TP
T.J.F. Prot
info
Please Note
<p>This page displays the records of the person named above and is not linked to a unique person identifier. This record may need to be merged to a profile.</p>
1 records found
1
The global phosphorus challenge involves two interconnected issues: securing a sustainable phosphorus supply and reducing environmental pollution caused by phosphorus losses. Phosphorus is essential for all living organisms and is a critical component of mineral fertilizers. However, phosphate rock reserves are concentrated in a limited number of regions, including Morocco, Russia, United States, and China, creating supply vulnerabilities for import-dependent regions such as the European Union. At the same time, the largely linear use of phosphorus leads to accumulation in landfills, agricultural soils, and aquatic systems, where it drives eutrophication and ecosystem degradation. Recovering phosphorus from secondary streams such as manure, wastewater treatment sludge, and lake sediments offers a promising route to address both challenges.
This thesis focuses on phosphorus recovery through the formation of vivianite (Fe₃(PO₄)₂·8H₂O), a ferrous phosphate mineral with high thermodynamic stability and paramagnetic properties, enabling magnetic separation. Vivianite formation was investigated across manure, wastewater treatment sludge, and lake sediments to identify key barriers and opportunities for recovery.
The role of organic matter in vivianite formation was first examined. A phosphorus-to-dissolved-organic-carbon scale was introduced to evaluate how different organic compounds influence iron–phosphorus interactions. Organic ligands including bipyridine, citrate, humate, alginate, acetate, and dissolved organic matter from pig manure were tested for their effects on vivianite formation and dissolution. Citrate strongly inhibited vivianite formation and dissolved a substantial fraction of existing vivianite, while humate had a moderate inhibitory effect. In contrast, manure-derived dissolved organic matter had minimal influence on vivianite stability and primarily affected crystal morphology. These results showed that organic matter alone cannot explain reduced vivianite formation in pig manure.
The thesis then identified carbonate competition as a major limiting factor. In aged and digested manure, siderite (FeCO₃) formed preferentially over vivianite due to high dissolved inorganic carbon concentrations, causing carbonate to outcompete phosphate for ferrous iron. Reducing carbonate availability increased vivianite formation, both in fresh manure and in digested manure treated by gas stripping. Similar carbonate inhibition was observed in thermally hydrolyzed digested sludge, demonstrating that this limitation extends beyond manure.
Vivianite formation in dredged lake sediments was also investigated. Despite elevated phosphate concentrations typical of eutrophic systems, vivianite precipitation occurred only after additional phosphate dosing. This indicates that phosphate availability in sediments is limited and that competing anions such as carbonate and sulphide strongly influence iron binding. Analytical challenges further complicated vivianite quantification, highlighting the need for combined spectroscopic, microscopic, and extraction-based approaches. Overall, vivianite recovery from lake sediments appears limited.
Finally, the thesis examined the role of iron sulphides in limiting vivianite formation. Controlled oxidation of iron sulphides in digested sludge through microaeration was studied as a potential strategy to promote phosphorus recovery. Although sulphide destruction could not be conclusively demonstrated, reduced dissolved phosphate concentrations indicated enhanced iron–phosphate interactions. These findings suggest a practical pathway to improve phosphorus removal without increasing iron dosing.
Overall, this thesis shows that the dominant barriers to vivianite formation are carbonate competition in high-alkalinity systems such as manure and certain sludges, limited phosphate availability in sediments, and iron sulphide formation across all matrices. The carbonate barrier can be overcome, making vivianite recovery from pig manure technically feasible. More broadly, successful implementation of vivianite-based phosphorus recovery requires stronger integration across agricultural, environmental, and sanitation sectors. Addressing the global phosphorus challenge therefore demands not only technical innovation but also sustained transdisciplinary collaboration. ...
This thesis focuses on phosphorus recovery through the formation of vivianite (Fe₃(PO₄)₂·8H₂O), a ferrous phosphate mineral with high thermodynamic stability and paramagnetic properties, enabling magnetic separation. Vivianite formation was investigated across manure, wastewater treatment sludge, and lake sediments to identify key barriers and opportunities for recovery.
