ENVIRONMENTAL PERFORMANCE OF FOUR DIFFERENT METHODS FOR UTILIZATION OF THE PHOSPHORUS CONTENT IN SEWAGE SLUDGE FROM STOCKHOLM, SWEDEN
Magdalena Svanström1*, Morgan Fröling2, Kristin Johansson1, A. Maria Olsson1, and Agnes Mossakowska3
1Chemical Environmental Science, Chalmers University of Technology, Sweden
2Laboratory for Energy and the Environment, Massachusetts Institute of Technology, USA
3Environment and Development, Stockholm Water AB, Sweden
(free)
A study on the environmental performance of treatment options for the sewage sludge produced at Henriksdalsverket wastewater treatment plant in Stockholm, Sweden, was performed, using life cycle methodology. The plant generates 14,000 dry tons of digested sewage sludge annually. The four methods studied are: restoration of mining areas, composting with other biomaterials for use on golf courses, hygienisation through storage and use in agriculture, and supercritical water oxidation with phosphorus recovery according to the Aqua Reci method. The results are described as impacts on global warming, acidification, eutrophication, use of finite resources and primary energy. A very large impact of including biogeochemical emissions from sludge handling can be seen. System expansions for artificial fertilizers replaced by the systems also had a strong influence on the results. It is clear that it is important for the environmental outcome of sludge treatment options that biogeochemical emissions from sludge are minimized and that nutrients are efficiently utilized.
KEY WORDS Agriculture, composting, environmental assessment, LCA, life cycle assessment, restoration of mining area, SCWO, supercritical water oxidation
