There is an increasing awareness that resource recycling from urban wastewater is essential to sustainability and circularity. The past decades an increasing number of technologies able to recover various resources from (urban)wastewater have been developed and tested. Many of these processes can be installed at existing wastewater treatment plants but also in novel configurations. These technologies have different specifications and wide operation ranges. Individual technologies, their specifications and operations vary not only technically but also from an economic, environmental and even social perspective. Thus, finding the suitable technological solution for resource recovery from urban wastewater is not yet straightforward. Therefore this research aimed to develop mathematical models to assist well-informed decision-making for resource recovery from urban wastewater. For this, a set of key performance indicators (KPIs) were defined and mathematically formulated (Chapter 2). The KPIs cover technical, economic, environmental and social aspects of unit processes, the context in which these would be placed, and/or of the resources that are recovered. This way the KPIs belonging to these four aspects can serve both model-based evaluation and design of full wastewater treatment and resource recovery plants. Most of these KPIs were applied in a study evaluating the trade-offs of an existing conventional wastewater treatment plant, with and without resource recovery, and a few pre-defined resource recovery plant scenarios (Chapter 3). To enable model-based design of new wastewater treatment and resource recovery trains a conceptual framework of a new decision support tool (NEREUS DST) was developed and demonstrated using some of the KPIs belonging to the four aspects (Chapter 4). The NEREUS DST is able to choose compatible technologies (unit processes) from a knowledge library based on a single, general performance data point per resource per unit process. As an improvement to the method in the conceptual NEREUS DST, process modelling approaches that could be used to generate a wider range of unit process performance profiles were explored (Chapter 5). Three common process modelling approaches, white-, grey- and black-box modelling, mainly differing in complexity, were developed for one of the most commonly applied processes for phosphorous recovery: struvite precipitation. The modelling approaches were compared for applicability and suitability for decision-making in terms of data requirement, computational speed and accuracy. Although the black-box models were the fastest, the grey-box models provided additional understanding. Therefore, grey-box modelling was applied to nanofiltration, a membrane process applicable for both water and nutrient recovery (Chapter 6). Key variables available from practice were used to model nanofiltration, such that DSTs can choose a specific membrane type (material) and the corresponding operational conditions necessary to obtain the targeted resource recovery (water, nitrogen and/or phosphorous). In conclusion, this research has delved into and elaborated on the most important elements of decision-making for the recovery of water, energy and nutrients from urban wastewater. The researched and discussed elements serve as a starting point for further developments to facilitate and eventually accelerate the implementation of resource recovery from urban wastewater.