The role of organic matter in vivianite formation was first examined. A phosphorus-to-dissolved-organic-carbon scale was introduced to evaluate how different organic compounds influence iron–phosphorus interactions. Organic ligands including bipyridine, citrate, humate, alginate, acetate, and dissolved organic matter from pig manure were tested for their effects on vivianite formation and dissolution. Citrate strongly inhibited vivianite formation and dissolved a substantial fraction of existing vivianite, while humate had a moderate inhibitory effect. In contrast, manure-derived dissolved organic matter had minimal influence on vivianite stability and primarily affected crystal morphology. These results showed that organic matter alone cannot explain reduced vivianite formation in pig manure.
The thesis then identified carbonate competition as a major limiting factor. In aged and digested manure, siderite (FeCO₃) formed preferentially over vivianite due to high dissolved inorganic carbon concentrations, causing carbonate to outcompete phosphate for ferrous iron. Reducing carbonate availability increased vivianite formation, both in fresh manure and in digested manure treated by gas stripping. Similar carbonate inhibition was observed in thermally hydrolyzed digested sludge, demonstrating that this limitation extends beyond manure.
Vivianite formation in dredged lake sediments was also investigated. Despite elevated phosphate concentrations typical of eutrophic systems, vivianite precipitation occurred only after additional phosphate dosing. This indicates that phosphate availability in sediments is limited and that competing anions such as carbonate and sulphide strongly influence iron binding. Analytical challenges further complicated vivianite quantification, highlighting the need for combined spectroscopic, microscopic, and extraction-based approaches. Overall, vivianite recovery from lake sediments appears limited.
Finally, the thesis examined the role of iron sulphides in limiting vivianite formation. Controlled oxidation of iron sulphides in digested sludge through microaeration was studied as a potential strategy to promote phosphorus recovery. Although sulphide destruction could not be conclusively demonstrated, reduced dissolved phosphate concentrations indicated enhanced iron–phosphate interactions. These findings suggest a practical pathway to improve phosphorus removal without increasing iron dosing.
Overall, this thesis shows that the dominant barriers to vivianite formation are carbonate competition in high-alkalinity systems such as manure and certain sludges, limited phosphate availability in sediments, and iron sulphide formation across all matrices. The carbonate barrier can be overcome, making vivianite recovery from pig manure technically feasible. More broadly, successful implementation of vivianite-based phosphorus recovery requires stronger integration across agricultural, environmental, and sanitation sectors. Addressing the global phosphorus challenge therefore demands not only technical innovation but also sustained transdisciplinary collaboration. ...
The global phosphorus challenge involves two interconnected issues: securing a sustainable phosphorus supply and reducing environmental pollution caused by phosphorus losses. Phosphorus is essential for all living organisms and is a critical component of mineral fertilizers. However, phosphate rock reserves are concentrated in a limited number of regions, including Morocco, Russia, United States, and China, creating supply vulnerabilities for import-dependent regions such as the European Union. At the same time, the largely linear use of phosphorus leads to accumulation in landfills, agricultural soils, and aquatic systems, where it drives eutrophication and ecosystem degradation. Recovering phosphorus from secondary streams such as manure, wastewater treatment sludge, and lake sediments offers a promising route to address both challenges.
This thesis focuses on phosphorus recovery through the formation of vivianite (Fe₃(PO₄)₂·8H₂O), a ferrous phosphate mineral with high thermodynamic stability and paramagnetic properties, enabling magnetic separation. Vivianite formation was investigated across manure, wastewater treatment sludge, and lake sediments to identify key barriers and opportunities for recovery.
The role of organic matter in vivianite formation was first examined. A phosphorus-to-dissolved-organic-carbon scale was introduced to evaluate how different organic compounds influence iron–phosphorus interactions. Organic ligands including bipyridine, citrate, humate, alginate, acetate, and dissolved organic matter from pig manure were tested for their effects on vivianite formation and dissolution. Citrate strongly inhibited vivianite formation and dissolved a substantial fraction of existing vivianite, while humate had a moderate inhibitory effect. In contrast, manure-derived dissolved organic matter had minimal influence on vivianite stability and primarily affected crystal morphology. These results showed that organic matter alone cannot explain reduced vivianite formation in pig manure.
The thesis then identified carbonate competition as a major limiting factor. In aged and digested manure, siderite (FeCO₃) formed preferentially over vivianite due to high dissolved inorganic carbon concentrations, causing carbonate to outcompete phosphate for ferrous iron. Reducing carbonate availability increased vivianite formation, both in fresh manure and in digested manure treated by gas stripping. Similar carbonate inhibition was observed in thermally hydrolyzed digested sludge, demonstrating that this limitation extends beyond manure.
