Phosphorus recovery from wastewater: needs, technologies and costs

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.