Environmental systems analysis on enhanced phosphorus removal in onsite wastewater treatment
(English)Manuscript (preprint) (Other academic)
In order to minimize phosphorus (P) loads to surface waters, the regulatory pressure on onsite wastewater treatment systems has increased. However, the environmental side-effects of implementing secondary P treatment have not been seriously reviewed. In this study we hypothesized that local conditions will largely govern the overall environmental benefits and drawbacks of different options for onsite wastewater treatment from a regional perspective. To explore the validity of this hypothesis an environmental systems analysis (ESA) model was developed that could handle differences in local conditions. The model was applied for four different treatment options, two conventional and two enhanced P treatment options. In a sensitivity analysis three diverse local contexts (type cases) were configured to evaluate the overall environmental impacts from the local and the regional perspective. The evaluation indicated that the eutrophication impacts from onsite wastewater treatment systems are significant in relation to the mean per capita contributions. This statement was valid even at a regional perspective as long as the natural retention was not very strong. Thus, the environmental side effects (increased emissions of greenhouse gases (GHG) and acidifying substances) of implementation of enhanced treatment solutions might be justifiable in many situations. However, due to a low impact in most of the studied environmental aspects, groundwater discharging soil treatment systems (STS) seemed to be preferable in areas were hydrogeological conditions are satisfactory and the distance to surface water is sufficient.
Onsite wastewater treatment, Soil treatment system, Reactive filter, Eutrophication, Environmental impact, Environmental Systems Analysis, Life cycle assessment
IdentifiersURN: urn:nbn:se:kth:diva-121048OAI: oai:DiVA.org:kth-121048DiVA: diva2:616563
QS 20132013-04-172013-04-172013-04-19Bibliographically approved