Small flexible sanitation solutions: adaptation to a changing world (2016-2019)

In this project we investigate decentralised sanitation systems with regard to their sustainability and resilience and in comparison to centralised sanitation solutions. The project is funded by the Swedish Research Council Formas.

Current centralised sanitation in developed countries using end-of-pipe technology is inflexible due to large investment costs for treatment plants and pipe networks.

Decentralisation and source separation have been identified as a major area of sustainable sanitation. Flexible decentralised solutions are needed when (parts of) the current sanitation systems need to change, e.g. due to urbanisation, de-population or ageing infrastructure.

System changes can also consist in the reuse of treated wastewater and the introduction of more sustainable solutions such as water-saving appliances, or source-separating systems in one part of a city. Although the flexibility of decentralised systems can have practical value in many places, the current strategy pursued by Swedish municipalities is often centralisation. Source-separating systems are rarely applied despite their potential for nutrient recovery. In this project, we evaluate sanitation systems of small communities (5 to 2000 pe) with regard to their sustainability and resilience from both an engineering and historical/societal perspective. We compare various common system technologies with each other and with decentralised and/or source separating solutions using i.a. multi-criteria analysis. We also investigate what causes system inertia and what can facilitate the adoption of more sustainable solutions by qualitatively analysing sector journals and water policies and interviews in municipalities.

The project is funded by Formas. It is a collaboration of Urban Water Engineering and History of Technology at LTU, as well as Hallvard Ødegaard, Professor emeritus at NTNU, Norway.

Inga Herrmann, Annelie Hedström, Brenda Vidal, Kristina Söderholm and Maria Viklander