The sustainability of new and emerging wastewater treatment technologies/systems is a matter of vital significance. In this regard, the life cycle assessment (LCA) of a package type integrated fixed-film activated sludge (IFAS) reactor, treating municipal wastewater, was carried out using SimaPro software (8.0.5 faculty version) and IMPACT 2002 + methodology. The analysis of environmental impacts, associated with the construction phase, and investigated operational scenarios (steady-state, dissolved oxygen variation, and intermittent aeration) of studied IFAS reactor, is presented in this study. The LCA analysis results revealed that the main negative impacts i.e. eutrophication and eco-toxicity of the IFAS reactor were associated with the usage of stainless steel in construction of reactor. It was observed that considering damage indicators, intermittent aeration phase III causes minimum impact (∼43% on human health, ∼2% on ecosystem quality, ∼44% on climate change, and ∼45% on resources), as compared to dissolved oxygen phase III. The study showed that among all the operational scenarios, IA phase III exert ∼2–45% less burden on the environment in most of the midpoint impact categories, except for aquatic eutrophication impact. DO phase III contributed minimum impact on aquatic eutrophication category, mainly due to best effluent characteristics. Overall, the investigations of the present study revealed that among various input resources, energy utilization is the most significant contributor to the environmental impacts associated with the investigated IFAS reactor, and presented the highest importance among four damage categories.