Comprehensive evaluation of the carbon footprint components of wastewater treatment plants located in the Baltic Sea region

Finland and Poland share similar environmental interests with regard to their wastewater effluents eventually being discharged the Baltic Sea. However, differences in influent characteristics, treatment processes, operational conditions, carbon intensities of energy mixes both countries make these two interesting for footprint (CF) comparison. This study aimed at proposing a functional unit (FU) which enables comprehensive comparison plants (WWTPs) terms CF. Direct emissions had highest contribution (70%) total Energy consumption dominated indirect by over 30%. Polish WWTPs benefitted more from self-sufficiency than Finnish as result higher electricity emission factors Poland. The main difference between were attributed chemical WWTPs. Total pollution equivalent removed (TPErem) FU proposed enabled better located different High correlations TPErem other FUs found since could balance out removal efficiencies various pollutants. Offsetting CF was proper strategy studied move towards low-carbon operation. reduce up 27% practices, such selling biofuel, fertilizers. These findings are applicable widely selected represent typical solutions Poland, Sea region.