Wastewater treatment plants are highly energy-intensive systems. This research uses Life Cycle Assessment (LCA) to determine the impacts generated during the operation of a wastewater treatment plant. Three different scenarios are analyzed: a baseline scenario that considers a conventional activated sludge treatment technology exploiting data from an existing plant located in central Italy, a second scenario that involves the implementation of MBR technology applied to the baseline scenario, and finally a third scenario that consists of the addition of an anaerobic digester that allows energy recovery from biogas production, followed by a photovoltaic plant capable of supplying the plant energy demand. Global warming potential, eutrophication, and acidification are the environmental categories considered most relevant to emissions. The results showed that the effluent had the highest impact in terms of CO₂ equivalent in all three situations due to the presence of N₂O. Since emissions from biological processes, transportation, and wastewater are almost similar in all three scenarios, it is preferable to focus on the environmental impacts associated with energy consumption. The third scenario involves careful resource management and the use of treatment technologies that allow for a reduction in the use of nonrenewable energy sources in favor of renewable ones.

This study applies the Life Cycle Assessment (LCA) to evaluate the environmental impacts of different types of road construction, including at-grade sections, trenches, embankments, viaducts, and tunnels. The functional unit used is 100 m, and system boundaries consider raw material extraction, transport, construction, and operation based on a 30-year lifetime. Impact categories considered are Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), Photochemical Ozone Creation Potential (POCP), and Human Toxicity Potential (HTP). Results show that tunnels generate the highest impacts during construction, particularly in terms of CO_2eq and SO_2eq, while operational impacts remain similar across all road types. A valuable consideration can be made on the “emissions equivalence” observed when the length of the at-grade road is approximately twice that of the tunnel, enhancing the importance of a “full view” of the impacts. In exploring mitigation strategies, the use of bottom ash from municipal solid waste incineration as an alternative material reduced GWP-related emissions by about 50%. While the existing literature tends to focus on individual types of infrastructure or specific materials, the following work proposes a systemic approach that links design choices to circular economy strategies, quantitatively demonstrating the potential for reducing environmental impacts using secondary materials.