Developing a model based decision support tool for the identification of sustainable treatment options for domestic wastewater

To enable decision makers to select sustainable wastewater treatment system s, insight into the sustainability of a wide variety of systems should be p rovided in a transparent way leaving room for adaptation and interpretation according to the local situation. To provide this insight a structured met hodology comparing wastewater treatment systems with respect to sustainabil ity is defined. Similar to life cycle assessment (LCA) three phases can be distinguished: (I)goal and scope definition, (2) inventory analysis, and (3 ) optimisation and results. In the goal and scope definition we set the sys tem boundaries to include most of the water cycle and part of the food cycl e. Furthermore, we defined a multi-disciplinary set of sustainability indic ators including technical. economic, environmental, and socio-cultural aspe cts. In the inventory analysis these sustainability indicators are quantifi ed using simple static models of wastewater unit operations. Selection of u nit operations results in a model of a complete wastewater treatment system . In the optimisation phase the decision maker can weigh the different sust ainability indicators and select sustainable options through integer progra mming.