Social life cycle assessment of microalgae-based systems for wastewater treatment and resource recovery

Abstract

The aim of this study was to assess the social impacts of microalgae-based systems for wastewater treatment and bioproducts recovery by using the Social Life Cycle Assessment (S-LCA) tool. In particular, two systems were analysed: 1) a system treating urban wastewater, and 2) another system treating wastewater from the food industry. Moreover, these alternatives were compared to 3) a system for bioproducts production from microalgae grown in a standard growth medium. The recovered bioproducts in all the systems considered were: natural pigments, biogas and digestate, which can be reused as biofertilizer. Results showed that the scenario using standard growth medium was the one showing the best results in all impacts and stakeholder categories (up to 24-fold lower impacts depending on the impact category). This was mainly due to: i) the simplicity of the system, which consequently improves health and safety for workers; ii) the absence of contaminants which consequently improves health and safety, acceptability and olfactory impact for both consumers and the local community; iii) the presence of well-established legislation, regulatory frameworks, and full-scale deployment, which benefit value chain actors and society. Overall, this study also identified several social factors hindering a transition towards a circular bioeconomy in the microalgae-based systems for the wastewater treatment and resource recovery sector.