The impact of climate risk on wastewater treatment plants

Abstract Wastewater treatment plants (WWTPs) are vital infrastructure for public health and the environment, but they are increasingly challenged by climate change. This study aims to assess the interaction between climate risks and WWTP performance. The study integrates expert-based assessment with energy analysis to capture both operational vulnerability and climate-related impacts. A survey of experts highlighted the vulnerability of treatment stages to rising temperatures and increased rainfall. All respondents indicated impacts on sand and oil separation, primary sedimentation, and final sedimentation under elevated temperatures, while 93% emphasized impacts on aeration and disinfection/sludge treatment. Experts also showed near-consensus that increased rainfall affects all treatment stages, with 100% agreement for four stages and 93% for aeration and disinfection/sludge treatment. Regarding the effect of WWTPs on climate change, experts considered the aeration stage to be the most influential, 80%, followed by the inlet stage, 73.3%, and the disinfection/sludge treatment stage, 66.7%. In parallel, the energy analysis of an activated sludge plant (design capacity 40,000 m³/day; actual 28,000 m³/day) showed that aeration is the dominant energy consumer, accounting for more than two-thirds of total electricity use. The Specific Energy Consumption (SEC) was 0.377kWh/m³, and the daily operating cost was about 20,500 EGP, with monthly carbon emissions of approximately 143 tons CO₂-eq. These findings suggest the importance of climate-resilient and energy-efficient wastewater treatment under similar conditions, with relevance to Sustainable Development Goal 6 (SDG 6). Although the results primarily reflect Egyptian WWTPs, they may offer valuable insights for regions with similar climatic and operational conditions.