Carbon curves for the assessment of embodied carbon in the wastewater industry

The water and wastewater industry has been tasked with reducing its greenhouse gas (or carbon) emissions. A key component of any emissions reduction strategy is emissions measurement. While operational emissions are reported by the sector on an annual basis, there is a lack of robust data on embodied carbon. The aim of this paper was to develop a practical solution for assessing the embodied carbon in wastewater assets. The analysis revealed a linear relationship between carbon emissions and capital investment in the construction of wastewater treatment works (1.3 tCO₂/£1000) and wastewater pumping stations (0.3 tCO₂/£1000). Carbon emissions from sewer construction were found to increase linearly with increasing pipe diameter, with ductile iron pipelines responsible for higher emissions than polyethylene. Operational carbon is the major component in the whole life carbon of wastewater treatment works, but future decarbonisation of the electricity grid may increase the relative importance of embodied carbon.