Sustainable use of phosphorus Capturing the philosopher’s stone

Phosphorus (P) is essential for all forms of life. It cannot be substituted and it is indestructible as it is a chemical element. Each year, 263 million tons of phosphate rock is mined, but only a fraction makes it back into the soil. Crops are consumed and end up in the sewage system as waste. Even though phosphorus is a scarce element, most phosphorus is lost in water bodies after consumption, leading to extreme algae growth and water pollution. Humanity could only produce half of the food that it does today when phosphorus-containing fertilizers could not be added to the soil. Therefore, phosphates should be recovered and recycled to close the cycle.
In this PhD thesis several essential aspects for converting our current linear P economy to a circular P economy have been discussed. Growing cities entail challenges, but opportunities too. Nowadays, waste is controlled at centralized wastewater treatment plants (WWTPs), which enables urban mining. A particular solution is the recovery of P at these urban mines as struvite or sewage sludge ash, which is progressively more implemented.