Sewage sludge is a surplus product in waste water treatment plants through the removal of the wastewater ingredients. The ingredients in addition to the so-called recyclable materials (e.g. phosphorus) are also potential pollutants of anthropogenic origin. Due to legal obligations for wastewater treatment sludge is permanently produced. Therefore, a secured disposal must be assured. This present study deals with the amounts of sewage sludge and the types of sludge disposal through the ages. Current and future procedures will be presented and the legal bases will be dwelt on. Furthermore, methods for the ecological and economic assessment of disposal methods are presented. The practical part deals with the application of ecological, economic and social evaluation processes of selected disposal routes by multi criteria analysis (MCA). The selected paths are made up of current methods co-incineration, mono-incineration and agricultural use - and of a technically innovative method - hydrothermal carbonisation (HTC). By looking at the overall results of the MCA it is evident that mono-incineration and co-incineration are significantly better than the agricultural use and the HTC. In the environmental assessment thermal processes perform significantly better than the agricultural use because through ash landfilling pollutants are removed from the system and thus only a minor amount gets into contact with the environment. A different picture emerges in the economic analysis. Due to the low investment and disposal costs, the agricultural use shows the best performance by far. The result of social evaluation is mainly influenced by the dry matter content and the ability to recover phosphorus.