The German Federal Ministry of Education and Research (BMBF) has launched the Regional Phosphorus Recycling (RePhoR) funding measure as part of the BMBF's “Research for Sustainable Development” strategy with view to the classification of phosphorus as a critical raw material. In the research project “Regional sewage sludge and ash management for phosphorus recycling in a metropolitan area” (AMPHORE), five waterboards located in North Rhine-Westphalia currently develop a concept for phosphorus recycling for one of the largest metropolitan areas in Germany. As part of the project, phosphorus recovery including heavy metal removal is investigated in a large-scale demonstration plant using the wet-chemical, ash-based PARFORCE Technology®. The phosphoric acid produced in application-specific qualities enables a demonstration of regional applicability in various branches of industry. In order to guarantee both the highest possible quality of recycling and the greatest possible safety of disposal, the qualities and possible recycling paths of the by-products and residual materials are also being considered. This article will focus on the products and residues of phosphorus recovery and their potential uses.