Phosphorus (P) is a vital and irreplaceable nutrient for plants. As the world population continues to increase, so does the demand for phosphorus-based fertil-izers to support intensive agricultural activity. However, the European Union faces the risk of supply of these fertilizers and the European Commission listed phosphate rocks in 2014 and then P in 2017 in the list of “critical raw materials”. Cattle manure has long been used as a fertilizer, but to reduce this dependence, it is important to find secondary alternative P supplies, which include sewage sludge and agricultural wastes such as aviary manure, but these cannot be directly used in soils. The inciner-ation of these waste streams not only avoids environmental and health problems but also produces energy while generating P-rich ashes. To further explore this option, this chapter will compare the characterization and potential secondary applications of P-rich ash byproducts generated from fluidized bed incineration of laying hens’ manure at Güres Energy (Turkey) and from stoker incineration of poultry litter rice husks at Campoaves (Portugal). The use of combustion systems and various fuels to produce ash has long been studied, but the effects of these systems on the specia-tion of P in ash are not as well understood. In this study, global samples of bottom ash (BA), economizer fly ash (FAECO), and cyclone fly ash (FACYC) are char-acterized in detail chemically (proximate and elemental analysis), morphologically (microscopy and X-ray microanalysis), and mineralogically (X-ray diffraction). In addition, a novel approach to assessing the environmental impact of new technologies was developed based on the use of two parameters—embodied energy and carbon footprint—and a dimensionless index—the ESCAPE index—that allows compar-ison of the environmental impact of selected substitutes and processes. Elemental analysis reveals that P concentrations in the ash samples are in the medium to low range of phosphate ores, and SEM analysis reveals the presence of phosphospheres and P-rich morphotypes in the fly ash. Analysis of Güres and Campoaves ash samples has revealed that P is mainly present as hydroxyapatite crystals, CaCO3 relics, and CaO, as well as Na–K-Mg phosphate, unburnt char, and silica phases. The high P content of these ashes makes them promising for recovery purposes. The ESCAPE approach was validated and found to accurately evaluate the environmental impact of P recovery techniques, with wet sulfuric acid-based processes being the most appropriate and thermal-reduction dry processes being less sustainable.
Maximizing Phosphorus Recovery from Waste Streams Through Incineration
Fahimi A.;Bontempi E.
2024-01-01
Abstract
Phosphorus (P) is a vital and irreplaceable nutrient for plants. As the world population continues to increase, so does the demand for phosphorus-based fertil-izers to support intensive agricultural activity. However, the European Union faces the risk of supply of these fertilizers and the European Commission listed phosphate rocks in 2014 and then P in 2017 in the list of “critical raw materials”. Cattle manure has long been used as a fertilizer, but to reduce this dependence, it is important to find secondary alternative P supplies, which include sewage sludge and agricultural wastes such as aviary manure, but these cannot be directly used in soils. The inciner-ation of these waste streams not only avoids environmental and health problems but also produces energy while generating P-rich ashes. To further explore this option, this chapter will compare the characterization and potential secondary applications of P-rich ash byproducts generated from fluidized bed incineration of laying hens’ manure at Güres Energy (Turkey) and from stoker incineration of poultry litter rice husks at Campoaves (Portugal). The use of combustion systems and various fuels to produce ash has long been studied, but the effects of these systems on the specia-tion of P in ash are not as well understood. In this study, global samples of bottom ash (BA), economizer fly ash (FAECO), and cyclone fly ash (FACYC) are char-acterized in detail chemically (proximate and elemental analysis), morphologically (microscopy and X-ray microanalysis), and mineralogically (X-ray diffraction). In addition, a novel approach to assessing the environmental impact of new technologies was developed based on the use of two parameters—embodied energy and carbon footprint—and a dimensionless index—the ESCAPE index—that allows compar-ison of the environmental impact of selected substitutes and processes. Elemental analysis reveals that P concentrations in the ash samples are in the medium to low range of phosphate ores, and SEM analysis reveals the presence of phosphospheres and P-rich morphotypes in the fly ash. Analysis of Güres and Campoaves ash samples has revealed that P is mainly present as hydroxyapatite crystals, CaCO3 relics, and CaO, as well as Na–K-Mg phosphate, unburnt char, and silica phases. The high P content of these ashes makes them promising for recovery purposes. The ESCAPE approach was validated and found to accurately evaluate the environmental impact of P recovery techniques, with wet sulfuric acid-based processes being the most appropriate and thermal-reduction dry processes being less sustainable.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
