Author(s): Sailaja Poudel; Peter Leonard; Sean Mulligan; Eoghan Clifford

Linked Author(s):

Keywords: Hydraulic Structures; Wastewater Treatment; Life Cycle Assessment; Climate Change; Sustainable Infrastructure

Abstract: Wastewater treatment plant (WWTP) infrastructure is required to treat wastewater from different sources, such as homes, industries, offices and hospitals, before safely discharging it to the environment. Although WWTPs play an important role in safeguarding the environment, they also have some level of environmental impact during their construction, operation and decommissioning at end-of-life. It is crucial to holistically quantify these impacts to progress design and operation frameworks towards more sustainable WWTPs. However, there are still gaps in understanding the magnitude of embodied environmental impacts in WWTP infrastructure. Therefore, this study evaluates the embodied carbon and other impacts of a notional small to medium scale WWTP in Ireland (population equivalent of 4,500 people). This study focuses on the corresponding emissions related to key infrastructure, namely the primary clarifier, aeration tank, secondary clarifier, control building and mechanical equipment (for example aeration equipment), that arises from different life cycle stages of the WWTP plant. The life cycle stages considered in this study are raw material stage, transportation stage, construction stage, operation stage and end-of-life stage. However, this study is to serve as a guide on conducting Life Cycle Assessments (LCA) of WWTPs for future research and does not represent a complete LCA of a WWTP. The analysis was carried out using SimaPro v 9.6. 0.1 in accordance with EN15804 (+ A2 revision). The assessment of impacts was carried out across different impact categories using the normalization and characterization methods provided in SimaPro. Based on normalization impact assessment, resource usefossils were found to be a significant impact category with highest points for the aeration tank. This study shows that in the context of embodied impacts, the aeration tank is the largest contributor at a WWTP as it is both material intensive and energy intensive, with significant energy consumption during the operational phase. The operational phase of the aeration tank for a 50-year life span also significantly impacts the Global warming Potential (GWP) (1,770,000 kg CO2 eq), emphasizing the need for energy-efficient mechanical equipment. Cement production was the one of the primary drivers of Global Warming Potential (GWP), with the construction of the aeration tank alone contributing approximately 141,000 kg CO2 eq. Although end-oflife recycling of reinforcement (rebar) offsets impacts, it only represents 3.44% of overall carbon emission of the facility within the scope of this study.

DOI: https://doi.org/10.64697/978-90-835589-7-4_41WC-P2060-cd

Year: 2025