Phosphorus Recovery Transition Tool (PRTT): a transdisciplinary framework for implementing a regenerative urban phosphorus cycle

The anthropogenic use of phosphorus has emerged as a one of the major drivers of global environmental change. The finite supply of the nutrient, geographical concentration of the remaining supply, and continuing occurrences of eutrophication and harmful algal blooms (caused, in part, by excessive phosphorus outflows into the environment) are causes for immediate concern. As a response, there is increasing recognition that phosphorus entering waste streams should be recovered as a resource rather than disposed of as a pollutant. While phosphorus recovery technology and strategies have been outlined in some detail in the existing literature, none have explicitly addressed the reasons for why these processes have not been implemented at scale. In addition, the potential for urban systems to play a role in creating a holistic management system for phosphorus has received little recognition. This paper addresses these knowledge gaps by offering a tool for analyzing the context, drivers, barriers, and implementation of phosphorus recovery technologies in urban areas. The framework tool consists of five guiding questions. The process of answering the questions presents an opportunity for researchers, decision makers, and community stakeholders to explicitly identify what and how changes to the current system can be made. This paper provides an approach for producing the knowledge necessary for facilitating the transition to an urban phosphorus recovery regime that is relevant for both practitioners and academics. The approach may also be adapted to understanding other resource cycles in the future, such as nitrogen, water, and energy.