alternatives also need to be highlighted. The novelties in these last years come from novel results at pilot scale recycling into nanofiltration (NF) and ultrafiltration (UF), and the second generation of indirect recycling that includes recycling into forward osmosis (FO), which has been tested at laboratory scale. Nonetheless, there is a knowledge gap in the environmental and economic implications of these technologies. The present thesis aims to update and fulfilled the comprehension of direct recycling into NF, UF and FO. To guarantee environmental protection and prevent the impact of the transition into the Circular Economy and aligned to the Waste Framework Directive (2008/98/EC), the application of Life Cycle Assessment (LCA) has been indicated as the most suitable tool. Therefore, the present thesis applies LCA and other economic assessments to different advancements in the research of EoL-RO recycling. That is the selection of recycling pilots, the integration of the variability of the waste, the supply chain definition and analysis and a holistic assessment with a life-cycle perspective of the recycling into NF and FO. Moreover, a first assessment of the emerging recycling into FO was performed. As for methodological novelties, the development of LCA-based indicators to bridge the data gaps and the uncertainty of technologies at low technology readiness level (TRL) needs to be remarked. The results show that the three recycling technologies, direct recycling into NF and UF; and indirect recycling into FO have a potential low impact on the environment. Furthermore, in most of cases, it has been perceived that they have a lower impact than their commercial counterparts. Nonetheless, the hotspots and other technological barriers could complicate the potential environmental savings from recycling and some research is still necessary for the process definition and waste characterisation. Finally, the present thesis defines the criterion, indicators, and methodologies to continue the research and development enhancing the environmental protection and the economic feasibility of the herein-studied technologies.