Environmental sustainability of phosphorus recycling from wastewater, manure and solid wastes

Phosphorus (P) is an important critical material essential for crops cultivation and animal husbandry. Effective phosphorous recycling is considered one of the most significant factors in alleviating its criticality. However, despite the importance of phosphorous recycling, its sustainability is not studied extensively. This paper aims to answer the question if recycling of phosphorus is an environmentally sustainable option. To address this problem, two issues are analyzed in this paper: energy consumption and greenhouse gas (GHG) emissions in phosphorous recycling. The analysis was performed by simulating mass and energy flows in the global phosphorus supply chain (from mining to recycling) in order to understand and analyze its environmental impact in 2000-2050. The results of simulation show that around 82% of recycled phosphorous originates from manure. Moreover, the calculations indicate that about 70% of total GHG emissions from phosphorous recycling is caused by wastewater processing. In addition, the results show that phosphorous obtained from recycled wastewater constitutes only 2% of the whole amount recovered in the recycling process. Therefore, the obtained results show a clear need for a detailed analysis of the sustainability of phosphorous recycling processes. Moreover, the analysis of scenarios of phosphorus consumption indicates that GHG emissions increase slowly in the mining phase and grow exponentially in the recycling stage. The main finding of this paper contradicts the general opinion about environmental friendliness of recycling. It shows that phosphorus recycling is not a sustainable solution in a longer perspective.