Life Cycle Assessment of sulfate radical based-AOPs for wastewater disinfection

Water stress is a global issue that is increasingly worsening due to rising water demand and uneven rainfall distribution caused by climate change. Moreover, the quality of water bodies is deteriorating, necessitating the exploration of alternative water sources, such as wastewater reclamation and reuse. However, ensuring the absence of pathogens is crucial in mitigating potential health risks. Advanced oxidation processes (AOPs) that utilize sulfate radicals (SR-AOPs) have been proposed as alternatives to conventional disinfection treatments. The SR-AOPs have the advantage of producing less or no disinfection by-products, but their environmental sustainability must be considered. This study aims to evaluate the life cycle impacts of four SR-AOPs that utilize peroxymonosulfate (PMS) for treatment: PMS/UV-A; PMS/H2O2/UV-A at 1:1 and 1:3 ratios; and PMS/O3. Furthermore, the study assesses the impact of the pilot plant where the treatments are carried out. Results show that PMS/H2O2/UV-A at a 1:3 ratio had the highest environmental impact in nine of the sixteen categories studied (Product Environmental Footprint method), followed by PMS/UV-A. The PMS/O3 treatment scenario had the lowest environmental impact and achieved a 5-log removal of Enterococcus faecalis in the shortest treatment time. Notably, electricity consumption emerged as the most critical factor in assessing the environmental sustainability of the treatments, accounting for between 65 and 90% of the total impact across all scenarios. Additionally, fossil resource depletion and climate change emerged as the most relevant impact categories across all scenarios. In this way, LCA becomes a key tool when making decisions in the selection of treatment scenarios, not only considering the treatment efficiency.