Recycling Phosphorus (P) from urban wastewater can secure part of domestic agricultural P supply and contribute to a circular P supply chain. In this paper, we use literature review, stakeholder interviews and analysis, and systems dynamics for the capital cities of Stockholm and Budapest as case studies. We find that political support is a prerequisite for developing the P recycling sector, and policy makers are the most influential stakeholders. P criticality is the main driver for political support. P externalities from mining to sludge disposal should be considered when evaluating P criticality and recycling profitability. We conclude with policy recommendations for the development of the P recycling sector, arguing for legally binding P recycling targets and prioritization of the safest technological solutions available. Our analysis identifies three policy action indicators and five policy interventions in the recycling system.

Phosphorus (P) is an essential macronutrient in agriculture; however, lack of reporting makes its supply chain a black box. By using literature synthesis on the P challenge, we identify four areas where the reporting process is problematic: P reserves and resources; P losses along the supply chain; P externalities; and access to data. We find that in these areas, the reporting system is inconsistent, inaccurate, incomplete, fragmented and non-transparent. We use systems analysis to discuss implications of reporting on the sustainability of the P supply chain. We find that reporting is essential for the achievement of global P governance and the human right to adequate food. It can also inform decision makers and other impacted stakeholders on policies on agriculture, food security, pollution and international conflict. An improved P reporting process also allows a better evaluation of global sustainability commitments such as the United Nations Sustainable Development Goals.

Phosphorus (P) availability is essential for global food security. A system dynamics model running from 1961 to 2050 was built for this study, linking global P supply to social, economic and environmental dynamics at regional level. Simulation results show that phosphate rock (PR) production needs to double by 2050 compared to present levels, in order to match regional P requirements. South Asia, Latin America and the Caribbean, and Sub-Saharan Africa are regions highly dependent on phosphate imports, yet it is here that most of the population growth and future P requirement will occur. Climate impact, eutrophication and phosphogypsum production are some of the main negative environmental dynamics that are becoming increasingly challenging in the coming decades.

The current pandemic has highlighted the vulnerabilities of our food production system. An overwhelming number of studies and reports warn that in a business-as-usual scenario, the global food system will be increasingly challenged to secure food for a growing population. In its current configuration, the food system reinforces social and economic inequalities, and negatively impacts the environment. At the same time, farmers are increasingly dependent on imported agricultural inputs, such as phosphate fertilizers, which makes them vulnerable to major supply disruptions or price spikes. In this study, we used system dynamics modelling to assess several scenarios for decreased regional inorganic phosphate requirement to 2050 in industrializing regions with a growing population. Four scenarios illustrate the policy options of reducing phosphorous demand through i) recycling of phosphorus (P) from municipal wastewater, ii) food loss reduction, iii) a shift to agroecological farming practices; and iv) a combination of the three measures. We found that food loss reduction has the lowest potential in reducing P requirement, while the implementation of agroecological farming practices results in significant decreases in P requirement. East and South East Asia and Sub-Saharan Africa were two regions where scenarios indicated a decrease or a near flattening of P requirement to 2050 compared to 2020. In North Africa and Western Asia, Southern Asia and Latin America and the Caribbean, scenario simulations show increases in P requirement, albeit at much lower rates than in a business-as-usual case.