Nutrient recovery is an integral part of sustainable clean energy production where one of the most important nutrients is phosphorus (P). Phosphorus recovery from biomass and waste ashes has been a hot topic for research and development activities for decades. However, the chemical speciation of heavy metals (HM) that may be included in recovered phosphates is yet to be resolved. Numerous trial and error approachs have been applied to lower the amount of HM content by fuel design and/or additives. Nevertheless, the connection between P and HM is theses complex phosphate systems on the atomic level is not fully understood. Therefore, exploring if HM are associated with phosphates is paramount for creating a naturallink between sustainable energy production and primary production of biomass.
This study aims to examine the formation of different phosphates found in ashes and the potential inclusion of HM in their structures. The inclusion of Zn and Cu in whitlockite phosphates is investigated by powder X-ray diffraction and FTIR/RAMAN spectroscopy to identify possibilities and challenges with direct application of P-rich ash fractions as a nutrient source for plants. These measurements will be complemented by synchrotron-based X-rayabsorption spectroscopy analysis in future work.