Environmental and health co-benefits for advanced phosphorus recovery

Worldwide food production is largely dependent on rock phosphate, a finite raw material used for the production of concentrated phosphorus fertilizers. With the aim to close the biogeochemical phosphorus cycle across regions and urban–rural systems, advanced phosphorus recovery applies thermochemical and precipitation techniques to transform locally available biogenic materials into concentrated phosphorus fertilizers. Due to insufficient insights into the consequential impacts of these circular processes, opportunities to align advanced phosphorus recovery with agricultural sustainability are still widely unknown. Here we show that environmental and health life cycle impacts are often lower for phosphorus fertilizers sourced from secondary raw materials than for rock phosphate-derived products, especially in areas of high livestock and population density. Including externalities from rock phosphate extraction and avoided current-day management of biogenic materials in the comparative product life cycle severely alters the cost assessment relative to an analysis that considers only internal costs from manufacturers’ production processes. Societal costs incurred for circular products derived from sewage sludge, manure and meat and bone meal are up to 81%, 50% and 10% lower than for rock-derived superphosphate, respectively. Even without accounting for rock phosphate depletion risks, short-term and local environmental and health co-benefits might underlie the societal cost effectiveness of advanced phosphorus recovery. Agriculture depends critically on phosphorus fertilizer from rock phosphate. This study finds environmental and health benefits from instead recovering phosphorus from secondary sources, such as sewage and manure.