The need for a more circular use of nutrients, notably phosphorus (P), has been widely discussed in Sweden, not least in response to the release of the new enquiry on sustainable use of sewage sludge (SOU 2020:3). But what would a transition to a circular economy for phosphorus look like? How much phosphorus is needed for biomass production in Sweden? And what possibilities are there to replace the widely used virgin mineral phosphorus with phosphorus from secondary sources?
In a paper published in Sustainability, Lorick et al. (2021) estimated the theoretical recirculation potential for phosphorus in Sweden. To this effect, the study quantified phosphorus flows entering and exiting biomass production sectors, as well as losses of phosphorus to waterbodies, landfills, and equivalent. In order to evaluate the potential suitability of phosphorus-rich waste flows for re-circulation, currently underutilized flows were characterized in terms of phosphorus concentration, plant availability, contamination, and geo-spatial distribution.
The results indicated a considerable potential for increasing the circularity of P flows in both agriculture and forestry in Sweden. Fully utilizing the phosphorus that currently is lost to landfills or equivalent could increase the share of nutrient inputs that can be supplied with recirculated phosphorus from 62 to 77 percent for agriculture, and from 10 to 80 percent for forestry. In addition, there is a large amount of phosphorus in mining waste that could potentially be used for fertilizer production.