A ‘Clean’ process to recover phosphorus from sewage sludge ash

Developing sustainable sources for critical raw materials is essential in the transition to a circular economy. And while there are possible replacements for finite resources, how those materials are extracted needs consideration.    

08 Jun 2022

Incinerated sewage sludge has incredible potential as a key resource in a circular economy. It can yield valuable materials like copper and iron, as well as nitrogen. But most significantly, it also contains phosphorus.

An essential ingredient in fertilisers and an additive for livestock feed, phosphorus mainly comes from phosphate rock. It’s a non-renewable resource with a massive carbon footprint from mining and transport.

A way to recover phosphorus from sewage sludge ash that’s scalable to industrial levels, like EasyMining’s patented Ash2Phos process,  could be extraordinarily beneficial. Sewage sludge doesn’t run out and can be found wherever there are large population centres.

Yet, simply replacing phosphate rock with phosphorus recovery won’t solve things. The process has to be clean — environmentally responsible and conserving of resources — to truly be part of a sustainable society.

That’s why EasyMining co-launched the Clean Phosphorus Initiative 2029. Founded by companies dealing with either wastewater management or phosphorus recovery, the initiative advocates for clean phosphorus recovery in Germany, where wastewater treatment plants are required to begin recovering phosphorus from sewage sludge ash in 2029.

As a first step, the initiative crafted several agreed-upon qualities for a process to be “clean phosphorus recovery”.

Key qualities of clean phosphorus recovery

  • The process does not cause any additional accumulation of pollutants on fields, arable land, or cultivated areas.

  • The process separates phosphorus recovery into product and residual material fractions in a manner that assures quality regardless of the composition and pollutant load of the starting material.

  • The process fosters independence from the import of phosphorus through reliance on domestic sources.

  • The process produces clean and universally applicable, marketable phosphorus products that are needed and further processed in the established structures of the phosphorus processing industry.

  • The process removes the pollutant substances from the material cycle.

  • The process enables the separate recovery of as many valuable materials as possible from the ashes.


Please download a PDF of the “Clean Phosphorus 2029” position paper to read more about the Clean Phosphorus Initiative 2029 and the key qualities of clean phosphorus recovery from sewage sludge ash.