A methodology to estimate greenhouse gases emissions in Life Cycle Inventories of wastewater treatment plants

The main objective of this paper is to present the Direct Emissions Estimation Model (DEEM), a model for the estimation of CO2 and N2O emissions from a wastewater treatment plant (WWTP). This model is consistent with non-specific but widely used models such as AS/AD and ASM no. 1 and presents the benefits of simplicity and application over a common WWTP simulation platform, BioWin®, making it suitable for Life Cycle Assessment and Carbon Footprint studies. Its application in a Spanish WWTP indicates direct N2O emissions to be 8 times larger than those associated with electricity use and thus relevant for LCA. CO2 emissions can be of similar importance to electricity-associated ones provided that 20% of them are of non-biogenic origin. - Highlights: ► A model has been developed for the estimation of GHG emissions in WWTP. ► Model was consistent with both ASM no. 1 and AS/AD. ► N2O emissions are 8 times more relevant than the one associated with electricity. ► CO2 emissions are as important as electricity if 20% of it is non-biogenic.