Comparative life cycle assessment of energy and coagulant optimisation in real and virtual water treatment plants

Conventional water treatment plants depend on aging pumps, energy-intensive equipment, non-renewable energy sources, and chemical coagulants, significantly contributing to environmental degradation and climate change. This study conducted a comparative life cycle assessment (LCA) of four conventional water treatment plant scenarios: one real plant and three virtual plant models. The first virtual plant incorporated energy consumption optimisation, the second substituted only the coagulant, and the third integrated both energy optimisation and coagulant substitution. The real plant, with a treatment capacity of 3.15 m³/s, served as the baseline. Using the openLCA 2.3.0 and the Centrum voor Milieuwetenschappen Leiden (CML) v4.8 method, environmental impacts were assessed for treating a cubic metre of water. The results showed that virtual plant 3 significantly reduced environmental impacts by up to 85.49% compared to the real plant in the impact category of metal/mineral resources. The average carbon footprint for treating 1 m³ of water decreased from 0.492 kg of CO₂ equivalent (CO₂-eq) for the real plant to 0.237 kg of CO₂-eq for virtual plant 3, representing a 51.83% reduction. Sensitivity analysis confirmed the robustness of the assumptions. These findings highlight the potential for sustainable practices in water treatment, aligning with the United Nations Sustainable Development Goals (SDGs) 6 (Clean Water and Sanitation), 12 (Responsible Consumption and Production), and 13 (Climate Action).