New urban settlements are sprouting up at a rapid pace around the world. Implementing the required water, waste, and energy infrastructure brings about a number of socio-technical challenges, including water scarcity, resource intensity, and environmental pollution. However, it also provides an opportunity to transition from the current linear model to a sustainable circular model in the built environment. Alternative future circular systems, in which the management of water, wastewater, waste, and energy is integrated, offer potential for increasing resource efficiency and reducing environmental impacts and costs. Such systems are based on the principle of wastewater separation at source. In this process, wastewater is separated into two or more streams at the household level. The technical design of the systems can vary depending on the local context. An alternative system concept includes using blackwater containing fecal matter mixed with household organic waste to enable more efficient biogas production and local fertilizer production. Slightly contaminated greywater, on the other hand, is treated separately according to the “fit for purpose” principle and is intended to contribute to local water supply from alternative sources.

However, the transformation toward a sustainable circular water-waste-energy system goes beyond technical aspects and also depends on social, institutional, cultural, political, economic, and ecological factors. Selecting and implementing a transformation path therefore requires trade-off decisions, which can be challenging for decision makers due to the complexity of the problem and the differing preferences of stakeholders. The present work therefore focuses on the following research question: “How can key factors influencing the transformation toward a sustainable circular water-waste-energy system be integrated and systemized to support a decision-making process that considers the preferences of the various stakeholders?”

The following outcomes are expected:

1. Insights into technical and non-technical barriers and enablers for the successful implementation of sustainable circular water-waste-energy systems in Chile.
2. Development of a supportive model that illustrates the interplay among stakeholders with their respective roles, needs, and values as well as their influence on decisions regarding the transformation of the water-energy-waste nexus (in Chile/Latin America).
3. Development and sustainability assessment of future circular water-waste-energy scenarios, considering a system perspective and the needs and preferences of stakeholders. To this end, a mixed-methods approach is used, including stakeholder analysis, cross-impact analysis, and multi-criteria decision analysis to ensure a holistic system perspective.