Emergy and Socio-Ecological Principles in Sustainability Assessment: Methodological Considerations from a Wastewater Treatment Case Study

This paper focuses on the methodological aspects for emergy analysis (EA) and socioecological principles (SEP) methods that were previously used for sustainability assessment in a wastewater treatment case study (Grönlund et al. 2004). Grönlund et al. (2004) constructed a model of a microalgae wastewater treatment plant (ALGA), located in Sweden at latitude 60°N, and tested it by comparing it to both a conventional three-step treatment plant and a mechanical and chemical treatment plant complemented with a constructed wetland. Based on a chosen framework (the R framework) defining sustainability and sustainable development and the results from the two assessment methods, the ALGA model was considered to have a better position for sustainable development than the other two. In this paper the performance of the methods are compared, including a discussion on how they relate to the concept of sustainability, which reveals different underlying views on the concept of sustainability and uncertainties in the methodological procedures. The SEP method fits well into the chosen framework of sustainability, while the EA method is more open to other definitions of sustainability. Regardless of some fundamental differences between the methods, the ranking of different options were identical in the case study. This result may appear reassuring, but the methodological discussion clearly suggests that more studies are needed on the operationalization of sustainable development and the related tools for its assessment.