The use of thermal energy from various parts of the wastewater infrastructure has received increased attention in recent years. The energy potential and the risk for the undisturbed operation of wastewater discharge and treatment must be assessed in order to make a prediction regarding the benefits and risks of obtaining thermal energy from wastewater networks. The result supports the operator / decision maker as basis for an implementation decision and/or approval.
Within the framework of this project, a potential and risk map for the Graz wastewater network was developed based on temperature modeling of the combined sewer system and a following risk assessment. For this, a detailed, physically based temperature model was implemented in EPA's SWMM5, a detailed sewer network model of the city of Graz was created and based on Monte-Carlo simulations potential implementations regarding place and installed capacity analyzed. For calibration, comprehensive long-term measurement campaigns for wastewater temperature, sewer air temperature and ground temperature were conducted.