Vivianite formation in dredged lake sediments was also investigated. Despite elevated phosphate concentrations typical of eutrophic systems, vivianite precipitation occurred only after additional phosphate dosing. This indicates that phosphate availability in sediments is limited and that competing anions such as carbonate and sulphide strongly influence iron binding. Analytical challenges further complicated vivianite quantification, highlighting the need for combined spectroscopic, microscopic, and extraction-based approaches. Overall, vivianite recovery from lake sediments appears limited.
Finally, the thesis examined the role of iron sulphides in limiting vivianite formation. Controlled oxidation of iron sulphides in digested sludge through microaeration was studied as a potential strategy to promote phosphorus recovery. Although sulphide destruction could not be conclusively demonstrated, reduced dissolved phosphate concentrations indicated enhanced iron–phosphate interactions. These findings suggest a practical pathway to improve phosphorus removal without increasing iron dosing.
Overall, this thesis shows that the dominant barriers to vivianite formation are carbonate competition in high-alkalinity systems such as manure and certain sludges, limited phosphate availability in sediments, and iron sulphide formation across all matrices. The carbonate barrier can be overcome, making vivianite recovery from pig manure technically feasible. More broadly, successful implementation of vivianite-based phosphorus recovery requires stronger integration across agricultural, environmental, and sanitation sectors. Addressing the global phosphorus challenge therefore demands not only technical innovation but also sustained transdisciplinary collaboration.
This thesis focuses on phosphorus recovery through the formation of vivianite (Fe₃(PO₄)₂·8H₂O), a ferrous phosphate mineral with high thermodynamic stability and paramagnetic properties, enabling magnetic separation. Vivianite formation was investigated across manure, wastewater treatment sludge, and lake sediments to identify key barriers and opportunities for recovery.
The role of organic matter in vivianite formation was first examined. A phosphorus-to-dissolved-organic-carbon scale was introduced to evaluate how different organic compounds influence iron–phosphorus interactions. Organic ligands including bipyridine, citrate, humate, alginate, acetate, and dissolved organic matter from pig manure were tested for their effects on vivianite formation and dissolution. Citrate strongly inhibited vivianite formation and dissolved a substantial fraction of existing vivianite, while humate had a moderate inhibitory effect. In contrast, manure-derived dissolved organic matter had minimal influence on vivianite stability and primarily affected crystal morphology. These results showed that organic matter alone cannot explain reduced vivianite formation in pig manure.
The thesis then identified carbonate competition as a major limiting factor. In aged and digested manure, siderite (FeCO₃) formed preferentially over vivianite due to high dissolved inorganic carbon concentrations, causing carbonate to outcompete phosphate for ferrous iron. Reducing carbonate availability increased vivianite formation, both in fresh manure and in digested manure treated by gas stripping. Similar carbonate inhibition was observed in thermally hydrolyzed digested sludge, demonstrating that this limitation extends beyond manure.
Vivianite formation in dredged lake sediments was also investigated. Despite elevated phosphate concentrations typical of eutrophic systems, vivianite precipitation occurred only after additional phosphate dosing. This indicates that phosphate availability in sediments is limited and that competing anions such as carbonate and sulphide strongly influence iron binding. Analytical challenges further complicated vivianite quantification, highlighting the need for combined spectroscopic, microscopic, and extraction-based approaches. Overall, vivianite recovery from lake sediments appears limited.
Finally, the thesis examined the role of iron sulphides in limiting vivianite formation. Controlled oxidation of iron sulphides in digested sludge through microaeration was studied as a potential strategy to promote phosphorus recovery. Although sulphide destruction could not be conclusively demonstrated, reduced dissolved phosphate concentrations indicated enhanced iron–phosphate interactions. These findings suggest a practical pathway to improve phosphorus removal without increasing iron dosing.
Overall, this thesis shows that the dominant barriers to vivianite formation are carbonate competition in high-alkalinity systems such as manure and certain sludges, limited phosphate availability in sediments, and iron sulphide formation across all matrices. The carbonate barrier can be overcome, making vivianite recovery from pig manure technically feasible. More broadly, successful implementation of vivianite-based phosphorus recovery requires stronger integration across agricultural, environmental, and sanitation sectors. Addressing the global phosphorus challenge therefore demands not only technical innovation but also sustained transdisciplinary collaboration.