Circular Economy Applications to Urban Water Systems: Strategies to Enhance Sustainability

Urban Water Systems (UWS) face significant material availability, waste management, and resource challenges. Applying the Circular Economy (CE) paradigm can enhance the sustainability of UWS by increasing water, energy, metals, and nutrient availability through resource recovery and system decentralization. The CE concept has been adopted in different UWS and management strategies; however, more research was needed on the application in Urban Water Management from a broad perspective, considering multiple studies and different CE strategies. Hence, this study uses a semi-structured methodology to identify the overall challenges and opportunities of CE applications in UWS and propose application strategies. The study identified many opportunities and challenges, such as the lack of integration among the different UWS that prevents CE from reaching its full potential and the possibility of recovering energy, nutrients, water, and metals in a unified system, reusing these resources on-site (e.g., reuse of metals to recover phosphorus). Another critical challenge is the rebound effect, which is rarely studied in UWS and has yet to be measured in UWS. Future studies should establish sustainability indicators and evaluate the sustainability performance of material use in UWS, aiming to develop sustainable solutions for each UWS.