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Phosphorus (P) is an essential element for life, as it plays an essential role in agriculture and many other
applications. However, given its non-renewable aspect, Europe has listed phosphate as one of its main
critical raw materials. In this context, phosphorus recovery alternatives are currently seen as an essential
step for a sustainable cycle of this resource.
The EU does have plenty of phosphate in agricultural and sewage wastewater and, in many wastewater
treatment plants, the produced sludge is dewatered and the concentrated fraction is incinerated. Different
authors reported that after incineration, there is still a considerable phosphorus fraction in the final residues
(ashes), placing this material as a possible source for recovery.
The Dutch start-up company SusPhos has developed a process to recover P from Incinerated Sewage
Sludge Ash (ISSA) and, for this purpose, the partnership between the company and the Water Technology
Lectoraat of NHL Stenden aimed to structure and optimize the process for industrial scale. In this project, a
continuous reactor for ISSA acid leaching was designed, in order to switch the process from a batch to
continuous operation. Besides that, several analysis on the physical-chemical properties of ISSA were
applied in order to characterize it as a starting material and improve the process.
Phosphorus is an essential element for life, whether in the agricultural sector or in the chemical industry to make products such as flame retardants and batteries. Almost all the phosphorus we use are mined from phosphate rocks. Since Europe scarcely has any mine, we therefore depend on imported phosphate, which poses a risk of supply. To that effect, Europe has listed phosphate as one of its main critical raw materials. This creates a need for the search for alternative sources of phosphate such as wastewater, since most of the phosphate we use end up in our wastewater. Additionally, the direct discharge of wastewater with high concentration of phosphorus (typically > 50 ppb phosphorus) creates a range of environmental problems such as eutrophication . In this context, the Dutch start-up company, SusPhos, created a process to produce biobased flame retardants using phosphorus recovered from municipal wastewater.
Flame retardants are often used in textiles, furniture, electronics, construction materials, to mention a few. They are important for safety reasons since they can help prevent or spread fires. Currently, almost all the phosphate flame retardants in the market are obtained from phosphate rocks, but SusPhos is changing this paradigm by being the first company to produce phosphate flame retardants from waste. The process developed by SusPhos to upcycle phosphate-rich streams to high-quality flame retardant can be considered to be in the TRL 5. The company seeks to move further to a TRL 7 via building and operating a demo-scale plant in 2021/2022.
BioFlame proposes a collaboration between a SME (SusPhos), a ZZP (Willem Schipper Consultancy) and HBO institute group (Water Technology, NHL Stenden) to expand the available expertise and generate the necessary infrastructure to tackle this transition challenge.