Phosphorus recovery from wastewater: needs, technologies and costs

TLDR

Phosphorus is a limited, irreplaceable resource, prompting growing efforts to recycle it from wastewater, though industrial‑scale experience remains scarce. Phosphorus can be recovered from wastewater, sewage sludge, and sludge ash using various methods that often integrate with removal processes. Recovery rates reach 40–50% from liquid and up to 90% from sludge or ash, but the recovered phosphate is several times more expensive than rock phosphate, adding €2–6 per capita per year in German wastewater treatment.

Abstract

Phosphorus is an essential, yet limited resource, which cannot be replaced by any other element. This is why there are increasing efforts to recycle phosphorus contained in wastewater. It involves the recovery of phosphorus and, normally, the separation of phosphates from harmful substances. Phosphorus can be recovered from wastewater, sewage sludge, as well as from the ash of incinerated sewage sludge, and can be combined with phosphorus removal in most cases. The phosphorus recovery rate from the liquid phase can reach 40 to 50% at the most, while recovery rates from sewage sludge and sewage sludge ash can reach up to 90%. There are various methods which can be applied for phosphorus recovery. Up to now, there is limited experience in industrial-scale implementation. The costs for recovered phosphate exceed the costs for phosphate from rock phosphate by several times. For German conditions, the specific additional costs of wastewater treatment by integrating phosphorus recovery can be estimated at €2–6 per capita and year.