Evaluation of Circular Performance Models in Wastewater Treatment Plants: Portugal Case-Study

Population growth, economic growth, and changes in societal habits have led to significant changes in resource consumption. Therefore, it’s crucial to accelerate the reduce, reuse, recycling, and recovery of resources to ensure the balance of ecosystems, and water is surely, one of the most fundamental resources. The acceleration of this approach in the water cycle makes sense only if we combine a circular economy (CE) transition with a sustainable perspective. In this context, more rational usage of water resources (which are under pressure) and more sustainable wastewater practices are expected to be a way towards the CE in the water and wastewater sector. This study provides a description and evaluation of existing frameworks that can be used to measure and assess the level of circularity of WWTP. The treatment of urban wastewater requires new concepts of management and operation for the adaptation of existing plants, which lack robustness and flexibility, to face these new challenges and requirements because we can no longer continue to look at the WWTP only as treatment units, but as wastewater resource recovery facilities. This transformation must be transposed according to a matrix that allows the assessment to describe the current situation, analyse the problem, identify vulnerabilities and opportunities, identify measures, evaluate measures, identify strategies, and evaluate strategies, considering that decision-makers face profound uncertainties such as climate change, population growth, population needs, innovative technologies, economic developments, ecosystems preservation and the impacts of human and natural activities.