The environmental impacts of rainwater treatment technologies remain unaddressed, despite increasing efforts to manage stormwater and combined sewer overflows (CSOs). This study applies a Life Cycle Assessment (LCA) to evaluate the environmental implications of innovative solutions developed within the StopUP project (Grant Agreement No. 101060428), aiming to identify processes contributing significantly to climate change and support the design of more sustainable practices. The assessment follows ISO 14040/44 and applies ReCiPe 2016 using ecoinvent v3.10 as background database and a funcTonal unit of 1 m³ of treated water. Two groups of technology systems are analysed: (1) CSO treatment systems, including the retention soil filter (RSF) in its as-built form and compact variants with chitosan, the smart WWTP management approach, and the improved constructed wetland (ICW); and (2) runoff management systems, comprising the sand–gravel filter (SF)and the bioretention cell (BRC). Results show that smart WWTP management achieves the lowest global warming potential (GWP) (0.097 kg CO₂ eq m⁻³), while ICW has the highest (0.51 kg CO₂ eq m⁻³). Among runoff systems, BRC performs best (0.12 kg CO₂ eq m⁻³). Sensitivity analyses reveal that using renewable electricity reduces energy-related emissions by up to 90%, industrial-scale chitosan production lowers RSF impacts by nearly 50%, and improved influent quality decreases ICW emissions by 66%. Transportation also plays a critical role, with shorter distances reducing impacts by up to 27%. Further assessment of additional impact categories, such as eutrophication and ecotoxicity, is recommended to complement the environmental profile of the technologies.
Silva et al. (Thu,) studied this question.