Fates of nutrient elements and heavy metals during thermal conversion of cattle slurry-derived anaerobic digestates
Abstract Thermal processes are emerging as promising solutions to recovering phosphorus and other nutrient elements from anaerobic digestates. The feasibility of nutrient element recovery depends largely on the fates of nutrient elements and heavy metals during thermal processing. This study assesse...
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SpringerOpen
2024-12-01
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| Series: | Bioresources and Bioprocessing |
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| Online Access: | https://doi.org/10.1186/s40643-024-00828-7 |
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| author | Daniel J. Lane Olli Sippula Jorma Jokiniemi Mikko Heimonen Niko M. Kinnunen Perttu Virkajärvi Narasinha Shurpali |
| author_facet | Daniel J. Lane Olli Sippula Jorma Jokiniemi Mikko Heimonen Niko M. Kinnunen Perttu Virkajärvi Narasinha Shurpali |
| author_sort | Daniel J. Lane |
| collection | DOAJ |
| description | Abstract Thermal processes are emerging as promising solutions to recovering phosphorus and other nutrient elements from anaerobic digestates. The feasibility of nutrient element recovery depends largely on the fates of nutrient elements and heavy metals during thermal processing. This study assesses the partitioning of macronutrients (N, P, K, Na, Ca and Mg) and heavy metals (Zn, Cu, and Mn) between condensed and gaseous phases during thermal conversion of cattle slurry digestates in gas atmospheres of pyrolysis, combustion, and gasification processes. This study also assesses the chemical forms of macronutrients retained in combustion ashes. The partitioning of elements between condensed and gaseous phases was quantified by mass balances based on elemental analyses of char and ash residues. The char and ash residues were prepared in a fixed-bed, batch reactor at temperatures within the range 800–1000 °C. Powder X-ray diffraction was used to identify the chemical forms of macronutrient elements in combustion ashes. Volatilisation of P was low (< 20%) when the digestates were heated in inert and oxidising atmospheres, whereas a reducing atmosphere volatilized P to a major extent (~ 60% at 1000 °C). Oxidising atmospheres increased volatilisation of N but suppressed volatilisation of K, Na, and Zn. Volatilisation of the following elements was low (< 30%) in all investigated operating conditions: Ca, Mg, Mn, and Cu. The combustion ashes contained both high concentrations of P (around 7 w/w%) and acceptable concentrations of regulated heavy metals (Cu, and Zn) for application on agricultural and forest soils in Finland. Phosphorous was retained in the combustion ashes in the form of whitlockite. This form of P is expected to be available to plants when the ashes are added to soil. |
| format | Article |
| id | doaj-art-09a7eadb10e3456a9e08f8c298736fdf |
| institution | Kabale University |
| issn | 2197-4365 |
| language | English |
| publishDate | 2024-12-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Bioresources and Bioprocessing |
| spelling | doaj-art-09a7eadb10e3456a9e08f8c298736fdf2025-01-05T12:07:12ZengSpringerOpenBioresources and Bioprocessing2197-43652024-12-0111111310.1186/s40643-024-00828-7Fates of nutrient elements and heavy metals during thermal conversion of cattle slurry-derived anaerobic digestatesDaniel J. Lane0Olli Sippula1Jorma Jokiniemi2Mikko Heimonen3Niko M. Kinnunen4Perttu Virkajärvi5Narasinha Shurpali6Commonwealth Scientific and Industrial Research Organization (CSIRO), Queensland Centre for Advanced Technologies (QCAT)Department of Chemistry, University of Eastern FinlandDepartment of Environmental and Biological Sciences, University of Eastern FinlandDepartment of Environmental and Biological Sciences, University of Eastern FinlandDepartment of Chemistry, University of Eastern FinlandProduction Systems Unit, Grasslands and Sustainable Agriculture Group, Natural Resources Institute Finland (Luke)Production Systems Unit, Grasslands and Sustainable Agriculture Group, Natural Resources Institute Finland (Luke)Abstract Thermal processes are emerging as promising solutions to recovering phosphorus and other nutrient elements from anaerobic digestates. The feasibility of nutrient element recovery depends largely on the fates of nutrient elements and heavy metals during thermal processing. This study assesses the partitioning of macronutrients (N, P, K, Na, Ca and Mg) and heavy metals (Zn, Cu, and Mn) between condensed and gaseous phases during thermal conversion of cattle slurry digestates in gas atmospheres of pyrolysis, combustion, and gasification processes. This study also assesses the chemical forms of macronutrients retained in combustion ashes. The partitioning of elements between condensed and gaseous phases was quantified by mass balances based on elemental analyses of char and ash residues. The char and ash residues were prepared in a fixed-bed, batch reactor at temperatures within the range 800–1000 °C. Powder X-ray diffraction was used to identify the chemical forms of macronutrient elements in combustion ashes. Volatilisation of P was low (< 20%) when the digestates were heated in inert and oxidising atmospheres, whereas a reducing atmosphere volatilized P to a major extent (~ 60% at 1000 °C). Oxidising atmospheres increased volatilisation of N but suppressed volatilisation of K, Na, and Zn. Volatilisation of the following elements was low (< 30%) in all investigated operating conditions: Ca, Mg, Mn, and Cu. The combustion ashes contained both high concentrations of P (around 7 w/w%) and acceptable concentrations of regulated heavy metals (Cu, and Zn) for application on agricultural and forest soils in Finland. Phosphorous was retained in the combustion ashes in the form of whitlockite. This form of P is expected to be available to plants when the ashes are added to soil.https://doi.org/10.1186/s40643-024-00828-7Ash utilizationCombustionGasificationPyrolysisPhosphorous recoveryVolatilization |
| spellingShingle | Daniel J. Lane Olli Sippula Jorma Jokiniemi Mikko Heimonen Niko M. Kinnunen Perttu Virkajärvi Narasinha Shurpali Fates of nutrient elements and heavy metals during thermal conversion of cattle slurry-derived anaerobic digestates Bioresources and Bioprocessing Ash utilization Combustion Gasification Pyrolysis Phosphorous recovery Volatilization |
| title | Fates of nutrient elements and heavy metals during thermal conversion of cattle slurry-derived anaerobic digestates |
| title_full | Fates of nutrient elements and heavy metals during thermal conversion of cattle slurry-derived anaerobic digestates |
| title_fullStr | Fates of nutrient elements and heavy metals during thermal conversion of cattle slurry-derived anaerobic digestates |
| title_full_unstemmed | Fates of nutrient elements and heavy metals during thermal conversion of cattle slurry-derived anaerobic digestates |
| title_short | Fates of nutrient elements and heavy metals during thermal conversion of cattle slurry-derived anaerobic digestates |
| title_sort | fates of nutrient elements and heavy metals during thermal conversion of cattle slurry derived anaerobic digestates |
| topic | Ash utilization Combustion Gasification Pyrolysis Phosphorous recovery Volatilization |
| url | https://doi.org/10.1186/s40643-024-00828-7 |
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