Cascade Biorefinery of Furcellaria lumbricalis Macroalgae: Social Impacts and Integration into a Life Cycle Sustainability Assessment

The sustainable valorization of marine biomass is central to advancing a circular bioeconomy. This study delivers the first integrated Life Cycle Sustainability Assessment (LCSA) of a cascade biorefinery for the red macroalga Furcellaria lumbricalis, evaluating environmental, economic, and, crucially, social impacts. Addressing the limited attention to social dimensions in macroalgae research, a Social Life Cycle Assessment (S-LCA) was performed using the Reference Scale Approach aligned with ISO 14075:2024 and UNEP guidelines. Stakeholder and expert evaluations were applied to two process phases: harvesting and processing. The S-LCA identified notable social benefits, including strengthened local economic development and improved worker social security, alongside moderate risks in occupational health and safety, as well as wealth distribution. These results were integrated with environmental and economic indicators using a multicriteria decision-making method (TOPSIS), comparing the cascade biorefinery (PrAp) with two alternatives: a single-product system (AAp1) and a three-line extraction system (AAp2). The cascade configuration emerged as the most sustainable option, achieving the highest closeness coefficient (0.776) and demonstrating advantages in product recovery, economic performance, and social co-benefits. Sensitivity analyses confirmed the stability of these rankings under varied weighting assumptions. Overall, this research highlights the value of multi-product valorization strategies and provides new insights to guide sustainable blue bioeconomy development, especially regarding underexplored social aspects.