title: Sewage sludge as fertiliser - environmental assessment of storage and land application options.
abstract: Sewage sludge (SS) contains beneficial plant nutrients and organic matter, and therefore application of SS on agricultural land helps close nutrient loops. However, spreading operations are restricted to certain seasons and hence the SS needs to be stored. Storage and land application of SS are both potential sources of greenhouse gases and ammonia, leading to global warming, acidification and eutrophication. Covering the stored SS, treating it with urea and choosing the correct time for land application all have the potential to reduce emissions from the system. Using life cycle assessment (LCA), this study compares storage and land application options of SS in terms of global warming potential (GWP), acidification potential, eutrophication potential and primary energy use. The system with covered storage has the lowest impact of all categories. Systems with autumn application are preferable to spring application for all impact categories but, when nitrate leaching is considered, spring application is preferable in terms of eutrophication and primary energy use and, for some SS treatments, GWP. Ammonia addition reduces nitrous oxide and ammonia emissions during storage, but increases these emissions after land application. Storage duration has a large impact on GWP, while amount of chemical nitrogen fertiliser substituted has a large impact on primary energy use.
authors.affiliation: Department of Energy and Technology, Swedish University of Agricultural Sciences, Box 7032, SE-750 07 Uppsala, Sweden E-mail: agnes.willen@slu.se; Swedish Institute of Agricultural and Environmental Engineering, Box 7033, SE-750 07 Uppsala, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Willén
authors.affiliation: Swedish Environmental Research Institute, Box 210 60, SE-100 31 Stockholm, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Junestedt
authors.affiliation: Swedish Institute of Agricultural and Environmental Engineering, Box 7033, SE-750 07 Uppsala, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Rodhe
authors.affiliation: Department of Microbiology, Swedish University of Agricultural Sciences, Box 7025, SE-750 07 Uppsala, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Pell
authors.affiliation: Department of Energy and Technology, Swedish University of Agricultural Sciences, Box 7032, SE-750 07 Uppsala, Sweden E-mail: agnes.willen@slu.se.
authors.forename: H
authors.initials: H
authors.lastname: Jönsson
mesh_terms: D000143:Acids / Q000737:chemistry; D000393:Air Pollutants / Q000032:analysis; D000641:Ammonia / Q000032:analysis; D057965:Carbon Sequestration; D004777:Environment; D005068:Eutrophication; D005308:Fertilizers / Q000032:analysis*; D057232:Global Warming; D008697:Methane / Q000032:analysis; D009566:Nitrates / Q000032:analysis; D009584:Nitrogen / Q000032:analysis; D009609:Nitrous Oxide / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D012621:Seasons; D012722:Sewage; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D000143:Acids; D000393:Air Pollutants; D005308:Fertilizers; D009566:Nitrates; D012722:Sewage; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D000641:Ammonia; D009609:Nitrous Oxide; D009584:Nitrogen; D008697:Methane