Environmental Consequences of Pig Slurry Treatment Technologies: A Life Cycle Perspective
Research output: Book/Report › Ph.D. thesis
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Environmental Consequences of Pig Slurry Treatment Technologies : A Life Cycle Perspective. / ten Hoeve, Marieke.
Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 2015.Research output: Book/Report › Ph.D. thesis
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TY - BOOK
T1 - Environmental Consequences of Pig Slurry Treatment Technologies
T2 - A Life Cycle Perspective
AU - ten Hoeve, Marieke
PY - 2015
Y1 - 2015
N2 - Manure is a valuable fertiliser since it contains nutrients that are crucial for crop growth. Furthermore soilquality might be maintained or improved by the use of manure instead of mineral fertiliser, due to thepresence of organic matter in manure. On the other hand, emissions to the environment occur during manurestorage and after field application. The main emissions are ammonia, nitrous oxide, methane, carbon dioxide,nitrate, phosphorus and odour. Slurry treatment technologies have been and are being developed in order toreduce the environmental impacts of manure. However, it is important to analyse whether total impacts arereduced or merely result in burden shifting with impacts occurring in other life cycle stages or other impactcategories instead. Therefore, in the present thesis, life cycle assessment (LCA) was used in three separatestudies to analyse the environmental consequences of slurry acidification, separation and anaerobic digestion.The functional unit that formed the basis of the life cycle assessments in this thesis was the management of1000 kg of slurry excreted by fattening pigs under prevailing Danish conditions. A total of ten treatmentscenarios were compared with a reference scenario. The treatment scenarios were field acidification, in-houseacidification, screw press separation with and without composting of the solid fraction, decanter centrifugeseparation with and without ammonia stripping of the liquid fraction, and four anaerobic digestion scenarioswith different co-substrates. These co-substrates were straw that would otherwise have been left on the field,straw that would otherwise have been incinerated, the organic fraction of household waste and the solidfraction of slurry. The impact categories analysed were climate change potential including and excludingbiogenic carbon, marine and freshwater eutrophication potential, terrestrial acidification and eutrophicationpotential, and fossil resource depletion potential.The different types of treatment technologies showed varying environmental profiles, meaning that one typeof technology was beneficial for one impact category, but disadvantageous for another, while another typeshowed the opposite trends. Slurry acidification was the preferred technology for reducing terrestrialacidification and eutrophication potential, while slurry separation performed best for freshwatereutrophication, and anaerobic digestion showed the lowest impact potential for fossil resource depletion andmarine eutrophication. For climate change potential, whether a beneficial or disadvantageous impact potentialwas revealed depended on the specific technology (moment of acidification, separation and fraction upgradingtechnology, or co-substrate for anaerobic digestion). With respect to odorous emissions, an LCIA method wasdeveloped, but due to a lack of data it proved difficult to include odour in LCA. Regulations appear to have aninfluence on the environmental impacts of slurry treatment. A decrease in N application limits favours slurryacidification, but an increase in these limits is disadvantageous for acidification. This is due to the higher Ncontent in acidified slurry resulting in higher yields at limited N application rates. Furthermore, regulations area restricting factor for increasing pig production at single farm level.In conclusion, treatment had an influence on the environmental profile of pig slurry, but the choice of anappropriate slurry treatment technology depended on many considerations, e.g. local policy, cost andpracticality.
AB - Manure is a valuable fertiliser since it contains nutrients that are crucial for crop growth. Furthermore soilquality might be maintained or improved by the use of manure instead of mineral fertiliser, due to thepresence of organic matter in manure. On the other hand, emissions to the environment occur during manurestorage and after field application. The main emissions are ammonia, nitrous oxide, methane, carbon dioxide,nitrate, phosphorus and odour. Slurry treatment technologies have been and are being developed in order toreduce the environmental impacts of manure. However, it is important to analyse whether total impacts arereduced or merely result in burden shifting with impacts occurring in other life cycle stages or other impactcategories instead. Therefore, in the present thesis, life cycle assessment (LCA) was used in three separatestudies to analyse the environmental consequences of slurry acidification, separation and anaerobic digestion.The functional unit that formed the basis of the life cycle assessments in this thesis was the management of1000 kg of slurry excreted by fattening pigs under prevailing Danish conditions. A total of ten treatmentscenarios were compared with a reference scenario. The treatment scenarios were field acidification, in-houseacidification, screw press separation with and without composting of the solid fraction, decanter centrifugeseparation with and without ammonia stripping of the liquid fraction, and four anaerobic digestion scenarioswith different co-substrates. These co-substrates were straw that would otherwise have been left on the field,straw that would otherwise have been incinerated, the organic fraction of household waste and the solidfraction of slurry. The impact categories analysed were climate change potential including and excludingbiogenic carbon, marine and freshwater eutrophication potential, terrestrial acidification and eutrophicationpotential, and fossil resource depletion potential.The different types of treatment technologies showed varying environmental profiles, meaning that one typeof technology was beneficial for one impact category, but disadvantageous for another, while another typeshowed the opposite trends. Slurry acidification was the preferred technology for reducing terrestrialacidification and eutrophication potential, while slurry separation performed best for freshwatereutrophication, and anaerobic digestion showed the lowest impact potential for fossil resource depletion andmarine eutrophication. For climate change potential, whether a beneficial or disadvantageous impact potentialwas revealed depended on the specific technology (moment of acidification, separation and fraction upgradingtechnology, or co-substrate for anaerobic digestion). With respect to odorous emissions, an LCIA method wasdeveloped, but due to a lack of data it proved difficult to include odour in LCA. Regulations appear to have aninfluence on the environmental impacts of slurry treatment. A decrease in N application limits favours slurryacidification, but an increase in these limits is disadvantageous for acidification. This is due to the higher Ncontent in acidified slurry resulting in higher yields at limited N application rates. Furthermore, regulations area restricting factor for increasing pig production at single farm level.In conclusion, treatment had an influence on the environmental profile of pig slurry, but the choice of anappropriate slurry treatment technology depended on many considerations, e.g. local policy, cost andpracticality.
UR - https://soeg.kb.dk/permalink/45KBDK_KGL/fbp0ps/alma99122434289805763
M3 - Ph.D. thesis
BT - Environmental Consequences of Pig Slurry Treatment Technologies
PB - Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen
ER -
ID: 144795381