The efficient and timely removal of organic matter and nutrients from water used in normal municipal functions is considered to be the main task of wastewater treatment plants (WWTPs). Therefore, these facilities are considered to be essential units that are required to avoid pollution of the water environment and decrease the possibility of triggering eutrophication. Even though these benefits are undeniable, they remain at odds with the high energy demand of wastewater treatment and sludge processes. As a consequence, WWTPs have various environmental impacts, which can be estimated and categorized using Life Cycle Assessment (LCA) analysis. In this study, a municipal WWTP based in Poznań, Poland, was examined using the method defined in ISO 14040. ReCiPe Endpoint and Midpoint (v1.11), in a hierarchical approach, were used to evaluate the environmental impacts regarding 18 different categories. All calculations were conducted using a detailed database from 2019, which describes each chosen facility. It was found that the energy component, related to the wastewater treatment process demand and electricity production, is the main determinant of the sum of the environmental impact indicators in light of the modelled energy mix. Therefore, it determines the entire process as an environmentally friendly activity.

Wastewater treatment plants (WWTPs) are significant sources of greenhouse gas (GHG) emissions, particularly methane (CH4) and nitrous oxide (N2O). This study compares two widely used carbon footprint (CF) calculation tools, CFCT and ECAM, and validates their results with a self-developed Validation Tool. The findings reveal substantial differences in CF estimates, with ECAM reporting emissions more than twice as high as those computed by CFCT. The Validation Tool, which incorporates site-specific empirical emission factors (EFs), estimates emissions approximately 80% lower than the other tools. The analysis identifies key methodological limitations, including the oversimplification of N2O emissions in CF models, inconsistencies in EF selection, and the lack of standardized validation methodologies. The study underscores the need for refining CF methodologies by integrating real-world operational data and establishing harmonized validation frameworks to enhance the reliability of emissions accounting.