Recycling of phosphorus in urban Sweden: a historical overview to guide a strategy for the future

Sustainable sanitation and food security have been issues in all human history although named differently. This study describes the evolution of sanitation arrangements in the Swedish town Linkoping for the period 1870-2000. The flow of phosphorus from food consumption is estimated for the period and its output is divided into gainful reuse in agriculture and energy production and (harmful) losses to the hydrosphere and landfills. The rate of gainful reuse varies dramatically, from very high, up until the 1920s, followed by a drop to almost zero around 1950. Reuse was picking up since the introduction of a phosphorus removal unit at wastewater treatment plants and application of sludge in agriculture from the 1970s, but was followed by a sharp decline at the end of the 20th century. The results from Linkoping are applied to scenarios for Sweden as a whole and extended to some anticipated implications for the world in the years to come.