Sustainable phosphorus removal in onsite wastewater treatment
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Aquatic eutrophication is a serious environmental problem that occurs all over the world. To protect surface waters (in particular the Baltic Sea), the regulatory pressure on onsite wastewater treatment (OWT) systems have increased in Sweden. Stringent requirements have led to uncertainties regarding the capability of conventional treatment techniques (soil treatment systems (STS)) to remove phosphorus (P), but they have also stimulated the development and introduction of enhanced P treatment techniques. In this thesis the accumulation and mobility of P as well as the chemical P removal mechanisms were studied in soils and reactive filter media. This knowledge was then used in environmental systems analysis. A model based on life cycle assessment (LCA) methodology was developed to evaluate the overall environmental performance of conventional and enhanced P treatment systems under various local conditions. The P accumulation in the studied STS varied (320-870 g m-3) and the accumulated P was rather mobile in some soils. Phosphorus compounds were identified in alkaline reactive filter media (calcium phosphates predominated) by means of X-ray Absorption Near Edge Structure (XANES). In sandy soils from STS aluminium was found to be a key element for P removal, as evidenced by a strong relationship between oxalate-extractable P and Al. The LCA studies indicated that enhanced P treatment systems may be beneficial from an eutrophication and P recycling perspective but causes increased impacts in terms of global warming and acidification. Despite the drawbacks, enhanced P treatment techniques should be considered suitable substitutes to surface water discharge STS under most conditions. This is because the latter systems have such a strong eutrophication impact. On the other hand, under appropriate conditions, STS with groundwater discharge may be advantageous. These systems generally caused low environmental impacts except for the dispersion of P resources.
Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. , xii, 34 p.
Trita-LWR. PHD, ISSN 1650-8602 ; 1070
Onsite wastewater treatment, Soil treatment system, Phosphorus, Removal mechanisms, Environmental impacts, Life cycle assessment
Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:kth:diva-121049ISBN: 978-91-7501-730-3OAI: oai:DiVA.org:kth-121049DiVA: diva2:616601
2013-05-13, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Withers, Paul, Professor
Gustafsson, Jon Petter, ProfessorRenman, Gunno, ProfessorKärrman, Erik, PhD
QC 201304192013-04-192013-04-172013-04-19Bibliographically approved
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