Life Cycle Assessment Of Wastewater Treatment Scenarios

Municipal wastewater treatment plants (WWTPs) are essential for protecting public health and aquatic ecosystems but are also energy-intensive and generate large quantities of sludge and foam wastes that are often incinerated or landfilled, leading to both environmental burdens and the loss of valuable resources. In recent years, WWTPs have been increasingly recognized as potential resource recovery facilities, capable of generating energy and nutrients while reducing pollution. LCA offers a systematic framework to quantify these trade-offs and identify the most sustainable treatment pathways. This study applied LCA to evaluate the environmental performance of three wastewater treatment scenarios on the basis of 1 m³ of influent treated: (i) a baseline conventional activated sludge system with sludge incineration, (ii) a system with anaerobic digestion (AD) of sludge and combined heat and power (CHP) recovery, and (iii) an advanced resource recovery configuration integrating AD, CHP, heat recovery, and struvite precipitation for nutrient recovery. Modeling was performed in SimaPro 9.0.2.0 using the ecoinvent v3.3 database and the ReCiPe Midpoint (H) method, with system expansion to account for avoided electricity, heat, and fertilizer production. Results showed that the advanced recovery scenario achieved the lowest impacts across most categories, reducing global warming potential by 65% compared to the baseline, and significantly mitigating acidification and eutrophication. Contribution analysis confirmed that electricity consumption and sludge disposal dominate environmental burdens in conventional systems, whereas the substitution of avoided products is critical to improving performance in recovery-oriented scenarios. Sensitivity analysis highlighted the importance of allocation methods and the uncertainty of fugitive methane emissions from AD.